Dramatically improves C++ demangling performance by introducing a new implementation...
authorKate Stone <katherine.stone@apple.com>
Tue, 22 Jul 2014 17:03:38 +0000 (17:03 +0000)
committerKate Stone <katherine.stone@apple.com>
Tue, 22 Jul 2014 17:03:38 +0000 (17:03 +0000)
The new implementation is located in source/Core/FastDemangle.cpp.  It’s fairly straightforward C code with a few basic C++ extensions.  It should compile with little or no change on a variety of platforms, but of course it is still only useful for symbols that comply with the Itanium ABI mangling spec (plus a few Clang extensions.)

<rdar://problem/15397553> <rdar://problem/15794867>

llvm-svn: 213671

lldb/lldb.xcodeproj/project.pbxproj
lldb/source/Core/CMakeLists.txt
lldb/source/Core/FastDemangle.cpp [new file with mode: 0644]
lldb/source/Core/Mangled.cpp

index 2e2a16e..d721a5f 100644 (file)
                26FFC19C14FC072100087D58 /* DYLDRendezvous.h in Headers */ = {isa = PBXBuildFile; fileRef = 26FFC19614FC072100087D58 /* DYLDRendezvous.h */; };
                26FFC19D14FC072100087D58 /* DynamicLoaderPOSIXDYLD.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 26FFC19714FC072100087D58 /* DynamicLoaderPOSIXDYLD.cpp */; };
                26FFC19E14FC072100087D58 /* DynamicLoaderPOSIXDYLD.h in Headers */ = {isa = PBXBuildFile; fileRef = 26FFC19814FC072100087D58 /* DynamicLoaderPOSIXDYLD.h */; };
+               449ACC98197DEA0B008D175E /* FastDemangle.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 449ACC96197DE9EC008D175E /* FastDemangle.cpp */; };
                490A36C0180F0E6F00BA31F8 /* PlatformWindows.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 490A36BD180F0E6F00BA31F8 /* PlatformWindows.cpp */; };
                490A36C2180F0E9300BA31F8 /* PlatformWindows.h in Headers */ = {isa = PBXBuildFile; fileRef = 490A36BE180F0E6F00BA31F8 /* PlatformWindows.h */; };
                490A966B1628C3BF00F0002E /* SBDeclaration.h in Headers */ = {isa = PBXBuildFile; fileRef = 9452573816262CEF00325455 /* SBDeclaration.h */; settings = {ATTRIBUTES = (Public, ); }; };
                26FFC19614FC072100087D58 /* DYLDRendezvous.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DYLDRendezvous.h; sourceTree = "<group>"; };
                26FFC19714FC072100087D58 /* DynamicLoaderPOSIXDYLD.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = DynamicLoaderPOSIXDYLD.cpp; sourceTree = "<group>"; };
                26FFC19814FC072100087D58 /* DynamicLoaderPOSIXDYLD.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DynamicLoaderPOSIXDYLD.h; sourceTree = "<group>"; };
+               449ACC96197DE9EC008D175E /* FastDemangle.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = FastDemangle.cpp; path = source/Core/FastDemangle.cpp; sourceTree = "<group>"; };
                4906FD4012F2255300A2A77C /* ASTDumper.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = ASTDumper.cpp; path = source/Expression/ASTDumper.cpp; sourceTree = "<group>"; };
                4906FD4412F2257600A2A77C /* ASTDumper.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = ASTDumper.h; path = include/lldb/Expression/ASTDumper.h; sourceTree = "<group>"; };
                490A36BD180F0E6F00BA31F8 /* PlatformWindows.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = PlatformWindows.cpp; sourceTree = "<group>"; };
                                26BC7E7810F1B85900F91463 /* Error.cpp */,
                                26BC7D6110F1B77400F91463 /* Event.h */,
                                26BC7E7910F1B85900F91463 /* Event.cpp */,
+                               449ACC96197DE9EC008D175E /* FastDemangle.cpp */,
                                26BD407D135D2AC400237D80 /* FileLineResolver.h */,
                                26BD407E135D2ADF00237D80 /* FileLineResolver.cpp */,
                                26BC7D6310F1B77400F91463 /* FileSpecList.h */,
                                2689000113353DB600698AC0 /* BreakpointResolverAddress.cpp in Sources */,
                                2689000313353DB600698AC0 /* BreakpointResolverFileLine.cpp in Sources */,
                                26474CA818D0CB070073DEBA /* RegisterContextFreeBSD_i386.cpp in Sources */,
+                               449ACC98197DEA0B008D175E /* FastDemangle.cpp in Sources */,
                                94CD705216F8F5BC00CF1E42 /* LibCxxMap.cpp in Sources */,
                                2689000513353DB600698AC0 /* BreakpointResolverName.cpp in Sources */,
                                2689000713353DB600698AC0 /* BreakpointSite.cpp in Sources */,
index 709433f..6cd5418 100644 (file)
@@ -25,6 +25,7 @@ add_lldb_library(lldbCore
   EmulateInstruction.cpp
   Error.cpp
   Event.cpp
+  FastDemangle.cpp
   FileLineResolver.cpp
   FileSpecList.cpp
   History.cpp
diff --git a/lldb/source/Core/FastDemangle.cpp b/lldb/source/Core/FastDemangle.cpp
new file mode 100644 (file)
index 0000000..00a7542
--- /dev/null
@@ -0,0 +1,2203 @@
+//===-- FastDemangle.cpp ----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+//#define DEBUG_FAILURES 1
+//#define DEBUG_SUBSTITUTIONS 1
+//#define DEBUG_TEMPLATE_ARGS 1
+//#define DEBUG_HIGHWATER 1
+//#define DEBUG_REORDERING 1
+
+namespace {
+    
+/// @brief Represents the collection of qualifiers on a type
+
+enum Qualifiers
+{
+    QualifierNone = 0,
+    QualifierConst = 1,
+    QualifierRestrict = 2,
+    QualifierVolatile = 4,
+    QualifierReference = 8,
+    QualifierRValueReference = 16,
+    QualifierPointer = 32
+};
+
+/// @brief Categorizes the recognized operators
+
+enum class OperatorKind
+{
+    Unary,
+    Postfix,
+    Binary,
+    Ternary,
+    Other,
+    ConversionOperator,
+    Vendor,
+    NoMatch
+};
+
+/// @brief Represents one of the recognized two-character operator
+/// abbreviations used when parsing operators as names and expressions
+
+struct Operator
+{
+    const char * name;
+    OperatorKind kind;
+};
+
+/// @brief Represents a range of characters in the output buffer, typically for
+/// use with RewriteRange()
+
+struct BufferRange
+{
+    int offset;
+    int length;
+};
+
+/// @brief Transient state required while parsing a name
+
+struct NameState
+{
+    bool parse_function_params;
+    bool is_last_generic;
+    bool has_no_return_type;
+    BufferRange last_name_range;
+};
+
+/// @brief LLDB's fast C++ demangler
+///
+/// This is an incomplete implementation designed to speed up the demangling
+/// process that is often a bottleneck when LLDB stops a process for the first
+/// time.  Where the implementation doesn't know how to demangle a symbol it
+/// fails gracefully to allow the caller to fall back to the existing demangler.
+///
+/// Over time the full mangling spec should be supported without compromising
+/// performance for the most common cases.
+
+class SymbolDemangler
+{
+public:
+    
+    //----------------------------------------------------
+    // Public API
+    //----------------------------------------------------
+    
+    /// @brief Create a SymbolDemangler
+    ///
+    /// The newly created demangler allocates and owns scratch memory sufficient
+    /// for demangling typical symbols.  Additional memory will be allocated if
+    /// needed and managed by the demangler instance.
+    
+    SymbolDemangler()
+    {
+        buffer = (char *) malloc(8192);
+        buffer_end = buffer + 8192;
+        owns_buffer = true;
+        
+        rewrite_ranges = (BufferRange *) malloc(128 * sizeof(BufferRange));
+        rewrite_ranges_size = 128;
+        owns_rewrite_ranges = true;
+    }
+    
+    /// @brief Create a SymbolDemangler that uses provided scratch memory
+    ///
+    /// The provided memory is not owned by the demangler.  It will be
+    /// overwritten during calls to GetDemangledCopy() but can be used for
+    /// other purposes between calls.  The provided memory will not be freed
+    /// when this instance is destroyed.
+    ///
+    /// If demangling a symbol requires additional space it will be allocated
+    /// and managed by the demangler instance.
+    ///
+    /// @param storage_ptr Valid pointer to at least storage_size bytes of
+    /// space that the SymbolDemangler can use during demangling
+    ///
+    /// @param storage_size Number of bytes of space available scratch memory
+    /// referenced by storage_ptr
+    
+    SymbolDemangler(void * storage_ptr, int storage_size)
+    {
+        // Use up to 1/8th of the provided space for rewrite ranges
+        rewrite_ranges_size = (storage_size >> 3) / sizeof(BufferRange);
+        rewrite_ranges = (BufferRange *) storage_ptr;
+        owns_rewrite_ranges = false;
+        
+        // Use the rest for the character buffer
+        buffer = (char *) storage_ptr + rewrite_ranges_size * sizeof(BufferRange);
+        buffer_end = (const char *)storage_ptr + storage_size;
+        owns_buffer = false;
+    }
+    
+    /// @brief Destroys the SymbolDemangler and deallocates any scratch
+    /// memory that it owns
+    
+    ~SymbolDemangler()
+    {
+        if (owns_buffer) free(buffer);
+        if (owns_rewrite_ranges) free(rewrite_ranges);
+    }
+    
+#ifdef DEBUG_HIGHWATER
+    int highwater_store = 0;
+    int highwater_buffer = 0;
+#endif
+    
+    /// @brief Parses the provided mangled name and returns a newly allocated
+    /// demangling
+    ///
+    /// @param mangled_name Valid null-terminated C++ mangled name following
+    /// the Itanium C++ ABI mangling specification as implemented by Clang
+    ///
+    /// @result Newly allocated null-terminated demangled name when demangling
+    /// is succesful, and nullptr when demangling fails.  The caller is
+    /// responsible for freeing the allocated memory.
