From 0e497d1554a915ace538dc08f03f1661aab8bdf7 Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Fri, 9 Aug 2019 22:31:59 +0000 Subject: [PATCH] cfi-icall: Allow the jump table to be optionally made non-canonical. The default behavior of Clang's indirect function call checker will replace the address of each CFI-checked function in the output file's symbol table with the address of a jump table entry which will pass CFI checks. We refer to this as making the jump table `canonical`. This property allows code that was not compiled with ``-fsanitize=cfi-icall`` to take a CFI-valid address of a function, but it comes with a couple of caveats that are especially relevant for users of cross-DSO CFI: - There is a performance and code size overhead associated with each exported function, because each such function must have an associated jump table entry, which must be emitted even in the common case where the function is never address-taken anywhere in the program, and must be used even for direct calls between DSOs, in addition to the PLT overhead. - There is no good way to take a CFI-valid address of a function written in assembly or a language not supported by Clang. The reason is that the code generator would need to insert a jump table in order to form a CFI-valid address for assembly functions, but there is no way in general for the code generator to determine the language of the function. This may be possible with LTO in the intra-DSO case, but in the cross-DSO case the only information available is the function declaration. One possible solution is to add a C wrapper for each assembly function, but these wrappers can present a significant maintenance burden for heavy users of assembly in addition to adding runtime overhead. For these reasons, we provide the option of making the jump table non-canonical with the flag ``-fno-sanitize-cfi-canonical-jump-tables``. When the jump table is made non-canonical, symbol table entries point directly to the function body. Any instances of a function's address being taken in C will be replaced with a jump table address. This scheme does have its own caveats, however. It does end up breaking function address equality more aggressively than the default behavior, especially in cross-DSO mode which normally preserves function address equality entirely. Furthermore, it is occasionally necessary for code not compiled with ``-fsanitize=cfi-icall`` to take a function address that is valid for CFI. For example, this is necessary when a function's address is taken by assembly code and then called by CFI-checking C code. The ``__attribute__((cfi_jump_table_canonical))`` attribute may be used to make the jump table entry of a specific function canonical so that the external code will end up taking a address for the function that will pass CFI checks. Fixes PR41972. Differential Revision: https://reviews.llvm.org/D65629 llvm-svn: 368495 --- clang/docs/ControlFlowIntegrity.rst | 48 +++++ clang/include/clang/Basic/Attr.td | 6 + clang/include/clang/Basic/AttrDocs.td | 12 ++ clang/include/clang/Basic/CodeGenOptions.def | 2 + clang/include/clang/Driver/Options.td | 7 + clang/include/clang/Driver/SanitizerArgs.h | 1 + clang/lib/CodeGen/CodeGenFunction.cpp | 3 + clang/lib/CodeGen/CodeGenModule.cpp | 36 ++-- clang/lib/Driver/SanitizerArgs.cpp | 7 + clang/lib/Frontend/CompilerInvocation.cpp | 2 + clang/lib/Sema/SemaDeclAttr.cpp | 3 + .../test/CodeGen/cfi-icall-canonical-jump-tables.c | 24 +++ clang/test/CodeGen/cfi-icall-cross-dso.c | 8 +- clang/test/Driver/fsanitize.c | 6 + ...pragma-attribute-supported-attributes-list.test | 1 + .../test/SemaCXX/attr-cfi-canonical-jump-table.cpp | 11 + llvm/include/llvm/Transforms/IPO/LowerTypeTests.h | 2 + llvm/lib/Transforms/IPO/CrossDSOCFI.cpp | 6 +- llvm/lib/Transforms/IPO/LowerTypeTests.cpp | 234 +++++++++++++-------- llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp | 5 +- .../test/Transforms/LowerTypeTests/import-icall.ll | 18 +- .../cfi-functions-canonical-jump-tables.ll | 23 ++ 22 files changed, 352 insertions(+), 113 deletions(-) create mode 100644 clang/test/CodeGen/cfi-icall-canonical-jump-tables.c create mode 100644 clang/test/SemaCXX/attr-cfi-canonical-jump-table.cpp create mode 100644 llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-functions-canonical-jump-tables.ll diff --git a/clang/docs/ControlFlowIntegrity.rst b/clang/docs/ControlFlowIntegrity.rst index f57bdf5..03e27d3 100644 --- a/clang/docs/ControlFlowIntegrity.rst +++ b/clang/docs/ControlFlowIntegrity.rst @@ -235,6 +235,54 @@ long as the qualifiers for the type they point to match. For example, ``char*``, ``-fsanitize-cfi-icall-generalize-pointers`` is not compatible with ``-fsanitize-cfi-cross-dso``. +.. _cfi-canonical-jump-tables: + +``-fsanitize-cfi-canonical-jump-tables`` +---------------------------------------- + +The default behavior of Clang's indirect function call checker will replace +the address of each CFI-checked function in the output file's symbol table +with the address of a jump table entry which will pass CFI checks. We refer +to this as making the jump table `canonical`. This property allows code that +was not compiled with ``-fsanitize=cfi-icall`` to take a CFI-valid address +of a function, but it comes with a couple of caveats that are especially +relevant