+    
+    char * GetDemangledCopy(const char * mangled_name,
+                            long mangled_name_length = 0)
+    {
+        if (!ParseMangling(mangled_name, mangled_name_length)) return nullptr;
+        
+#ifdef DEBUG_HIGHWATER
+        int rewrite_count = next_substitute_index +
+        (rewrite_ranges_size - 1 - next_template_arg_index);
+        int buffer_size = (int)(write_ptr - buffer);
+        if (rewrite_count > highwater_store) highwater_store = rewrite_count;
+        if (buffer_size > highwater_buffer) highwater_buffer = buffer_size;
+#endif
+        
+        int length = (int)(write_ptr - buffer);
+        char * copy = (char *)malloc(length + 1);
+        memcpy(copy, buffer, length);
+        copy[length] = '\0';
+        return copy;
+    }
+    
+private:
+    
+    //----------------------------------------------------
+    // Grow methods
+    //
+    // Manage the storage used during demangling
+    //----------------------------------------------------
+    
+    void GrowBuffer(long min_growth = 0)
+    {
+        // By default, double the size of the buffer
+        long growth = buffer_end - buffer;
+        
+        // Avoid growing by more than 1MB at a time
+        if (growth > 1 << 20) growth = 1 << 20;
+        
+        // ... but never grow by less than requested,
+        // or 1K, whichever is greater
+        if (min_growth < 1024) min_growth = 1024;
+        if (growth < min_growth) growth = min_growth;
+        
+        // Allocate the new buffer and migrate content
+        long new_size = (buffer_end - buffer) + growth;
+        char * new_buffer = (char *)malloc(new_size);
+        memcpy(new_buffer, buffer, write_ptr - buffer);
+        if (owns_buffer) free(buffer);
+        owns_buffer = true;
+        
+        // Update references to the new buffer
+        write_ptr = new_buffer + (write_ptr - buffer);
+        buffer = new_buffer;
+        buffer_end = buffer + new_size;
+    }
+    
+    void GrowRewriteRanges()
+    {
+        // By default, double the size of the array
+        int growth = rewrite_ranges_size;
+        
+        // Apply reasonable minimum and maximum sizes for growth
+        if (growth > 128) growth = 128;
+        if (growth < 16) growth = 16;
+        
+        // Allocate the new array and migrate content
+        int bytes = (rewrite_ranges_size + growth) * sizeof(BufferRange);
+        BufferRange * new_ranges = (BufferRange *) malloc(bytes);
+        for (int index = 0; index < next_substitute_index; index++)
+        {
+            new_ranges[index] = rewrite_ranges[index];
+        }
+        for (int index = rewrite_ranges_size - 1;
+             index > next_template_arg_index; index--)
+        {
+            new_ranges[index + growth] = rewrite_ranges[index];
+        }
+        if (owns_rewrite_ranges) free(rewrite_ranges);
+        owns_rewrite_ranges = true;
+        
+        // Update references to the new array
+        rewrite_ranges = new_ranges;
+        rewrite_ranges_size += growth;
+        next_template_arg_index += growth;
+    }
+    
+    //----------------------------------------------------
+    // Range and state management
+    //----------------------------------------------------
+    
+    int GetStartCookie()
+    {
+        return (int)(write_ptr - buffer);
+    }
+    
+    BufferRange EndRange(int start_cookie)
+    {
+        return { start_cookie, (int)(write_ptr - (buffer + start_cookie)) };
+    }
+    
+    void ReorderRange(BufferRange source_range, int insertion_point_cookie)
+    {
+        // Ensure there's room the preserve the source range
+        if (write_ptr + source_range.length > buffer_end)
+        {
+            GrowBuffer(write_ptr + source_range.length - buffer_end);
+        }
+        
+        // Reorder the content
+        memcpy(write_ptr, buffer + source_range.offset, source_range.length);
+        memmove(buffer + insertion_point_cookie + source_range.length,
+                buffer + insertion_point_cookie,
+                source_range.offset - insertion_point_cookie);
+        memcpy(buffer + insertion_point_cookie, write_ptr, source_range.length);
+        
+        // Fix up rewritable ranges, covering both substitutions and templates
+        int index = 0;
+        while (true)
+        {
+            if (index == next_substitute_index) index = next_template_arg_index + 1;
+            if (index == rewrite_ranges_size) break;
+            
+            // Affected ranges are either shuffled forward when after the
+            // insertion but before the source, or backward when inside the
+            // source
+            int candidate_offset = rewrite_ranges[index].offset;
+            if (candidate_offset >= insertion_point_cookie)
+            {
+                if (candidate_offset < source_range.offset)
+                {
+                    rewrite_ranges[index].offset += source_range.length;
+                }
+                else if (candidate_offset >= source_range.offset)
+                {
+                    rewrite_ranges[index].offset -=
+                    (source_range.offset - insertion_point_cookie);
+                }
+            }
+            ++index;
+        }
+    }
+    
+    void EndSubstitution(int start_cookie)
+    {
+        if (next_substitute_index == next_template_arg_index) GrowRewriteRanges();
+        
+        int index = next_substitute_index++;
+        rewrite_ranges[index] = EndRange(start_cookie);
+#ifdef DEBUG_SUBSTITUTIONS
+        printf("Saved substitution # %d = %.*s\n", index,
+               rewrite_ranges[index].length, buffer + start_cookie);
+#endif
+    }
+    
+    void EndTemplateArg(int start_cookie)
+    {
+        if (next_substitute_index == next_template_arg_index) GrowRewriteRanges();
+        
+        int index = next_template_arg_index--;
+        rewrite_ranges[index] = EndRange(start_cookie);
+#ifdef DEBUG_TEMPLATE_ARGS
+        printf("Saved template arg # %d = %.*s\n",
+               rewrite_ranges_size - index - 1,
+               rewrite_ranges[index].length, buffer + start_cookie);
+#endif
+    }
+    
+    void ResetTemplateArgs()
+    {
+        //TODO: this works, but is it the right thing to do?
+        // Should we push/pop somehow at the call sites?
+        next_template_arg_index = rewrite_ranges_size - 1;
+    }
+    
+    //----------------------------------------------------
+    // Write methods
+    //
+    // Appends content to the existing output buffer
+    //----------------------------------------------------
+    
+    void Write(char character)
+    {
+        if (write_ptr == buffer_end) GrowBuffer();
+        *write_ptr++ = character;
+    }
+    
+    void Write(const char * content)
+    {
+        Write(content, strlen(content));
+    }
+    
+    void Write(const char * content, long content_length)
+    {
+        char * end_write_ptr = write_ptr + content_length;
+        if (end_write_ptr > buffer_end)
+        {
+            GrowBuffer(end_write_ptr - buffer_end);
+            end_write_ptr = write_ptr + content_length;
+        }
+        memcpy(write_ptr, content, content_length);
+        write_ptr = end_write_ptr;
+    }
+#define WRITE(x) Write(x, sizeof(x) - 1)
+    
+    void WriteTemplateStart()
+    {
+        Write('<');
+    }
+    
+    void WriteTemplateEnd()
+    {
+        // Put a space between terminal > characters when nesting templates
+        if (write_ptr != buffer && *(write_ptr - 1) == '>') WRITE(" >");
+        else Write('>');
+    }
+    
+    void WriteCommaSpace()
+    {
+        WRITE(", ");
+    }
+    
+    void WriteNamespaceSeparator()
+    {
+        WRITE("::");
+    }
+    
+    void WriteStdPrefix()
+    {
+        WRITE("std::");
+    }
+    
+    void WriteQualifiers(int qualifiers, bool space_before_reference = true)
+    {
+        if (qualifiers & QualifierPointer) Write('*');
+        if (qualifiers & QualifierConst) WRITE(" const");
+        if (qualifiers & QualifierVolatile) WRITE(" volatile");
+        if (qualifiers & QualifierRestrict) WRITE(" restrict");
+        if (qualifiers & QualifierReference)
+        {
+            if (space_before_reference) WRITE(" &");
+            else Write('&');
+        }
+        if (qualifiers & QualifierRValueReference)
+        {
+            if (space_before_reference) WRITE(" &&");
+            else WRITE("&&");
+        }
+    }
+    
+    //----------------------------------------------------
+    // Rewrite methods
+    //
+    // Write another copy of content already present
+    // earlier in the output buffer
+    //----------------------------------------------------
+    
+    void RewriteRange(BufferRange range)
+    {
+        Write(buffer + range.offset, range.length);
+    }
+    
+    bool RewriteSubstitution(int index)
+    {
+        if (index < 0 || index >= next_substitute_index)
+        {
+#ifdef DEBUG_FAILURES
+            printf("*** Invalid substitution #%d\n", index);
+#endif
+            return false;
+        }
+        RewriteRange(rewrite_ranges[index]);
+        return true;
+    }
+    
+    bool RewriteTemplateArg(int template_index)
+    {
+        int index = rewrite_ranges_size - 1 - template_index;
+        if (template_index < 0 || index <= next_template_arg_index)
+        {
+#ifdef DEBUG_FAILURES
+            printf("*** Invalid template arg reference #%d\n", template_index);
+#endif
+            return false;
+        }
+        RewriteRange(rewrite_ranges[index]);
+        return true;
+    }
+    
+    //----------------------------------------------------
+    // TryParse methods
+    //
+    // Provide information with return values instead of
+    // writing to the output buffer
+    //
+    // Values indicating failure guarantee that the pre-
+    // call read_ptr is unchanged
+    //----------------------------------------------------
+    
+    int TryParseNumber()
+    {
+        unsigned char digit = *read_ptr - '0';
+        if (digit > 9) return -1;
+        
+        int count = digit;
+        while (true)
+        {
+            digit = *++read_ptr - '0';
+            if (digit > 9) break;
+            
+            count = count * 10 + digit;
+        }
+        return count;
+    }
+    
+    int TryParseBase36Number()
+    {
+        char digit = *read_ptr;
+        int count;
+        if (digit >= '0' && digit <= '9') count = digit -= '0';
+        else if (digit >= 'A' && digit <= 'Z') count = digit -= ('A' - 10);
+        else return -1;
+        
+        while (true)
+        {
+            digit = *++read_ptr;
+            if (digit >= '0' && digit <= '9') digit -= '0';
+            else if (digit >= 'A' && digit <= 'Z') digit -= ('A' - 10);
+            else break;
+            
+            count = count * 36 + digit;
+        }
+        return count;
+    }
+    
+    // <builtin-type> ::= v    # void
+    //                ::= w    # wchar_t
+    //                ::= b    # bool
+    //                ::= c    # char
+    //                ::= a    # signed char
+    //                ::= h    # unsigned char
+    //                ::= s    # short
+    //                ::= t    # unsigned short
+    //                ::= i    # int
+    //                ::= j    # unsigned int
+    //                ::= l    # long
+    //                ::= m    # unsigned long
+    //                ::= x    # long long, __int64
+    //                ::= y    # unsigned long long, __int64
+    //                ::= n    # __int128
+    //                ::= o    # unsigned __int128
+    //                ::= f    # float
+    //                ::= d    # double
+    //                ::= e    # long double, __float80
+    //                ::= g    # __float128
+    //                ::= z    # ellipsis
+    //                ::= Dd   # IEEE 754r decimal floating point (64 bits)
+    //                ::= De   # IEEE 754r decimal floating point (128 bits)
+    //                ::= Df   # IEEE 754r decimal floating point (32 bits)
+    //                ::= Dh   # IEEE 754r half-precision floating point (16 bits)
+    //                ::= Di   # char32_t
+    //                ::= Ds   # char16_t
+    //                ::= Da   # auto (in dependent new-expressions)
+    //                ::= Dn   # std::nullptr_t (i.e., decltype(nullptr))
+    //                ::= u <source-name>    # vendor extended type
+    
+    const char * TryParseBuiltinType()
+    {
+        switch (*read_ptr++)
+        {
+            case 'v': return "void";
+            case 'w': return "wchar_t";
+            case 'b': return "bool";
+            case 'c': return "char";
+            case 'a': return "signed char";
+            case 'h': return "unsigned char";
+            case 's': return "short";
+            case 't': return "unsigned short";
+            case 'i': return "int";
+            case 'j': return "unsigned int";
+            case 'l': return "long";
+            case 'm': return "unsigned long";
+            case 'x': return "long long";
+            case 'y': return "unsigned long long";
+            case 'n': return "__int128";
+            case 'o': return "unsigned __int128";
+            case 'f': return "float";
+            case 'd': return "double";
+            case 'e': return "long double";
+            case 'g': return "__float128";
+            case 'z': return "...";
+            case 'D':
+            {
+                switch (*read_ptr++)
+                {
+                    case 'd': return "decimal64";
+                    case 'e': return "decimal128";
+                    case 'f': return "decimal32";
+                    case 'h': return "decimal16";
+                    case 'i': return "char32_t";
+                    case 's': return "char16_t";
+                    case 'a': return "auto";
+                    case 'c': return "decltype(auto)";
+                    case 'n': return "std::nullptr_t";
+                    default:
+                        --read_ptr;
+                }
+            }
+        }
+        --read_ptr;
+        return nullptr;
+    }
+    
+    //   <operator-name>
+    //                   ::= aa    # &&
+    //                   ::= ad    # & (unary)
+    //                   ::= an    # &
+    //                   ::= aN    # &=
+    //                   ::= aS    # =
+    //                   ::= cl    # ()
+    //                   ::= cm    # ,
+    //                   ::= co    # ~
+    //                   ::= da    # delete[]
+    //                   ::= de    # * (unary)
+    //                   ::= dl    # delete
+    //                   ::= dv    # /
+    //                   ::= dV    # /=
+    //                   ::= eo    # ^
+    //                   ::= eO    # ^=
+    //                   ::= eq    # ==
+    //                   ::= ge    # >=
+    //                   ::= gt    # >
+    //                   ::= ix    # []
+    //                   ::= le    # <=
+    //                   ::= ls    # <<
+    //                   ::= lS    # <<=
+    //                   ::= lt    # <
+    //                   ::= mi    # -
+    //                   ::= mI    # -=
+    //                   ::= ml    # *
+    //                   ::= mL    # *=
+    //                   ::= mm    # -- (postfix in <expression> context)
+    //                   ::= na    # new[]
+    //                   ::= ne    # !=
+    //                   ::= ng    # - (unary)
+    //                   ::= nt    # !
+    //                   ::= nw    # new
+    //                   ::= oo    # ||
+    //                   ::= or    # |
+    //                   ::= oR    # |=
+    //                   ::= pm    # ->*
+    //                   ::= pl    # +
+    //                   ::= pL    # +=
+    //                   ::= pp    # ++ (postfix in <expression> context)
+    //                   ::= ps    # + (unary)
+    //                   ::= pt    # ->
+    //                   ::= qu    # ?
+    //                   ::= rm    # %
+    //                   ::= rM    # %=
+    //                   ::= rs    # >>
+    //                   ::= rS    # >>=
+    //                   ::= cv <type>    # (cast)
+    //                   ::= v <digit> <source-name>        # vendor extended operator
+    
+    Operator TryParseOperator()
+    {
+        switch (*read_ptr++)
+        {
+            case 'a':
+                switch (*read_ptr++)
+            {
+                case 'a': return { "&&", OperatorKind::Binary };
+                case 'd': return { "&", OperatorKind::Unary };
+                case 'n': return { "&", OperatorKind::Binary };
+                case 'N': return { "&=", OperatorKind::Binary };
+                case 'S': return { "=", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'c':
+                switch (*read_ptr++)
+            {
+                case 'l': return { "()", OperatorKind::Other };
+                case 'm': return { ",", OperatorKind::Other };
+                case 'o': return { "~", OperatorKind::Unary };
+                case 'v': return { nullptr, OperatorKind::ConversionOperator };
+            }
+                --read_ptr;
+                break;
+            case 'd':
+                switch (*read_ptr++)
+            {
+                case 'a': return { " delete[]", OperatorKind::Other };
+                case 'e': return { "*", OperatorKind::Unary };
+                case 'l': return { " delete", OperatorKind::Other };
+                case 'v': return { "/", OperatorKind::Binary };
+                case 'V': return { "/=", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'e':
+                switch (*read_ptr++)
+            {
+                case 'o': return { "^", OperatorKind::Binary };
+                case 'O': return { "^=", OperatorKind::Binary };
+                case 'q': return { "==", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'g':
+                switch (*read_ptr++)
+            {
+                case 'e': return { ">=", OperatorKind::Binary };
+                case 't': return { ">", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'i':
+                switch (*read_ptr++)
+            {
+                case 'x': return { "[]", OperatorKind::Other };
+            }
+                --read_ptr;
+                break;
+            case 'l':
+                switch (*read_ptr++)
+            {
+                case 'e': return { "<=", OperatorKind::Binary };
+                case 's': return { "<<", OperatorKind::Binary };
+                case 'S': return { "<<=", OperatorKind::Binary };
+                case 't': return { "<", OperatorKind::Binary };
+                    // case 'i': return { "?", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'm':
+                switch (*read_ptr++)
+            {
+                case 'i': return { "-", OperatorKind::Binary };
+                case 'I': return { "-=", OperatorKind::Binary };
+                case 'l': return { "*", OperatorKind::Binary };
+                case 'L': return { "*=", OperatorKind::Binary };
+                case 'm': return { "--", OperatorKind::Postfix };
+            }
+                --read_ptr;
+                break;
+            case 'n':
+                switch (*read_ptr++)
+            {
+                case 'a': return { " new[]", OperatorKind::Other };
+                case 'e': return { "!=", OperatorKind::Binary };
+                case 'g': return { "-", OperatorKind::Unary };
+                case 't': return { "!", OperatorKind::Unary };
+                case 'w': return { " new", OperatorKind::Other };
+            }
+                --read_ptr;
+                break;
+            case 'o':
+                switch (*read_ptr++)
+            {
+                case 'o': return { "||", OperatorKind::Binary };
+                case 'r': return { "|", OperatorKind::Binary };
+                case 'R': return { "|=", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'p':
+                switch (*read_ptr++)
+            {
+                case 'm': return { "->*", OperatorKind::Binary };
+                case 's': return { "+", OperatorKind::Unary };
+                case 'l': return { "+", OperatorKind::Binary };
+                case 'L': return { "+=", OperatorKind::Binary };
+                case 'p': return { "++", OperatorKind::Postfix };
+                case 't': return { "->", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'q':
+                switch (*read_ptr++)
+            {
+                case 'u': return { "?", OperatorKind::Ternary };
+            }
+                --read_ptr;
+                break;
+            case 'r':
+                switch (*read_ptr++)
+            {
+                case 'm': return { "%", OperatorKind::Binary };
+                case 'M': return { "%=", OperatorKind::Binary };
+                case 's': return { ">>", OperatorKind::Binary };
+                case 'S': return { ">=", OperatorKind::Binary };
+            }
+                --read_ptr;