for users of cross-DSO CFI: + +- There is a performance and code size overhead associated with each + exported function, because each such function must have an associated + jump table entry, which must be emitted even in the common case where the + function is never address-taken anywhere in the program, and must be used + even for direct calls between DSOs, in addition to the PLT overhead. + +- There is no good way to take a CFI-valid address of a function written in + assembly or a language not supported by Clang. The reason is that the code + generator would need to insert a jump table in order to form a CFI-valid + address for assembly functions, but there is no way in general for the + code generator to determine the language of the function. This may be + possible with LTO in the intra-DSO case, but in the cross-DSO case the only + information available is the function declaration. One possible solution + is to add a C wrapper for each assembly function, but these wrappers can + present a significant maintenance burden for heavy users of assembly in + addition to adding runtime overhead. + +For these reasons, we provide the option of making the jump table non-canonical +with the flag ``-fno-sanitize-cfi-canonical-jump-tables``. When the jump +table is made non-canonical, symbol table entries point directly to the +function body. Any instances of a function's address being taken in C will +be replaced with a jump table address. + +This scheme does have its own caveats, however. It does end up breaking +function address equality more aggressively than the default behavior, +especially in cross-DSO mode which normally preserves function address +equality entirely. + +Furthermore, it is occasionally necessary for code not compiled with +``-fsanitize=cfi-icall`` to take a function address that is valid +for CFI. For example, this is necessary when a function's address +is taken by assembly code and then called by CFI-checking C code. The +``__attribute__((cfi_canonical_jump_table))`` attribute may be used to make +the jump table entry of a specific function canonical so that the external +code will end up taking a address for the function that will pass CFI checks. ``-fsanitize=cfi-icall`` and ``-fsanitize=function`` ---------------------------------------------------- diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td index 9f9292d..db13e91 100644 --- a/clang/include/clang/Basic/Attr.td +++ b/clang/include/clang/Basic/Attr.td @@ -2436,6 +2436,12 @@ def NoSanitizeSpecific : InheritableAttr { let ASTNode = 0; } +def CFICanonicalJumpTable : InheritableAttr { + let Spellings = [Clang<"cfi_canonical_jump_table">]; + let Subjects = SubjectList<[Function], ErrorDiag>; + let Documentation = [CFICanonicalJumpTableDocs]; +} + // C/C++ Thread safety attributes (e.g. for deadlock, data race checking) // Not all of these attributes will be given a [[]] spelling. The attributes // which require access to function parameter names cannot use the [[]] spelling diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td index 0f10d90..1d6c1ab 100644 --- a/clang/include/clang/Basic/AttrDocs.td +++ b/clang/include/clang/Basic/AttrDocs.td @@ -2221,6 +2221,18 @@ to avoid false positives in other places. }]; } +def CFICanonicalJumpTableDocs : Documentation { + let Category = DocCatFunction; + let Heading = "cfi_canonical_jump_table"; + let Content = [{ +.. _langext-cfi_canonical_jump_table: + +Use ``__attribute__((cfi_canonical_jump_table))`` on a function declaration to +make the function's CFI jump table canonical. See :ref:`the CFI documentation +` for more details. + }]; +} + def DocCatTypeSafety : DocumentationCategory<"Type Safety Checking"> { let Content = [{ Clang supports additional attributes to enable checking type safety properties diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def index 400711e..736f201 100644 --- a/clang/include/clang/Basic/CodeGenOptions.def +++ b/clang/include/clang/Basic/CodeGenOptions.def @@ -195,6 +195,8 @@ CODEGENOPT(SanitizeMinimalRuntime, 1, 0) ///< Use "_minimal" sanitizer runtime f ///< diagnostics. CODEGENOPT(SanitizeCfiICallGeneralizePointers, 1, 0) ///< Generalize pointer types in ///< CFI icall function signatures +CODEGENOPT(SanitizeCfiCanonicalJumpTables, 1, 0) ///< Make jump table symbols canonical + ///< instead of creating a local jump table. CODEGENOPT(SanitizeCoverageType, 2, 0) ///< Type of sanitizer coverage ///< instrumentation. CODEGENOPT(SanitizeCoverageIndirectCalls, 1, 0) ///< Enable sanitizer coverage diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 19022b4..0f2c314 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -1061,6 +1061,13 @@ def fno_sanitize_cfi_cross_dso : Flag<["-"], "fno-sanitize-cfi-cross-dso">, def fsanitize_cfi_icall_generalize_pointers : Flag<["-"], "fsanitize-cfi-icall-generalize-pointers">, Group, HelpText<"Generalize pointers in CFI indirect call type signature checks">; +def fsanitize_cfi_canonical_jump_tables : Flag<["-"], "fsanitize-cfi-canonical-jump-tables">, + Group, + HelpText<"Make the jump table addresses canonical in the symbol table">; +def fno_sanitize_cfi_canonical_jump_tables : Flag<["-"], "fno-sanitize-cfi-canonical-jump-tables">, + Group, + Flags<[CoreOption, DriverOption]>, + HelpText<"Do not make the jump table