+                break;
+            case 'v':
+                char digit = *read_ptr;
+                if (digit >= '0' && digit <= '9')
+                {
+                    read_ptr++;
+                    return { nullptr, OperatorKind::Vendor };
+                }
+                --read_ptr;
+                break;
+        }
+        --read_ptr;
+        return { nullptr, OperatorKind::NoMatch };
+    }
+    
+    // <CV-qualifiers> ::= [r] [V] [K]
+    // <ref-qualifier> ::= R                   # & ref-qualifier
+    // <ref-qualifier> ::= O                   # && ref-qualifier
+    
+    int TryParseQualifiers(bool allow_cv, bool allow_ro)
+    {
+        int qualifiers = QualifierNone;
+        char next = *read_ptr;
+        if (allow_cv)
+        {
+            if (next == 'r') // restrict
+            {
+                qualifiers |= QualifierRestrict;
+                next = *++read_ptr;
+            }
+            if (next == 'V') // volatile
+            {
+                qualifiers |= QualifierVolatile;
+                next = *++read_ptr;
+            }
+            if (next == 'K') // const
+            {
+                qualifiers |= QualifierConst;
+                next = *++read_ptr;
+            }
+        }
+        if (allow_ro)
+        {
+            if (next == 'R')
+            {
+                ++read_ptr;
+                qualifiers |= QualifierReference;
+            }
+            else if (next =='O')
+            {
+                ++read_ptr;
+                qualifiers |= QualifierRValueReference;
+            }
+        }
+        return qualifiers;
+    }
+    
+    // <discriminator> := _ <non-negative number>      # when number < 10
+    //                 := __ <non-negative number> _   # when number >= 10
+    //  extension      := decimal-digit+
+    
+    int TryParseDiscriminator()
+    {
+        const char * discriminator_start = read_ptr;
+        
+        // Test the extension first, since it's what Clang uses
+        int discriminator_value = TryParseNumber();
+        if (discriminator_value != -1) return discriminator_value;
+        
+        char next = *read_ptr;
+        if (next == '_')
+        {
+            next = *++read_ptr;
+            if (next == '_')
+            {
+                ++read_ptr;
+                discriminator_value = TryParseNumber();
+                if (discriminator_value != -1 && *read_ptr++ != '_')
+                {
+                    return discriminator_value;
+                }
+            }
+            else if (next >= '0' && next <= '9')
+            {
+                ++read_ptr;
+                return next - '0';
+            }
+        }
+        
+        // Not a valid discriminator
+        read_ptr = discriminator_start;
+        return -1;
+    }
+    
+    //----------------------------------------------------
+    // Parse methods
+    //
+    // Consume input starting from read_ptr and produce
+    // buffered output at write_ptr
+    //
+    // Failures return false and may leave read_ptr in an
+    // indeterminate state
+    //----------------------------------------------------
+    
+    bool Parse(char character)
+    {
+        if (*read_ptr++ == character) return true;
+#ifdef DEBUG_FAILURES
+        printf("*** Expected '%c'\n", character);
+#endif
+        return false;
+    }
+    
+    // <number> ::= [n] <non-negative decimal integer>
+    
+    bool ParseNumber(bool allow_negative = false)
+    {
+        if (allow_negative && *read_ptr == 'n')
+        {
+            Write('-');
+            ++read_ptr;
+        }
+        const char * before_digits = read_ptr;
+        while (true)
+        {
+            unsigned char digit = *read_ptr - '0';
+            if (digit > 9) break;
+            ++read_ptr;
+        }
+        if (int digit_count = (int)(read_ptr - before_digits))
+        {
+            Write(before_digits, digit_count);
+            return true;
+        }
+#ifdef DEBUG_FAILURES
+        printf("*** Expected number\n");
+#endif
+        return false;
+    }
+    
+    // <substitution> ::= S <seq-id> _
+    //                ::= S_
+    // <substitution> ::= Sa # ::std::allocator
+    // <substitution> ::= Sb # ::std::basic_string
+    // <substitution> ::= Ss # ::std::basic_string < char,
+    //                                               ::std::char_traits<char>,
+    //                                               ::std::allocator<char> >
+    // <substitution> ::= Si # ::std::basic_istream<char,  std::char_traits<char> >
+    // <substitution> ::= So # ::std::basic_ostream<char,  std::char_traits<char> >
+    // <substitution> ::= Sd # ::std::basic_iostream<char, std::char_traits<char> >
+    
+    bool ParseSubstitution()
+    {
+        const char * substitution;
+        switch (*read_ptr)
+        {
+            case 'a': substitution = "std::allocator"; break;
+            case 'b': substitution = "std::basic_string"; break;
+            case 's': substitution = "std::string"; break;
+            case 'i': substitution = "std::istream"; break;
+            case 'o': substitution = "std::ostream"; break;
+            case 'd': substitution = "std::iostream"; break;
+            default:
+                // A failed attempt to parse a number will return -1 which turns out to be
+                // perfect here as S_ is the first substitution, S0_ the next and so forth
+                int substitution_index = TryParseBase36Number();
+                if (*read_ptr++ != '_')
+                {
+#ifdef DEBUG_FAILURES
+                    printf("*** Expected terminal _ in substitution\n");
+#endif
+                    return false;
+                }
+                return RewriteSubstitution(substitution_index + 1);
+        }
+        Write(substitution);
+        ++read_ptr;
+        return true;
+    }
+    
+    // <function-type> ::= F [Y] <bare-function-type> [<ref-qualifier>] E
+    //
+    // <bare-function-type> ::= <signature type>+      # types are possible return type, then parameter types
+    
+    bool ParseFunctionType(int inner_qualifiers = QualifierNone)
+    {
+#ifdef DEBUG_FAILURES
+        printf("*** Function types not supported\n");
+#endif
+        //TODO: first steps toward an implementation follow, but they're far
+        // from complete.  Function types tend to bracket other types eg:
+        // int (*)() when used as the type for "name" becomes int (*name)().
+        // This makes substitution et al ... interesting.
+        return false;
+        
+        if (*read_ptr == 'Y') ++read_ptr;;
+        
+        int return_type_start_cookie = GetStartCookie();
+        if (!ParseType()) return false;
+        Write(' ');
+        
+        int insert_cookie = GetStartCookie();
+        Write('(');
+        bool first_param = true;
+        int qualifiers = QualifierNone;
+        while (true)
+        {
+            switch (*read_ptr)
+            {
+                case 'E':
+                    ++read_ptr;
+                    Write(')');
+                    break;
+                case 'v':
+                    ++read_ptr;
+                    continue;
+                case 'R':
+                case 'O':
+                    if (*(read_ptr + 1) == 'E')
+                    {
+                        qualifiers = TryParseQualifiers(false, true);
+                        Parse('E');
+                        break;
+                    }
+                    // fallthrough
+                default:
+                {
+                    if (first_param) first_param = false;
+                    else WriteCommaSpace();
+                    
+                    if (!ParseType()) return false;
+                    continue;
+                }
+            }
+            break;
+        }
+        
+        if (qualifiers)
+        {
+            WriteQualifiers(qualifiers);
+            EndSubstitution(return_type_start_cookie);
+        }
+        
+        if (inner_qualifiers)
+        {
+            int qualifier_start_cookie = GetStartCookie();
+            Write('(');
+            WriteQualifiers(inner_qualifiers);
+            Write(')');
+            ReorderRange(EndRange(qualifier_start_cookie), insert_cookie);
+        }
+        return true;
+    }
+    
+    // <array-type> ::= A <positive dimension number> _ <element type>
+    //              ::= A [<dimension expression>] _ <element type>
+    
+    bool ParseArrayType(int qualifiers = QualifierNone)
+    {
+#ifdef DEBUG_FAILURES
+        printf("*** Array type unsupported\n");
+#endif
+        //TODO: We fail horribly when recalling these as substitutions or
+        // templates and trying to constify them eg:
+        // _ZN4llvm2cl5applyIA28_cNS0_3optIbLb0ENS0_6parserIbEEEEEEvRKT_PT0_
+        //
+        //TODO: Chances are we don't do any better with references and pointers
+        // that should be type (&) [] instead of type & []
+        
+        return false;
+        
+        if (*read_ptr == '_')
+        {
+            ++read_ptr;
+            if (!ParseType()) return false;
+            if (qualifiers) WriteQualifiers(qualifiers);
+            WRITE(" []");
+            return true;
+        }
+        else
+        {
+            const char * before_digits = read_ptr;
+            if (TryParseNumber() != -1)
+            {
+                const char * after_digits = read_ptr;
+                if (!Parse('_')) return false;
+                if (!ParseType()) return false;
+                if (qualifiers) WriteQualifiers(qualifiers);
+                Write(' ');
+                Write('[');
+                Write(before_digits, after_digits - before_digits);
+            }
+            else
+            {
+                int type_insertion_cookie = GetStartCookie();
+                if (!ParseExpression()) return false;
+                if (!Parse('_')) return false;
+                
+                int type_start_cookie = GetStartCookie();
+                if (!ParseType()) return false;
+                if (qualifiers) WriteQualifiers(qualifiers);
+                Write(' ');
+                Write('[');
+                ReorderRange(EndRange(type_start_cookie), type_insertion_cookie);
+            }
+            Write(']');
+            return true;
+        }
+    }
+    
+    // <pointer-to-member-type> ::= M <class type> <member type>
+    
+    //TODO: Determine how to handle pointers to function members correctly,
+    // currently not an issue because we don't have function types at all...
+    bool ParsePointerToMemberType()
+    {
+        int insertion_cookie = GetStartCookie();
+        Write(' ');
+        if (!ParseType()) return false;
+        WRITE("::*");
+        
+        int type_cookie = GetStartCookie();
+        if (!ParseType()) return false;
+        ReorderRange(EndRange(type_cookie), insertion_cookie);
+        return true;
+    }
+    
+    // <template-param> ::= T_    # first template parameter
+    //                  ::= T <parameter-2 non-negative number> _
+    
+    bool ParseTemplateParam()
+    {
+        int count = TryParseNumber();
+        if (!Parse('_')) return false;
+        
+        // When no number is present we get -1, which is convenient since
+        // T_ is the zeroth element T0_ is element 1, and so on
+        return RewriteTemplateArg(count + 1);
+    }
+    
+    // <type> ::= <builtin-type>
+    //        ::= <function-type>
+    //        ::= <class-enum-type>
+    //        ::= <array-type>
+    //        ::= <pointer-to-member-type>
+    //        ::= <template-param>
+    //        ::= <template-template-param> <template-args>
+    //        ::= <decltype>
+    //        ::= <substitution>
+    //        ::= <CV-qualifiers> <type>
+    //        ::= P <type>        # pointer-to
+    //        ::= R <type>        # reference-to
+    //        ::= O <type>        # rvalue reference-to (C++0x)
+    //        ::= C <type>        # complex pair (C 2000)
+    //        ::= G <type>        # imaginary (C 2000)
+    //        ::= Dp <type>       # pack expansion (C++0x)
+    //        ::= U <source-name> <type>  # vendor extended type qualifier
+    // extension := U <objc-name> <objc-type>  # objc-type<identifier>
+    // extension := <vector-type> # <vector-type> starts with Dv
+    
+    // <objc-name> ::= <k0 number> objcproto <k1 number> <identifier>  # k0 = 9 + <number of digits in k1> + k1
+    // <objc-type> := <source-name>  # PU<11+>objcproto 11objc_object<source-name> 11objc_object -> id<source-name>
+    
+    bool ParseType()
+    {
+#ifdef DEBUG_FAILURES
+        const char * failed_type = read_ptr;
+#endif
+        int type_start_cookie = GetStartCookie();
+        bool suppress_substitution = false;
+        
+        int qualifiers = TryParseQualifiers(true, false);
+        switch (*read_ptr)
+        {
+            case 'D':
+                ++read_ptr;
+                switch (*read_ptr++)
+            {
+                case 'p':
+                    if (!ParseType()) return false;
+                    break;
+                case 'T':
+                case 't':
+                case 'v':
+                default:
+#ifdef DEBUG_FAILURES
+                    printf("*** Unsupported type: %.3s\n", failed_type);
+#endif
+                    return false;
+            }
+                break;
+            case 'T':
+                ++read_ptr;
+                if (!ParseTemplateParam()) return false;
+                break;
+            case 'M':
+                ++read_ptr;
+                if (!ParsePointerToMemberType()) return false;
+                break;
+            case 'A':
+                ++read_ptr;
+                if (!ParseArrayType()) return false;
+                break;
+            case 'F':
+                ++read_ptr;
+                if (!ParseFunctionType()) return false;
+                break;
+            case 'S':
+                if (*++read_ptr == 't')
+                {
+                    ++read_ptr;
+                    WriteStdPrefix();
+                    if (!ParseName()) return false;
+                }
+                else
+                {
+                    suppress_substitution = true;
+                    if (!ParseSubstitution()) return false;
+                }
+                break;
+            case 'P':
+            {
+                switch (*++read_ptr)
+                {
+                    case 'F':
+                        ++read_ptr;
+                        if (!ParseFunctionType(QualifierPointer)) return false;
+                        break;
+                    default:
+                        if (!ParseType()) return false;
+                        Write('*');
+                        break;
+                }
+                break;
+            }
+            case 'R':
+            {
+                ++read_ptr;
+                if (!ParseType()) return false;
+                Write('&');
+                break;
+            }
+            case 'O':
+            {
+                ++read_ptr;
+                if (!ParseType()) return false;
+                Write('&');
+                Write('&');
+                break;
+            }
+            case 'C':
+            case 'G':
+            case 'U':
+#ifdef DEBUG_FAILURES
+                printf("*** Unsupported type: %.3s\n", failed_type);
+#endif
+                return false;
+                // Test for common cases to avoid TryParseBuiltinType() overhead
+            case 'N':
+            case 'Z':
+            case 'L':
+                if (!ParseName()) return false;
+                break;
+            default:
+                if (const char * builtin = TryParseBuiltinType())
+                {
+                    Write(builtin);
+                    suppress_substitution = true;
+                }
+                else
+                {
+                    if (!ParseName()) return false;
+                }
+                break;
+        }
+        
+        // Allow base substitutions to be suppressed, but always record
+        // substitutions for the qualified variant
+        if (!suppress_substitution) EndSubstitution(type_start_cookie);
+        if (qualifiers)
+        {
+            WriteQualifiers(qualifiers, false);
+            EndSubstitution(type_start_cookie);
+        }
+        return true;
+    }
+    
+    // <unnamed-type-name> ::= Ut [ <nonnegative number> ] _
+    //                     ::= <closure-type-name>
+    //
+    // <closure-type-name> ::= Ul <lambda-sig> E [ <nonnegative number> ] _
+    //
+    // <lambda-sig> ::= <parameter type>+  # Parameter types or "v" if the lambda has no parameters
+    
+    bool ParseUnnamedTypeName(NameState & name_state)
+    {
+        switch (*read_ptr++)
+        {
+            case 't':
+            {
+                int cookie = GetStartCookie();
+                WRITE("'unnamed");
+                const char * before_digits = read_ptr;
+                if (TryParseNumber() != -1) Write(before_digits,
+                                                  read_ptr - before_digits);
+                if (!Parse('_')) return false;
+                Write('\'');
+                name_state.last_name_range = EndRange(cookie);
+                return true;
+            }
+            case 'b':
+            {
+                int cookie = GetStartCookie();
+                WRITE("'block");
+                const char * before_digits = read_ptr;
+                if (TryParseNumber() != -1) Write(before_digits,
+                                                  read_ptr - before_digits);
+                if (!Parse('_')) return false;
+                Write('\'');
+                name_state.last_name_range = EndRange(cookie);
+                return true;
+            }
+            case 'l':
+#ifdef DEBUG_FAILURES
+                printf("*** Lambda type names unsupported\n");
+#endif
+                return false;
+        }
+#ifdef DEBUG_FAILURES
+        printf("*** Unknown unnamed type %.3s\n", read_ptr - 2);
+#endif
+        return false;
+    }
+    
+    // <ctor-dtor-name> ::= C1      # complete object constructor
+    //                  ::= C2      # base object constructor
+    //                  ::= C3      # complete object allocating constructor
+    
+    bool ParseCtor(NameState & name_state)
+    {
+        char next = *read_ptr;
+        if (next == '1' || next == '2' || next == '3' || next == '5')
+        {
+            RewriteRange(name_state.last_name_range);
+            name_state.has_no_return_type = true;
+            ++read_ptr;
+            return true;
+        }
+#ifdef DEBUG_FAILURES
+        printf("*** Broken constructor\n");
+#endif
+        return false;
+    }
+    
+    // <ctor-dtor-name> ::= D0      # deleting destructor
+    //                  ::= D1      # complete object destructor
+    //                  ::= D2      # base object destructor
+    
+    bool ParseDtor(NameState & name_state)
+    {
+        char next = *read_ptr;
+        if (next == '0' || next == '1' || next == '2' || next == '5')
+        {
+            Write('~');
+            RewriteRange(name_state.last_name_range);
+            name_state.has_no_return_type = true;
+            ++read_ptr;
+            return true;
+        }
+#ifdef DEBUG_FAILURES
+        printf("*** Broken destructor\n");
+#endif
+        return false;
+    }
+    
+    // See TryParseOperator()
+    
+    bool ParseOperatorName(NameState & name_state)
+    {
+#ifdef DEBUG_FAILURES
+        const char * operator_ptr = read_ptr;
+#endif
+        Operator parsed_operator = TryParseOperator();
+        if (parsed_operator.name)
+        {
+            WRITE("operator");
+            Write(parsed_operator.name);
+            return true;
+        }
+        
+        // Handle special operators