addresses canonical in the symbol table">; def fsanitize_stats : Flag<["-"], "fsanitize-stats">, Group, HelpText<"Enable sanitizer statistics gathering.">; diff --git a/clang/include/clang/Driver/SanitizerArgs.h b/clang/include/clang/Driver/SanitizerArgs.h index e7de509..c37499e 100644 --- a/clang/include/clang/Driver/SanitizerArgs.h +++ b/clang/include/clang/Driver/SanitizerArgs.h @@ -32,6 +32,7 @@ class SanitizerArgs { bool MsanUseAfterDtor = true; bool CfiCrossDso = false; bool CfiICallGeneralizePointers = false; + bool CfiCanonicalJumpTables = false; int AsanFieldPadding = 0; bool SharedRuntime = false; bool AsanUseAfterScope = true; diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp index eafe266..f7d9c82 100644 --- a/clang/lib/CodeGen/CodeGenFunction.cpp +++ b/clang/lib/CodeGen/CodeGenFunction.cpp @@ -762,6 +762,9 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, if (CGM.getCodeGenOpts().ProfileSampleAccurate) Fn->addFnAttr("profile-sample-accurate"); + if (D && D->hasAttr()) + Fn->addFnAttr("cfi-canonical-jump-table"); + if (getLangOpts().OpenCL) { // Add metadata for a kernel function. if (const FunctionDecl *FD = dyn_cast_or_null(D)) diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index b650526..8943b40 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -535,6 +535,12 @@ void CodeGenModule::Release() { getModule().addModuleFlag(llvm::Module::Override, "Cross-DSO CFI", 1); } + if (LangOpts.Sanitize.has(SanitizerKind::CFIICall)) { + getModule().addModuleFlag(llvm::Module::Override, + "CFI Canonical Jump Tables", + CodeGenOpts.SanitizeCfiCanonicalJumpTables); + } + if (CodeGenOpts.CFProtectionReturn && Target.checkCFProtectionReturnSupported(getDiags())) { // Indicate that we want to instrument return control flow protection. @@ -1605,10 +1611,17 @@ void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D, F->setAlignment(2); } - // In the cross-dso CFI mode, we want !type attributes on definitions only. - if (CodeGenOpts.SanitizeCfiCrossDso) - if (auto *FD = dyn_cast(D)) - CreateFunctionTypeMetadataForIcall(FD, F); + // In the cross-dso CFI mode with canonical jump tables, we want !type + // attributes on definitions only. + if (CodeGenOpts.SanitizeCfiCrossDso && + CodeGenOpts.SanitizeCfiCanonicalJumpTables) { + if (auto *FD = dyn_cast(D)) { + // Skip available_externally functions. They won't be codegen'ed in the + // current module anyway. + if (getContext().GetGVALinkageForFunction(FD) != GVA_AvailableExternally) + CreateFunctionTypeMetadataForIcall(FD, F); + } + } // Emit type metadata on member functions for member function pointer checks. // These are only ever necessary on definitions; we're guaranteed that the @@ -1765,14 +1778,6 @@ void CodeGenModule::CreateFunctionTypeMetadataForIcall(const FunctionDecl *FD, if (isa(FD) && !cast(FD)->isStatic()) return; - // Additionally, if building with cross-DSO support... - if (CodeGenOpts.SanitizeCfiCrossDso) { - // Skip available_externally functions. They won't be codegen'ed in the - // current module anyway. - if (getContext().GetGVALinkageForFunction(FD) == GVA_AvailableExternally) - return; - } - llvm::Metadata *MD = CreateMetadataIdentifierForType(FD->getType()); F->addTypeMetadata(0, MD); F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(FD->getType())); @@ -1849,8 +1854,11 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F, F->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); // Don't emit entries for function declarations in the cross-DSO mode. This - // is handled with better precision by the receiving DSO. - if (!CodeGenOpts.SanitizeCfiCrossDso) + // is handled with better precision by the receiving DSO. But if jump tables + // are non-canonical then we need type metadata in order to produce the local + // jump table. + if (!CodeGenOpts.SanitizeCfiCrossDso || + !CodeGenOpts.SanitizeCfiCanonicalJumpTables) CreateFunctionTypeMetadataForIcall(FD, F); if (getLangOpts().OpenMP && FD->hasAttr()) diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp index 8e59e19..7d4cc53 100644 --- a/clang/lib/Driver/SanitizerArgs.cpp +++ b/clang/lib/Driver/SanitizerArgs.cpp @@ -636,6 +636,10 @@ SanitizerArgs::SanitizerArgs(const ToolChain &TC, D.Diag(diag::err_drv_argument_not_allowed_with) << "-fsanitize-cfi-cross-dso" << "-fsanitize-cfi-icall-generalize-pointers"; + + CfiCanonicalJumpTables = + Args.hasFlag(options::OPT_fsanitize_cfi_canonical_jump_tables, + options::OPT_fno_sanitize_cfi_canonical_jump_tables, true); } Stats = Args.hasFlag(options::OPT_fsanitize_stats, @@ -976,6 +980,9 @@ void SanitizerArgs::addArgs(const ToolChain &TC, const llvm::opt::ArgList &Args, if (CfiICallGeneralizePointers) CmdArgs.push_back("-fsanitize-cfi-icall-generalize-pointers"); + if (CfiCanonicalJumpTables) + CmdArgs.push_back("-fsanitize-cfi-canonical-jump-tables"); + if (Stats) CmdArgs.push_back("-fsanitize-stats"); diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp index 7d1b196..fb5f1cc 100644 --- a/clang/lib/Frontend/CompilerInvocation.cpp +++ b/clang/lib/Frontend/CompilerInvocation.cpp @@ -1139,6 +1139,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK, Opts.SanitizeCfiCrossDso = Args.hasArg(OPT_fsanitize_cfi_cross_dso); Opts.SanitizeCfiICallGeneralizePointers = Args.hasArg(OPT_fsanitize_cfi_icall_generalize_pointers); + Opts.SanitizeCfiCanonicalJumpTables = + Args.hasArg(OPT_fsanitize_cfi_canonical_jump_tables); Opts.SanitizeStats = Args.hasArg(OPT_fsanitize_stats); if (Arg *A = Args.getLastArg( OPT_fsanitize_address_poison_custom_array_cookie, diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp index 950dcac..2a72f7d 100644 --- a/clang/lib/Sema/SemaDeclAttr.cpp +++ b/clang/lib/Sema/SemaDeclAttr.cpp @@ -7198,6 +7198,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, // Interacts with -fstack-protector options. handleSimpleAttribute(S, D, AL); break; + case ParsedAttr::AT_CFICanonicalJumpTable: + handleSimpleAttribute(S, D, AL); + break; case ParsedAttr::AT_StdCall: case ParsedAttr::AT_CDecl: case ParsedAttr::AT_FastCall: diff --git a/clang/test/CodeGen/cfi-icall-canonical-jump-tables.c b/clang/test/CodeGen/cfi-icall-canonical-jump-tables.c new file mode 100644 index 0000000..cf7ca42 --- /dev/null +++ b/clang/test/CodeGen/cfi-icall-canonical-jump-tables.c @@ -0,0 +1,24 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-icall -fsanitize-cfi-cross-dso -emit-llvm -o - %s | FileCheck --check-prefixes=CHECK,NOCANON %s +// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-icall -fsanitize-cfi-cross-dso -fsanitize-cfi-canonical-jump-tables -emit-llvm -o - %s | FileCheck --check-prefixes=CHECK,CANON %s + +void ext(void); + +// CHECK: define void @f({{.*}} [[ATTR1:#[0-9]+]] +void f() { + ext(); +} + +// NOCANON: declare !type {{.*}} @ext() +// CANON: declare void @ext() + +// CHECK: define void @g({{.*}} [[ATTR2:#[0-9]+]] +__attribute__((cfi_canonical_jump_table)) void g() {} + +// CHECK: [[ATTR1]] = { +// CHECK-NOT: "cfi-canonical-jump-table" +// CHECK: } + +// CHECK: [[ATTR2]] = { {{.*}} "cfi-canonical-jump-table" {{.*}} } + +// NOCANON: !{i32 4, !"CFI Canonical Jump Tables", i32 0} +// CANON: !{i32 4, !"CFI Canonical Jump Tables", i32 1} diff --git a/clang/test/CodeGen/cfi-icall-cross-dso.c b/clang/test/CodeGen/cfi-icall-cross-dso.c index 67901c4..fbfe213 100644 --- a/clang/test/CodeGen/cfi-icall-cross-dso.c +++ b/clang/test/CodeGen/cfi-icall-cross-dso.c @@ -1,27 +1,27 @@ // RUN: %clang_cc1 -triple x86_64-unknown-linux -O1 -fno-experimental-new-pass-manager \ // RUN: -fsanitize=cfi-icall -fsanitize-cfi-cross-dso \ -// RUN: -emit-llvm -o - %s | FileCheck \ +// RUN: -fsanitize-cfi-canonical-jump-tables -emit-llvm -o - %s | FileCheck \ // RUN: --check-prefix=CHECK --check-prefix=CHECK-DIAG \ // RUN: --check-prefix=ITANIUM --check-prefix=ITANIUM-DIAG \ // RUN: %s // RUN: %clang_cc1 -triple x86_64-unknown-linux -O1 -fno-experimental-new-pass-manager \ // RUN: -fsanitize=cfi-icall -fsanitize-cfi-cross-dso -fsanitize-trap=cfi-icall \ -// RUN: -emit-llvm -o - %s | FileCheck \ +// RUN: -fsanitize-cfi-canonical-jump-tables -emit-llvm -o - %s | FileCheck \ // RUN: --check-prefix=CHECK \ // RUN: --check-prefix=ITANIUM --check-prefix=ITANIUM-TRAP \ // RUN: %s // RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -O1 -fno-experimental-new-pass-manager \ // RUN: -fsanitize=cfi-icall -fsanitize-cfi-cross-dso \ -// RUN: -emit-llvm -o - %s | FileCheck \ +// RUN: -fsanitize-cfi-canonical-jump-tables -emit-llvm -o - %s | FileCheck \ // RUN: --check-prefix=CHECK --check-prefix=CHECK-DIAG \ // RUN: --check-prefix=MS --check-prefix=MS-DIAG \ // RUN: %s // RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -O1 -fno-experimental-new-pass-manager \ // RUN: -fsanitize=cfi-icall -fsanitize-cfi-cross-dso -fsanitize-trap=cfi-icall \ -// RUN: -emit-llvm -o - %s | FileCheck \ +// RUN: -fsanitize-cfi-canonical-jump-tables -emit-llvm -o - %s | FileCheck \ // RUN: --check-prefix=CHECK \ // RUN: --check-prefix=MS --check-prefix=MS-TRAP \ // RUN: %s diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c index 0caac04..6e8e61b 100644 --- a/clang/test/Driver/fsanitize.c +++ b/clang/test/Driver/fsanitize.c @@ -621,6 +621,12 @@ // RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-icall -fsanitize-cfi-icall-generalize-pointers -fsanitize-cfi-cross-dso -fvisibility=hidden -flto -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-GENERALIZE-AND-CROSS-DSO // CHECK-CFI-GENERALIZE-AND-CROSS-DSO: error: invalid argument '-fsanitize-cfi-cross-dso' not allowed with '-fsanitize-cfi-icall-generalize-pointers' +// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-icall -fsanitize-cfi-canonical-jump-tables -fvisibility=hidden -flto -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-CANONICAL-JUMP-TABLES +// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-icall -fno-sanitize-cfi-canonical-jump-tables -fvisibility=hidden -flto -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-NO-CFI-CANONICAL-JUMP-TABLES +// RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi-icall -fvisibility=hidden -flto -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-CANONICAL-JUMP-TABLES +// CHECK-CFI-CANONICAL-JUMP-TABLES: -fsanitize-cfi-canonical-jump-tables +// CHECK-NO-CFI-CANONICAL-JUMP-TABLES-NOT: -fsanitize-cfi-canonical-jump-tables + // RUN: %clang -target x86_64-linux-gnu -fsanitize=cfi -fsanitize-stats -flto -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CFI-STATS // CHECK-CFI-STATS: -fsanitize-stats diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test index cc2d380..83b8b9f 100644 --- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test +++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test @@ -21,6 +21,7 @@ // CHECK-NEXT: Availability ((SubjectMatchRule_record, SubjectMatchRule_enum, SubjectMatchRule_enum_constant, SubjectMatchRule_field, SubjectMatchRule_function, SubjectMatchRule_namespace, SubjectMatchRule_objc_category, SubjectMatchRule_objc_implementation, SubjectMatchRule_objc_interface, SubjectMatchRule_objc_method, SubjectMatchRule_objc_property, SubjectMatchRule_objc_protocol, SubjectMatchRule_record, SubjectMatchRule_type_alias, SubjectMatchRule_variable)) // CHECK-NEXT: CFAuditedTransfer (SubjectMatchRule_function) // CHECK-NEXT: CFConsumed (SubjectMatchRule_variable_is_parameter) +// CHECK-NEXT: CFICanonicalJumpTable (SubjectMatchRule_function) // CHECK-NEXT: CFUnknownTransfer (SubjectMatchRule_function) // CHECK-NEXT: CPUDispatch (SubjectMatchRule_function) // CHECK-NEXT: CPUSpecific (SubjectMatchRule_function) diff --git a/clang/test/SemaCXX/attr-cfi-canonical-jump-table.cpp b/clang/test/SemaCXX/attr-cfi-canonical-jump-table.cpp new file mode 100644 index 0000000..a53fbae --- /dev/null +++ b/clang/test/SemaCXX/attr-cfi-canonical-jump-table.cpp @@ -0,0 +1,11 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsyntax-only -verify %s + +__attribute__((cfi_canonical_jump_table)) void fdecl(); + +__attribute__((cfi_canonical_jump_table)) void f() {} + +struct S { + __attribute__((cfi_canonical_jump_table)) void f() {} +}; + +__attribute__((cfi_canonical_jump_table)) int i; // expected-error {{'cfi_canonical_jump_table' attribute only applies to functions}} diff --git a/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h b/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h index 39b23f5..3c2bb65 100644 --- a/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h +++ b/llvm/include/llvm/Transforms/IPO/LowerTypeTests.h @@ -193,6 +193,8 @@ struct ByteArrayBuilder { uint64_t &AllocByteOffset, uint8_t &AllocMask); }; +bool isJumpTableCanonical(Function *F); + } // end namespace lowertypetests class LowerTypeTestsPass : public PassInfoMixin { diff --git a/llvm/lib/Transforms/IPO/CrossDSOCFI.cpp b/llvm/lib/Transforms/IPO/CrossDSOCFI.cpp index e30b33a..8b2842e 100644 --- a/llvm/lib/Transforms/IPO/CrossDSOCFI.cpp +++ b/llvm/lib/Transforms/IPO/CrossDSOCFI.cpp @@ -84,13 +84,9 @@ void CrossDSOCFI::buildCFICheck(Module &M) { for (GlobalObject &GO : M.global_objects()) { Types.clear(); GO.getMetadata(LLVMContext::MD_type, Types); - for (MDNode *Type : Types) { - // Sanity check. GO must not be a function declaration. - assert(!isa(&GO) || !cast(&GO)->isDeclaration()); - + for (MDNode *Type : Types) if (ConstantInt *TypeId = extractNumericTypeId(Type)) TypeIds.insert(TypeId->getZExtValue()); - } } NamedMDNode *CfiFunctionsMD = M.getNamedMetadata("cfi.functions"); diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp index fd1b0cd..1b83ccb 100644 --- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp +++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp @@ -230,6 +230,16 @@ void ByteArrayBuilder::allocate(const std::set &Bits, Bytes[AllocByteOffset + B] |= AllocMask; } +bool lowertypetests::isJumpTableCanonical(Function *F) { + if (F->isDeclarationForLinker()) + return false; + auto *CI = mdconst::extract_or_null( + F->getParent()->getModuleFlag("CFI Canonical Jump Tables")); + if (!CI || CI->getZExtValue() != 0) + return true; + return F->hasFnAttribute("cfi-canonical-jump-table"); +} + namespace { struct ByteArrayInfo { @@ -251,9 +261,12 @@ class GlobalTypeMember final : TrailingObjects { GlobalObject *GO; size_t NTypes; - // For functions: true if this is a definition (either in the merged module or - // in one of the thinlto modules). - bool IsDefinition; + // For functions: true if the jump table is canonical. This essentially means + // whether the canonical address (i.e. the symbol table entry) of the function + // is provided by the local jump table. This is normally the same as whether + // the function is defined locally, but if canonical jump tables are disabled + // by the user then the jump table never provides a canonical definition. + bool IsJumpTableCanonical; // For functions: true if this function is either defined or used in a thinlto // module and its jumptable entry needs to be exported to thinlto backends. @@ -263,13 +276,13 @@ class GlobalTypeMember final : TrailingObjects { public: static GlobalTypeMember *create(BumpPtrAllocator &Alloc, GlobalObject *GO, - bool IsDefinition, bool IsExported, + bool IsJumpTableCanonical, bool IsExported, ArrayRef Types) { auto *GTM = static_cast(Alloc.Allocate( totalSizeToAlloc(Types.size()), alignof(GlobalTypeMember))); GTM->GO = GO; GTM->NTypes = Types.size(); - GTM->IsDefinition = IsDefinition; + GTM->IsJumpTableCanonical = IsJumpTableCanonical; GTM->IsExported = IsExported; std::uninitialized_copy(Types.begin(), Types.end(), GTM->getTrailingObjects()); @@ -280,8 +293,8 @@ public: return GO; } - bool isDefinition() const { - return IsDefinition; + bool isJumpTableCanonical() const { + return IsJumpTableCanonical; } bool isExported() const { @@ -320,6 +333,49 @@ private: size_t NTargets; }; +struct ScopedSaveAliaseesAndUsed { + Module &M; + SmallPtrSet Used, CompilerUsed; + std::vector> FunctionAliases; + + ScopedSaveAliaseesAndUsed(Module &M) : M(M) { + // The users of this