+        switch (parsed_operator.kind)
+        {
+            case OperatorKind::Vendor:
+                WRITE("operator ");
+                return ParseSourceName();
+            case OperatorKind::ConversionOperator:
+                ResetTemplateArgs();
+                name_state.has_no_return_type = true;
+                WRITE("operator ");
+                return ParseType();
+            default:
+#ifdef DEBUG_FAILURES
+                printf("*** Unknown operator: %.2s\n", operator_ptr);
+#endif
+                return false;
+        }
+    }
+    
+    // <source-name> ::= <positive length number> <identifier>
+    
+    bool ParseSourceName()
+    {
+        int count = TryParseNumber();
+        if (count == -1)
+        {
+#ifdef DEBUG_FAILURES
+            printf("*** Malformed source name, missing length count\n");
+#endif
+            return false;
+        }
+        
+        const char * next_read_ptr = read_ptr + count;
+        if (next_read_ptr > read_end)
+        {
+#ifdef DEBUG_FAILURES
+            printf("*** Malformed source name, premature termination\n");
+#endif
+            return false;
+        }
+        
+        if (count >= 10 && strncmp(read_ptr, "_GLOBAL__N", 10) == 0) WRITE("(anonymous namespace)");
+        else Write(read_ptr, count);
+        
+        read_ptr = next_read_ptr;
+        return true;
+    }
+    
+    // <unqualified-name> ::= <operator-name>
+    //                    ::= <ctor-dtor-name>
+    //                    ::= <source-name>
+    //                    ::= <unnamed-type-name>
+    
+    bool ParseUnqualifiedName(NameState & name_state)
+    {
+        // Note that these are detected directly in ParseNestedName for
+        // performance rather than switching on the same options twice
+        char next = *read_ptr;
+        switch (next)
+        {
+            case 'C':
+                ++read_ptr;
+                return ParseCtor(name_state);
+            case 'D':
+                ++read_ptr;
+                return ParseDtor(name_state);
+            case 'U':
+                ++read_ptr;
+                return ParseUnnamedTypeName(name_state);
+            case '0':
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+            {
+                int name_start_cookie = GetStartCookie();
+                if (!ParseSourceName()) return false;
+                name_state.last_name_range = EndRange(name_start_cookie);
+                return true;
+            }
+            default:
+                return ParseOperatorName(name_state);
+        };
+    }
+    
+    // <unscoped-name> ::= <unqualified-name>
+    //                 ::= St <unqualified-name>   # ::std::
+    // extension       ::= StL<unqualified-name>
+    
+    bool ParseUnscopedName(NameState & name_state)
+    {
+        if (*read_ptr == 'S' && *(read_ptr + 1) == 't')
+        {
+            WriteStdPrefix();
+            if (*(read_ptr += 2) == 'L') ++read_ptr;
+        }
+        return ParseUnqualifiedName(name_state);
+    }
+    
+    bool ParseIntegerLiteral(const char * prefix, const char * suffix,
+                             bool allow_negative)
+    {
+        if (prefix) Write(prefix);
+        if (!ParseNumber(allow_negative)) return false;
+        if (suffix) Write(suffix);
+        return Parse('E');
+    }
+    
+    bool ParseBooleanLiteral()
+    {
+        switch (*read_ptr++)
+        {
+            case '0': WRITE("false"); break;
+            case '1': WRITE("true"); break;
+            default:
+#ifdef DEBUG_FAILURES
+                printf("*** Boolean literal not 0 or 1\n");
+#endif
+                return false;
+        }
+        return Parse('E');
+    }
+    
+    // <expr-primary> ::= L <type> <value number> E                          # integer literal
+    //                ::= L <type> <value float> E                           # floating literal
+    //                ::= L <string type> E                                  # string literal
+    //                ::= L <nullptr type> E                                 # nullptr literal (i.e., "LDnE")
+    //                ::= L <type> <real-part float> _ <imag-part float> E   # complex floating point literal (C 2000)
+    //                ::= L <mangled-name> E                                 # external name
+    
+    bool ParseExpressionPrimary()
+    {
+        switch (*read_ptr++)
+        {
+            case 'b': return ParseBooleanLiteral();
+            case 'x': return ParseIntegerLiteral(nullptr, "ll", true);
+            case 'l': return ParseIntegerLiteral(nullptr, "l", true);
+            case 'i': return ParseIntegerLiteral(nullptr, nullptr, true);
+            case 'n': return ParseIntegerLiteral("(__int128)", nullptr, true);
+            case 'j': return ParseIntegerLiteral(nullptr, "u", false);
+            case 'm': return ParseIntegerLiteral(nullptr, "ul", false);
+            case 'y': return ParseIntegerLiteral(nullptr, "ull", false);
+            case 'o': return ParseIntegerLiteral("(unsigned __int128)",
+                                                 nullptr, false);
+            case '_':
+                if (*read_ptr++ == 'Z')
+                {
+                    if (!ParseEncoding()) return false;
+                    return Parse('E');
+                }
+                --read_ptr;
+                // fallthrough
+            case 'w':
+            case 'c':
+            case 'a':
+            case 'h':
+            case 's':
+            case 't':
+            case 'f':
+            case 'd':
+            case 'e':
+#ifdef DEBUG_FAILURES
+                printf("*** Unsupported primary expression %.5s\n", read_ptr - 1);
+#endif
+                return false;
+            case 'T':
+                // Invalid mangled name per
+                //   http://sourcerytools.com/pipermail/cxx-abi-dev/2011-August/002422.html
+#ifdef DEBUG_FAILURES
+                printf("*** Invalid primary expr encoding\n");
+#endif
+                return false;
+            default:
+                --read_ptr;
+                Write('(');
+                if (!ParseType()) return false;
+                Write(')');
+                if (!ParseNumber()) return false;
+                return Parse('E');
+        }
+    }
+    
+    // <unresolved-type> ::= <template-param>
+    //                   ::= <decltype>
+    //                   ::= <substitution>
+    
+    bool ParseUnresolvedType()
+    {
+        int type_start_cookie = GetStartCookie();
+        switch (*read_ptr++)
+        {
+            case 'T':
+                if (!ParseTemplateParam()) return false;
+                EndSubstitution(type_start_cookie);
+                return true;
+            case 'S':
+            {
+                if (*read_ptr != 't') return ParseSubstitution();
+                
+                ++read_ptr;
+                WriteStdPrefix();
+                NameState type_name = {};
+                if (!ParseUnqualifiedName(type_name)) return false;
+                EndSubstitution(type_start_cookie);
+                return true;
+                
+            }
+            case 'D':
+            default:
+#ifdef DEBUG_FAILURES
+                printf("*** Unsupported unqualified type: %3s\n", read_ptr - 1);
+#endif
+                return false;
+        }
+    }
+    
+    // <base-unresolved-name> ::= <simple-id>                                # unresolved name
+    //          extension     ::= <operator-name>                            # unresolved operator-function-id
+    //          extension     ::= <operator-name> <template-args>            # unresolved operator template-id
+    //                        ::= on <operator-name>                         # unresolved operator-function-id
+    //                        ::= on <operator-name> <template-args>         # unresolved operator template-id
+    //                        ::= dn <destructor-name>                       # destructor or pseudo-destructor;
+    //                                                                         # e.g. ~X or ~X<N-1>
+    
+    bool ParseBaseUnresolvedName()
+    {
+#ifdef DEBUG_FAILURES
+        printf("*** Base unresolved name unsupported\n");
+#endif
+        return false;
+    }
+    
+    // <unresolved-name>
+    //  extension        ::= srN <unresolved-type> [<template-args>] <unresolved-qualifier-level>* E <base-unresolved-name>
+    //                   ::= [gs] <base-unresolved-name>                     # x or (with "gs") ::x
+    //                   ::= [gs] sr <unresolved-qualifier-level>+ E <base-unresolved-name>
+    //                                                                       # A::x, N::y, A<T>::z; "gs" means leading "::"
+    //                   ::= sr <unresolved-type> <base-unresolved-name>     # T::x / decltype(p)::x
+    //  extension        ::= sr <unresolved-type> <template-args> <base-unresolved-name>
+    //                                                                       # T::N::x /decltype(p)::N::x
+    //  (ignored)        ::= srN <unresolved-type>  <unresolved-qualifier-level>+ E <base-unresolved-name>
+    
+    bool ParseUnresolvedName()
+    {
+#ifdef DEBUG_FAILURES
+        printf("*** Unresolved names not supported\n");
+#endif
+        //TODO: grammar for all of this seems unclear...
+        return false;
+        
+        if (*read_ptr == 'g' && *(read_ptr + 1) == 's')
+        {
+            read_ptr += 2;
+            WriteNamespaceSeparator();
+        }
+    }
+    
+    // <expression> ::= <unary operator-name> <expression>
+    //              ::= <binary operator-name> <expression> <expression>
+    //              ::= <ternary operator-name> <expression> <expression> <expression>
+    //              ::= cl <expression>+ E                                   # call
+    //              ::= cv <type> <expression>                               # conversion with one argument
+    //              ::= cv <type> _ <expression>* E                          # conversion with a different number of arguments
+    //              ::= [gs] nw <expression>* _ <type> E                     # new (expr-list) type
+    //              ::= [gs] nw <expression>* _ <type> <initializer>         # new (expr-list) type (init)
+    //              ::= [gs] na <expression>* _ <type> E                     # new[] (expr-list) type
+    //              ::= [gs] na <expression>* _ <type> <initializer>         # new[] (expr-list) type (init)
+    //              ::= [gs] dl <expression>                                 # delete expression
+    //              ::= [gs] da <expression>                                 # delete[] expression
+    //              ::= pp_ <expression>                                     # prefix ++
+    //              ::= mm_ <expression>                                     # prefix --
+    //              ::= ti <type>                                            # typeid (type)
+    //              ::= te <expression>                                      # typeid (expression)
+    //              ::= dc <type> <expression>                               # dynamic_cast<type> (expression)
+    //              ::= sc <type> <expression>                               # static_cast<type> (expression)
+    //              ::= cc <type> <expression>                               # const_cast<type> (expression)
+    //              ::= rc <type> <expression>                               # reinterpret_cast<type> (expression)
+    //              ::= st <type>                                            # sizeof (a type)
+    //              ::= sz <expression>                                      # sizeof (an expression)
+    //              ::= at <type>                                            # alignof (a type)
+    //              ::= az <expression>                                      # alignof (an expression)
+    //              ::= nx <expression>                                      # noexcept (expression)
+    //              ::= <template-param>
+    //              ::= <function-param>
+    //              ::= dt <expression> <unresolved-name>                    # expr.name
+    //              ::= pt <expression> <unresolved-name>                    # expr->name
+    //              ::= ds <expression> <expression>                         # expr.*expr
+    //              ::= sZ <template-param>                                  # size of a parameter pack
+    //              ::= sZ <function-param>                                  # size of a function parameter pack
+    //              ::= sp <expression>                                      # pack expansion
+    //              ::= tw <expression>                                      # throw expression
+    //              ::= tr                                                   # throw with no operand (rethrow)
+    //              ::= <unresolved-name>                                    # f(p), N::f(p), ::f(p),
+    //                                                                       # freestanding dependent name (e.g., T::x),
+    //                                                                       # objectless nonstatic member reference
+    //              ::= <expr-primary>
+    
+    bool ParseExpression()
+    {
+        Operator expression_operator = TryParseOperator();
+        switch (expression_operator.kind)
+        {
+            case OperatorKind::Unary:
+                Write(expression_operator.name);
+                Write('(');
+                if (!ParseExpression()) return false;
+                Write(')');
+                return true;
+            case OperatorKind::Binary:
+                if (!ParseExpression()) return false;
+                Write(expression_operator.name);
+                return ParseExpression();
+            case OperatorKind::Ternary:
+                if (!ParseExpression()) return false;
+                Write('?');
+                if (!ParseExpression()) return false;
+                Write(':');
+                return ParseExpression();
+            case OperatorKind::NoMatch:
+                break;
+            case OperatorKind::Other:
+            default:
+#ifdef DEBUG_FAILURES
+                printf("*** Unsupported operator: %s\n", expression_operator.name);
+#endif
+                return false;
+        }
+        
+        switch (*read_ptr++)
+        {
+            case 'T': return ParseTemplateParam();
+            case 'L': return ParseExpressionPrimary();
+            case 's':
+                if (*read_ptr++ == 'r') return ParseUnresolvedName();
+                --read_ptr;
+                // fallthrough
+            default:
+                return ParseExpressionPrimary();
+        }
+    }
+    
+    // <template-arg> ::= <type>                                             # type or template
+    //                ::= X <expression> E                                   # expression
+    //                ::= <expr-primary>                                     # simple expressions
+    //                ::= J <template-arg>* E                                # argument pack
+    //                ::= LZ <encoding> E                                    # extension
+    
+    bool ParseTemplateArg()
+    {
+        switch (*read_ptr) {
+            case 'J':
+#ifdef DEBUG_FAILURES
+                printf("*** Template argument packs unsupported\n");
+#endif
+                return false;
+            case 'X':
+                ++read_ptr;
+                if (!ParseExpression()) return false;
+                return Parse('E');
+            case 'L':
+                ++read_ptr;
+                return ParseExpressionPrimary();
+            default:
+                return ParseType();
+        }
+    }
+    
+    // <template-args> ::= I <template-arg>* E
+    //     extension, the abi says <template-arg>+
+    
+    bool ParseTemplateArgs(bool record_template_args = false)
+    {
+        if (record_template_args) ResetTemplateArgs();
+        
+        bool first_arg = true;
+        while (*read_ptr != 'E')
+        {
+            if (first_arg) first_arg = false;
+            else WriteCommaSpace();
+            
+            int template_start_cookie = GetStartCookie();
+            if (!ParseTemplateArg()) return false;
+            if (record_template_args) EndTemplateArg(template_start_cookie);
+        }
+        ++read_ptr;
+        return true;
+    }
+    
+    // <nested-name> ::= N [<CV-qualifiers>] [<ref-qualifier>] <prefix> <unqualified-name> E
+    //               ::= N [<CV-qualifiers>] [<ref-qualifier>] <template-prefix> <template-args> E
+    //
+    // <prefix> ::= <prefix> <unqualified-name>
+    //          ::= <template-prefix> <template-args>
+    //          ::= <template-param>
+    //          ::= <decltype>
+    //          ::= # empty
+    //          ::= <substitution>
+    //          ::= <prefix> <data-member-prefix>
+    //  extension ::= L
+    //
+    // <template-prefix> ::= <prefix> <template unqualified-name>
+    //                   ::= <template-param>
+    //                   ::= <substitution>
+    //
+    // <unqualified-name> ::= <operator-name>
+    //                    ::= <ctor-dtor-name>
+    //                    ::= <source-name>
+    //                    ::= <unnamed-type-name>
+    
+    bool ParseNestedName(NameState & name_state, bool parse_discriminator = false)
+    {
+        int qualifiers = TryParseQualifiers(true, true);
+        bool first_part = true;
+        bool suppress_substitution = true;
+        int name_start_cookie = GetStartCookie();
+        while (true)
+        {
+            char next = *read_ptr;
+            if (next == 'E')
+            {
+                ++read_ptr;
+                break;
+            }
+            
+            // Record a substitution candidate for all prefixes, but not the full name
+            if (suppress_substitution) suppress_substitution = false;
+            else EndSubstitution(name_start_cookie);
+            
+            if (next == 'I')
+            {
+                ++read_ptr;
+                name_state.is_last_generic = true;
+                WriteTemplateStart();
+                if (!ParseTemplateArgs(name_state.parse_function_params)) return false;
+                WriteTemplateEnd();
+                continue;
+            }
+            
+            if (first_part) first_part = false;
+            else WriteNamespaceSeparator();
+            
+            name_state.is_last_generic = false;
+            switch (next)
+            {
+                case '0':
+                case '1':
+                case '2':
+                case '3':
+                case '4':
+                case '5':
+                case '6':
+                case '7':
+                case '8':
+                case '9':
+                {
+                    int name_start_cookie = GetStartCookie();
+                    if (!ParseSourceName()) return false;
+                    name_state.last_name_range = EndRange(name_start_cookie);
+                    continue;
+                }
+                case 'S':
+                    if (*++read_ptr == 't')
+                    {
+                        WriteStdPrefix();
+                        ++read_ptr;
+                        if (!ParseUnqualifiedName(name_state)) return false;
+                    }
+                    else
+                    {
+                        if (!ParseSubstitution()) return false;
+                        suppress_substitution = true;
+                    }
+                    continue;
+                case 'T':
+                    ++read_ptr;
+                    if (!ParseTemplateParam()) return false;
+                    continue;
+                case 'C':
+                    ++read_ptr;
+                    if (!ParseCtor(name_state)) return false;
+                    continue;
+                case 'D':
+                {
+                    switch (*(read_ptr + 1))
+                    {
+                        case 't':
+                        case 'T':
+#ifdef DEBUG_FAILURES
+                            printf("*** Decltype unsupported\n");
+#endif
+                            return false;
+                    }
+                    ++read_ptr;
+                    if (!ParseDtor(name_state)) return false;
+                    continue;
+                }
+                case 'U':
+                    ++read_ptr;
+                    if (!ParseUnnamedTypeName(name_state)) return false;
+                    continue;
+                case 'L':
+                    ++read_ptr;
+                    if (!ParseUnqualifiedName(name_state)) return false;
+                    continue;
+                default:
+                    if (!ParseOperatorName(name_state)) return false;
+            }
+        }
+        
+        if (parse_discriminator) TryParseDiscriminator();
+        if (name_state.parse_function_params &&
+            !ParseFunctionArgs(name_state, name_start_cookie)) return false;
+        if (qualifiers) WriteQualifiers(qualifiers);
+        return true;
+    }
+    
+    // <local-name> := Z <function encoding> E <entity name> [<discriminator>]
+    //              := Z <function encoding> E s [<discriminator>]
+    //              := Z <function encoding> Ed [ <parameter number> ] _ <entity name>
+    
+    bool ParseLocalName(bool parse_function_params)
+    {
+        if (!ParseEncoding()) return false;
+        if (!Parse('E')) return false;
+        
+        switch (*read_ptr)
+        {
+            case 's':
+                TryParseDiscriminator(); // Optional and ignored
+                WRITE("::string literal");
+                break;
+            case 'd':
+                TryParseNumber(); // Optional and ignored
+                WriteNamespaceSeparator();
+                if (!ParseName()) return false;
+                break;
+            default:
+                WriteNamespaceSeparator();
+                if (!ParseName(parse_function_params, true)) return false;
+                TryParseDiscriminator(); // Optional and ignored
+        }
+        return true;
+    }
+    
+    // <name> ::= <nested-name>
+    //        ::= <local-name>
+    //        ::= <unscoped-template-name> <template-args>
+    //        ::= <unscoped-name>
+    
+    // <unscoped-template-name> ::= <unscoped-name>
+    //                          ::= <substitution>
+    
+    bool ParseName(bool parse_function_params = false,
+                   bool parse_discriminator = false)
+    {
+        NameState name_state = { parse_function_params };
+        int name_start_cookie = GetStartCookie();
+        
+        switch (*read_ptr)
+        {
+            case 'N':
+                ++read_ptr;
+                return ParseNestedName(name_state, parse_discriminator);
+            case 'Z':
+            {
+                ++read_ptr;
+                if (!ParseLocalName(parse_function_params)) return false;
+                break;
+            }
+            case 'L':
+                ++read_ptr;
+                // fallthrough
+            default:
+            {
+                if (!ParseUnscopedName(name_state)) return false;
+                
+                if (*read_ptr == 'I')
+                {
+                    EndSubstitution(name_start_cookie);
+                    
+                    ++read_ptr;
+                    name_state.is_last_generic = true;
+                    WriteTemplateStart();
+                    if (!ParseTemplateArgs(parse_function_params)) return false;
+                    WriteTemplateEnd();
+                }
+                break;
+            }
+        }
+        if (parse_discriminator) TryParseDiscriminator();
+        if (parse_function_params &&
+            !ParseFunctionArgs(name_state, name_start_cookie)) return false;
+        return true;
+    }
+    
+    // <call-offset> ::= h <nv-offset> _
+    //               ::= v <v-offset> _
+    //
+    // <nv-offset> ::= <offset number>
+    //                 # non-virtual base override
+    //
+    // <v-offset>  ::= <offset number> _ <virtual offset number>
+    //                 # virtual base override, with vcall offset
+    
+    bool ParseCallOffset()
+    {
+        switch (*read_ptr++)
+        {
+            case 'h':
+                if (*read_ptr == 'n') ++read_ptr;
+                if (TryParseNumber() == -1 || *read_ptr++ != '_') break;
+                return true;
+            case 'v':
+                if (*read_ptr == 'n') ++read_ptr;
+                if (TryParseNumber() == -1 || *read_ptr++ != '_') break;
+                if (*read_ptr == 'n') ++read_ptr;
+                if (TryParseNumber() == -1 || *read_ptr++ != '_') break;
+                return true;
+        }
+#ifdef DEBUG_FAILURES
+        printf("*** Malformed call offset\n");
+#endif
+        return false;
+    }
+    
+    // <special-name> ::= TV <type>    # virtual table
+    //                ::= TT <type>    # VTT structure (construction vtable index)
+    //                ::= TI <type>    # typeinfo structure
+    //                ::= TS <type>    # typeinfo name (null-terminated byte string)
+    //                ::= Tc <call-offset> <call-offset> <base encoding>
+    //                    # base is the nominal target function of thunk
+    //                    # first call-offset is 'this' adjustment
+    //                    # second call-offset is result adjustment
+    //                ::= T <call-offset> <base encoding>
+    //                    # base is the nominal target function of thunk
+    //      extension ::= TC <first type> <number> _ <second type> # construction vtable for second-in-first
+    
+    bool ParseSpecialNameT()
+    {
+        switch (*read_ptr++)
+        {
+            case 'V':
+                WRITE("vtable for ");
+                return ParseType();
+            case 'T':
+                WRITE("VTT for ");
+                return ParseType();
+            case 'I':
+                WRITE("typeinfo for ");
+                return ParseType();
+            case 'S':
+                WRITE("typeinfo name for ");
+                return ParseType();
+            case 'c':
+            case 'C':
+#ifdef DEBUG_FAILURES
+                printf("*** Unsupported thunk or construction vtable name: %.3s\n", read_ptr - 1);
+#endif
+                return false;
+            default:
+                if (*--read_ptr == 'v')
+                {
+                    WRITE("virtual thunk to ");
+                }
+                else
+                {
+                    WRITE("non-virtual thunk to ");
+                }
+                if (!ParseCallOffset()) return false;
+                return ParseEncoding();
+        }
+    }
+    
+    // <special-name> ::= GV <object name> # Guard variable for one-time initialization
+    //                                     # No <type>
+    //      extension ::= GR <object name> # reference temporary for object
+    
+    bool ParseSpecialNameG()
+    {
+        switch (*read_ptr++)
+        {
+            case 'V':
+                WRITE("guard variable for ");
+                if (!ParseName(true)) return false;
+                break;
+            case 'R':
+                WRITE("reference temporary for ");
+                if (!ParseName(true)) return false;
+                break;
+            default:
+#ifdef DEBUG_FAILURES
+                printf("*** Unknown G encoding\n");
+#endif
+                return false;
+        }
+        return true;
+    }
+    
+    // <bare-function-type> ::= <signature type>+        # types are possible return type, then parameter types
+    
+    bool ParseFunctionArgs(NameState & name_state, int return_insert_cookie)
+    {
+        char next = *read_ptr;
+        if (next == 'E' || next == '\0' || next == '.') return true;
+        
+        // Clang has a bad habit of making unique manglings by just sticking numbers on the end of a symbol,
+        // which is ambiguous with malformed source name manglings
+        const char * before_clang_uniquing_test = read_ptr;
+        if (TryParseNumber())
+        {
+            if (*read_ptr == '\0') return true;
+            read_ptr = before_clang_uniquing_test;
+        }
+        
+        if (name_state.is_last_generic && !name_state.has_no_return_type)
+        {
+            int return_type_start_cookie = GetStartCookie();
+            if (!ParseType()) return false;
+            Write(' ');
+            ReorderRange(EndRange(return_type_start_cookie),
+                         return_insert_cookie);
+        }
+        
+        Write('(');
+        bool first_param = true;
+        while (true)
+        {
+            switch (*read_ptr)
+            {
+                case '\0':
+                case 'E':
+                case '.':
+                    break;
+                case 'v':
+                    ++read_ptr;
+                    continue;
+                case '_':
+                    // Not a formal part of the mangling specification, but clang emits suffixes starting with _block_invoke
+                    if (strncmp(read_ptr, "_block_invoke", 13) == 0)
+                    {
+                        read_ptr += strlen(read_ptr);
+                        break;
+                    }
+                    // fallthrough
+                default:
+                    if (first_param) first_param = false;
+                    else WriteCommaSpace();
+                    
+                    if (!ParseType()) return false;
+                    continue;
+            }
+            break;
+        }
+        Write(')');
+        return true;
+    }
+    
+    // <encoding> ::= <function name> <bare-function-type>
+    //            ::= <data name>
+    //            ::= <special-name>
+    
+    bool ParseEncoding()
+    {
+        switch (*read_ptr)
+        {
+            case 'T':
+                ++read_ptr;
+                if (!ParseSpecialNameT()) return false;
+                break;
+            case 'G':
+                ++read_ptr;
+                if (!ParseSpecialNameG()) return false;
+                break;
+            default:
+                if (!ParseName(true)) return false;
+                break;
+        }
+        return true;
+    }
+    
+    bool ParseMangling(const char * mangled_name, long mangled_name_length = 0)
+    {
+        if (!mangled_name_length) mangled_name_length = strlen(mangled_name);
+        read_end = mangled_name + mangled_name_length;
+        read_ptr = mangled_name;
+        write_ptr = buffer;
+        next_substitute_index = 0;
+        next_template_arg_index = rewrite_ranges_size - 1;
+        
+        if (*read_ptr++ != '_' || *read_ptr++ != 'Z')
+        {
+#ifdef DEBUG_FAILURES
+            printf("*** Missing _Z prefix\n");
+#endif
+            return false;
+        }
+        if (!ParseEncoding()) return false;
+        switch (*read_ptr)
+        {
+            case '.':
+                Write(' ');
+                Write('(');
+                Write(read_ptr, read_end - read_ptr);
+                Write(')');
+            case '\0':
+                return true;
+            default:
+#ifdef DEBUG_FAILURES
+                printf("*** Unparsed mangled content\n");
+#endif
+                return false;
+        }
+    }
+    
+private:
+    
+    // External scratch storage used during demanglings
+    
+    char * buffer;
+    const char * buffer_end;
+    BufferRange * rewrite_ranges;
+    int rewrite_ranges_size;
+    bool owns_buffer;
+    bool owns_rewrite_ranges;
+    
+    // Internal state used during demangling
+    
+    const char * read_ptr;
+    const char * read_end;
+    char * write_ptr;
+    int next_template_arg_index;
+    int next_substitute_index;
+};
+
+} // Anonymous namespace
+
+// Public entry points referenced from Mangled.cpp
+namespace lldb_private
+{
+    char * FastDemangle(const char* mangled_name)
+    {
+        char buffer[16384];
+        SymbolDemangler demangler(buffer, sizeof(buffer));
+        return demangler.GetDemangledCopy(mangled_name);
+    }
+
+    char * FastDemangle(const char* mangled_name, long mangled_name_length)
+    {
+        char buffer[16384];
+        SymbolDemangler demangler(buffer, sizeof(buffer));
+        return demangler.GetDemangledCopy(mangled_name, mangled_name_length);
+    }
+} // lldb_private namespace
index 8df9fb8..b20013f 100644 (file)
 
 #ifdef LLDB_USE_BUILTIN_DEMANGLER
 
+// Provide a fast-path demangler implemented in FastDemangle.cpp until it can
+// replace the existing C++ demangler with a complete implementation
+namespace lldb_private
+{
+    extern char * FastDemangle (const char * mangled_name,
+                                long mangled_name_length);
+}
+
 //----------------------------------------------------------------------
 // Inlined copy of:
 // http://llvm.org/svn/llvm-project/libcxxabi/trunk/src/cxa_demangle.cpp
@@ -5129,7 +5137,6 @@ Mangled::SetValue (const ConstString &name)
     }
 }
 
-
 //----------------------------------------------------------------------
 // Generate the demangled name on demand using this accessor. Code in
 // this class will need to use this accessor if it wishes to decode
@@ -5151,6 +5158,7 @@ Mangled::GetDemangledName () const
 
         // Don't bother running anything that isn't mangled
         const char *mangled_cstr = m_mangled.GetCString();
+        long mangled_length = m_mangled.GetLength();
         if (cstring_is_mangled(mangled_cstr))
         {
             if (!m_mangled.GetMangledCounterpart(m_demangled))
@@ -5158,7 +5166,13 @@ Mangled::GetDemangledName () const
                 // We didn't already mangle this name, demangle it and if all goes well
                 // add it to our map.
 #ifdef LLDB_USE_BUILTIN_DEMANGLER
-                char *demangled_name = __cxa_demangle (mangled_cstr, NULL, NULL, NULL);
+                // Try to use the fast-path demangler first for the
+                // performance win, falling back to the full demangler only
+                // when necessary
+                char *demangled_name = FastDemangle (mangled_cstr,
+                                                     mangled_length);
+                if (!demangled_name)
+                    demangled_name = __cxa_demangle (mangled_cstr, NULL, NULL, NULL);
 #elif defined(_MSC_VER)
                 // Cannot demangle on msvc.
                 char *demangled_name = nullptr;