class want to replace all function references except + // for aliases and llvm.used/llvm.compiler.used with references to a jump + // table. We avoid replacing aliases in order to avoid introducing a double + // indirection (or an alias pointing to a declaration in ThinLTO mode), and + // we avoid replacing llvm.used/llvm.compiler.used because these global + // variables describe properties of the global, not the jump table (besides, + // offseted references to the jump table in llvm.used are invalid). + // Unfortunately, LLVM doesn't have a "RAUW except for these (possibly + // indirect) users", so what we do is save the list of globals referenced by + // llvm.used/llvm.compiler.used and aliases, erase the used lists, let RAUW + // replace the aliasees and then set them back to their original values at + // the end. + if (GlobalVariable *GV = collectUsedGlobalVariables(M, Used, false)) + GV->eraseFromParent(); + if (GlobalVariable *GV = collectUsedGlobalVariables(M, CompilerUsed, true)) + GV->eraseFromParent(); + + for (auto &GIS : concat(M.aliases(), M.ifuncs())) { + // FIXME: This should look past all aliases not just interposable ones, + // see discussion on D65118. + if (auto *F = + dyn_cast(GIS.getIndirectSymbol()->stripPointerCasts())) + FunctionAliases.push_back({&GIS, F}); + } + } + + ~ScopedSaveAliaseesAndUsed() { + appendToUsed(M, std::vector(Used.begin(), Used.end())); + appendToCompilerUsed(M, std::vector(CompilerUsed.begin(), + CompilerUsed.end())); + + for (auto P : FunctionAliases) + P.first->setIndirectSymbol( + ConstantExpr::getBitCast(P.second, P.first->getType())); + } +}; + class LowerTypeTestsModule { Module &M; @@ -387,7 +443,8 @@ class LowerTypeTestsModule { uint8_t *exportTypeId(StringRef TypeId, const TypeIdLowering &TIL); TypeIdLowering importTypeId(StringRef TypeId); void importTypeTest(CallInst *CI); - void importFunction(Function *F, bool isDefinition); + void importFunction(Function *F, bool isJumpTableCanonical, + std::vector &AliasesToErase); BitSetInfo buildBitSet(Metadata *TypeId, @@ -421,7 +478,8 @@ class LowerTypeTestsModule { ArrayRef Globals, ArrayRef ICallBranchFunnels); - void replaceWeakDeclarationWithJumpTablePtr(Function *F, Constant *JT, bool IsDefinition); + void replaceWeakDeclarationWithJumpTablePtr(Function *F, Constant *JT, + bool IsJumpTableCanonical); void moveInitializerToModuleConstructor(GlobalVariable *GV); void findGlobalVariableUsersOf(Constant *C, SmallSetVector &Out); @@ -433,7 +491,7 @@ class LowerTypeTestsModule { /// the block. 'This's use list is expected to have at least one element. /// Unlike replaceAllUsesWith this function skips blockaddr and direct call /// uses. - void replaceCfiUses(Function *Old, Value *New, bool IsDefinition); + void replaceCfiUses(Function *Old, Value *New, bool IsJumpTableCanonical); /// replaceDirectCalls - Go through the uses list for this definition and /// replace each use, which is a direct function call. @@ -982,14 +1040,16 @@ void LowerTypeTestsModule::importTypeTest(CallInst *CI) { } // ThinLTO backend: the function F has a jump table entry; update this module -// accordingly. isDefinition describes the type of the jump table entry. -void LowerTypeTestsModule::importFunction(Function *F, bool isDefinition) { +// accordingly. isJumpTableCanonical describes the type of the jump table entry. +void LowerTypeTestsModule::importFunction( + Function *F, bool isJumpTableCanonical, + std::vector &AliasesToErase) { assert(F->getType()->getAddressSpace() == 0); GlobalValue::VisibilityTypes Visibility = F->getVisibility(); std::string Name = F->getName(); - if (F->isDeclarationForLinker() && isDefinition) { + if (F->isDeclarationForLinker() && isJumpTableCanonical) { // Non-dso_local functions may be overriden at run time, // don't short curcuit them if (F->isDSOLocal()) { @@ -1004,12 +1064,13 @@ void LowerTypeTestsModule::importFunction(Function *F, bool isDefinition) { } Function *FDecl; - if (F->isDeclarationForLinker() && !isDefinition) { - // Declaration of an external function. + if (!isJumpTableCanonical) { + // Either a declaration of an external function or a reference to a locally + // defined jump table. FDecl = Function::Create(F->getFunctionType(), GlobalValue::ExternalLinkage, F->getAddressSpace(), Name + ".cfi_jt", &M); FDecl->setVisibility(GlobalValue::HiddenVisibility); - } else if (isDefinition) { + } else { F->setName(Name + ".cfi"); F->setLinkage(GlobalValue::ExternalLinkage); FDecl = Function::Create(F->getFunctionType(), GlobalValue::ExternalLinkage, @@ -1018,8 +1079,8 @@ void LowerTypeTestsModule::importFunction(Function *F, bool isDefinition) { Visibility = GlobalValue::HiddenVisibility; // Delete aliases pointing to this function, they'll be re-created in the - // merged output - SmallVector ToErase; + // merged output. Don't do it yet though because ScopedSaveAliaseesAndUsed + // will want to reset the aliasees first. for (auto &U : F->uses()) { if (auto *A = dyn_cast(U.getUser())) { Function *AliasDecl = Function::Create( @@ -1027,24 +1088,15 @@ void LowerTypeTestsModule::importFunction(Function *F, bool isDefinition) { F->getAddressSpace(), "", &M); AliasDecl->takeName(A); A->replaceAllUsesWith(AliasDecl); - ToErase.push_back(A); + AliasesToErase.push_back(A); } } - for (auto *A : ToErase) - A->eraseFromParent(); - } else { - // Function definition without type metadata, where some other translation - // unit contained a declaration with type metadata. This normally happens - // during mixed CFI + non-CFI compilation. We do nothing with the function - // so that it is treated the same way as a function defined outside of the - // LTO unit. - return; } - if (F->isWeakForLinker()) - replaceWeakDeclarationWithJumpTablePtr(F, FDecl, isDefinition); + if (F->hasExternalWeakLinkage()) + replaceWeakDeclarationWithJumpTablePtr(F, FDecl, isJumpTableCanonical); else - replaceCfiUses(F, FDecl, isDefinition); + replaceCfiUses(F, FDecl, isJumpTableCanonical); // Set visibility late because it's used in replaceCfiUses() to determine // whether uses need to to be replaced. @@ -1232,7 +1284,7 @@ void LowerTypeTestsModule::findGlobalVariableUsersOf( // Replace all uses of F with (F ? JT : 0). void LowerTypeTestsModule::replaceWeakDeclarationWithJumpTablePtr( - Function *F, Constant *JT, bool IsDefinition) { + Function *F, Constant *JT, bool IsJumpTableCanonical) { // The target expression can not appear in a constant initializer on most // (all?) targets. Switch to a runtime initializer. SmallSetVector GlobalVarUsers; @@ -1246,7 +1298,7 @@ void LowerTypeTestsModule::replaceWeakDeclarationWithJumpTablePtr( Function::Create(cast(F->getValueType()), GlobalValue::ExternalWeakLinkage, F->getAddressSpace(), "", &M); - replaceCfiUses(F, PlaceholderFn, IsDefinition); + replaceCfiUses(F, PlaceholderFn, IsJumpTableCanonical); Constant *Target = ConstantExpr::getSelect( ConstantExpr::getICmp(CmpInst::ICMP_NE, F, @@ -1283,8 +1335,9 @@ selectJumpTableArmEncoding(ArrayRef Functions, unsigned ArmCount = 0, ThumbCount = 0; for (const auto GTM : Functions) { - if (!GTM->isDefinition()) { + if (!GTM->isJumpTableCanonical()) { // PLT stubs are always ARM. + // FIXME: This is the wrong heuristic for non-canonical jump tables. ++ArmCount; continue; } @@ -1445,47 +1498,53 @@ void LowerTypeTestsModule::buildBitSetsFromFunctionsNative( lowerTypeTestCalls(TypeIds, JumpTable, GlobalLayout); - // Build aliases pointing to offsets into the jump table, and replace - // references to the original functions with references to the aliases. - for (unsigned I = 0; I != Functions.size(); ++I) { - Function *F = cast(Functions[I]->getGlobal()); - bool IsDefinition = Functions[I]->isDefinition(); - - Constant *CombinedGlobalElemPtr = ConstantExpr::getBitCast( - ConstantExpr::getInBoundsGetElementPtr( - JumpTableType, JumpTable, - ArrayRef{ConstantInt::get(IntPtrTy, 0), - ConstantInt::get(IntPtrTy, I)}), - F->getType()); - if (Functions[I]->isExported()) { - if (IsDefinition) { - ExportSummary->cfiFunctionDefs().insert(F->getName()); + { + ScopedSaveAliaseesAndUsed S(M); + + // Build aliases pointing to offsets into the jump table, and replace + // references to the original functions with references to the aliases. + for (unsigned I = 0; I != Functions.size(); ++I) { + Function *F = cast(Functions[I]->getGlobal()); + bool IsJumpTableCanonical = Functions[I]->isJumpTableCanonical(); + + Constant *CombinedGlobalElemPtr = ConstantExpr::getBitCast( + ConstantExpr::getInBoundsGetElementPtr( + JumpTableType, JumpTable, + ArrayRef{ConstantInt::get(IntPtrTy, 0), + ConstantInt::get(IntPtrTy, I)}), + F->getType()); + if (Functions[I]->isExported()) { + if (IsJumpTableCanonical) { + ExportSummary->cfiFunctionDefs().insert(F->getName()); + } else { + GlobalAlias *JtAlias = GlobalAlias::create( + F->getValueType(), 0, GlobalValue::ExternalLinkage, + F->getName() + ".cfi_jt", CombinedGlobalElemPtr, &M); + JtAlias->setVisibility(GlobalValue::HiddenVisibility); + ExportSummary->cfiFunctionDecls().insert(F->getName()); + } + } + if (!IsJumpTableCanonical) { + if (F->hasExternalWeakLinkage()) + replaceWeakDeclarationWithJumpTablePtr(F, CombinedGlobalElemPtr, + IsJumpTableCanonical); + else + replaceCfiUses(F, CombinedGlobalElemPtr, IsJumpTableCanonical); } else { - GlobalAlias *JtAlias = GlobalAlias::create( - F->getValueType(), 0, GlobalValue::ExternalLinkage, - F->getName() + ".cfi_jt", CombinedGlobalElemPtr, &M); - JtAlias->setVisibility(GlobalValue::HiddenVisibility); - ExportSummary->cfiFunctionDecls().insert(F->getName()); + assert(F->getType()->getAddressSpace() == 0); + + GlobalAlias *FAlias = + GlobalAlias::create(F->getValueType(), 0, F->getLinkage(), "", + CombinedGlobalElemPtr, &M); + FAlias->setVisibility(F->getVisibility()); + FAlias->takeName(F); + if (FAlias->hasName()) + F->setName(FAlias->getName() + ".cfi"); + replaceCfiUses(F, FAlias, IsJumpTableCanonical); + if (!F->hasLocalLinkage()) + F->setVisibility(GlobalVariable::HiddenVisibility); } } - if (!IsDefinition) { - if (F->isWeakForLinker()) - replaceWeakDeclarationWithJumpTablePtr(F, CombinedGlobalElemPtr, IsDefinition); - else - replaceCfiUses(F, CombinedGlobalElemPtr, IsDefinition); - } else { - assert(F->getType()->getAddressSpace() == 0); - - GlobalAlias *FAlias = GlobalAlias::create( - F->getValueType(), 0, F->getLinkage(), "", CombinedGlobalElemPtr, &M); - FAlias->setVisibility(F->getVisibility()); - FAlias->takeName(F); - if (FAlias->hasName()) - F->setName(FAlias->getName() + ".cfi"); - replaceCfiUses(F, FAlias, IsDefinition); - if (!F->hasLocalLinkage()) - F->setVisibility(GlobalVariable::HiddenVisibility); - } } createJumpTable(JumpTableFn, Functions); @@ -1650,7 +1709,8 @@ static bool isDirectCall(Use& U) { return false; } -void LowerTypeTestsModule::replaceCfiUses(Function *Old, Value *New, bool IsDefinition) { +void LowerTypeTestsModule::replaceCfiUses(Function *Old, Value *New, + bool IsJumpTableCanonical) { SmallSetVector Constants; auto UI = Old->use_begin(), E = Old->use_end(); for (; UI != E;) { @@ -1662,7 +1722,7 @@ void LowerTypeTestsModule::replaceCfiUses(Function *Old, Value *New, bool IsDefi continue; // Skip direct calls to externally defined or non-dso_local functions - if (isDirectCall(U) && (Old->isDSOLocal() || !IsDefinition)) + if (isDirectCall(U) && (Old->isDSOLocal() || !IsJumpTableCanonical)) continue; // Must handle Constants specially, we cannot call replaceUsesOfWith on a @@ -1732,10 +1792,16 @@ bool LowerTypeTestsModule::lower() { Decls.push_back(&F); } - for (auto F : Defs) - importFunction(F, /*isDefinition*/ true); - for (auto F : Decls) - importFunction(F, /*isDefinition*/ false); + std::vector AliasesToErase; + { + ScopedSaveAliaseesAndUsed S(M); + for (auto F : Defs) + importFunction(F, /*isJumpTableCanonical*/ true, AliasesToErase); + for (auto F : Decls) + importFunction(F, /*isJumpTableCanonical*/ false, AliasesToErase); + } + for (GlobalAlias *GA : AliasesToErase) + GA->eraseFromParent(); return true; } @@ -1869,24 +1935,26 @@ bool LowerTypeTestsModule::lower() { Types.clear(); GO.getMetadata(LLVMContext::MD_type, Types); - bool IsDefinition = !GO.isDeclarationForLinker(); + bool IsJumpTableCanonical = false; bool IsExported = false; if (Function *F = dyn_cast(&GO)) { + IsJumpTableCanonical = isJumpTableCanonical(F); if (ExportedFunctions.count(F->getName())) { - IsDefinition |= ExportedFunctions[F->getName()].Linkage == CFL_Definition; + IsJumpTableCanonical |= + ExportedFunctions[F->getName()].Linkage == CFL_Definition; IsExported = true; // TODO: The logic here checks only that the function is address taken, // not that the address takers are live. This can be updated to check // their liveness and emit fewer jumptable entries once monolithic LTO // builds also emit summaries. } else if (!F->hasAddressTaken()) { - if (!CrossDsoCfi || !IsDefinition || F->hasLocalLinkage()) + if (!CrossDsoCfi || !IsJumpTableCanonical || F->hasLocalLinkage()) continue; } } - auto *GTM = - GlobalTypeMember::create(Alloc, &GO, IsDefinition, IsExported, Types); + auto *GTM = GlobalTypeMember::create(Alloc, &GO, IsJumpTableCanonical, + IsExported, Types); GlobalTypeMembers[&GO] = GTM; for (MDNode *Type : Types) { verifyTypeMDNode(&GO, Type); diff --git a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp index f0dea11..31c731e7 100644 --- a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp +++ b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp @@ -24,6 +24,7 @@ #include "llvm/Transforms/IPO.h" #include "llvm/Transforms/IPO/FunctionAttrs.h" #include "llvm/Transforms/IPO/FunctionImport.h" +#include "llvm/Transforms/IPO/LowerTypeTests.h" #include "llvm/Transforms/Utils/Cloning.h" #include "llvm/Transforms/Utils/ModuleUtils.h" using namespace llvm; @@ -323,9 +324,9 @@ void splitAndWriteThinLTOBitcode( SmallVector Elts; Elts.push_back(MDString::get(Ctx, F.getName())); CfiFunctionLinkage Linkage; - if (!F.isDeclarationForLinker()) + if (lowertypetests::isJumpTableCanonical(&F)) Linkage = CFL_Definition; - else if (F.isWeakForLinker()) + else if (F.hasExternalWeakLinkage()) Linkage = CFL_WeakDeclaration; else Linkage = CFL_Declaration; diff --git a/llvm/test/Transforms/LowerTypeTests/import-icall.ll b/llvm/test/Transforms/LowerTypeTests/import-icall.ll index 0b151db..67788a2 100644 --- a/llvm/test/Transforms/LowerTypeTests/import-icall.ll +++ b/llvm/test/Transforms/LowerTypeTests/import-icall.ll @@ -3,6 +3,11 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" +@llvm.used = appending global [1 x i8*] [i8* bitcast (i8* ()* @local_decl to i8*)], section "llvm.metadata" +@llvm.compiler.used = appending global [1 x i8*] [i8* bitcast (i8* ()* @local_decl to i8*)], section "llvm.metadata" + +@local_decl_alias = alias i8* (), i8* ()* @local_decl + define i8 @local_a() { call void @external() call void @external_weak() @@ -19,14 +24,16 @@ define i8 @use_b() { ret i8 %x } -define void @local_decl() { - call void @local_decl() - ret void +define i8* @local_decl() { + call i8* @local_decl() + ret i8* bitcast (i8* ()* @local_decl to i8*) } declare void @external() declare extern_weak void @external_weak() +; CHECK: @local_decl_alias = alias i8* (), i8* ()* @local_decl + ; CHECK: define hidden i8 @local_a.cfi() { ; CHECK-NEXT: call void @external() ; CHECK-NEXT: call void @external_weak() @@ -37,8 +44,9 @@ declare extern_weak void @external_weak() ; CHECK: define internal i8 @local_b() { ; CHECK-NEXT: call i8 @local_a() -; CHECK: define void @local_decl() -; CHECK-NEXT: call void @local_decl() +; CHECK: define i8* @local_decl() +; CHECK-NEXT: call i8* @local_decl() +; CHECK-NEXT: ret i8* bitcast (i8* ()* @local_decl.cfi_jt to i8*) ; CHECK: declare void @external() ; CHECK: declare extern_weak void @external_weak() diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-functions-canonical-jump-tables.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-functions-canonical-jump-tables.ll new file mode 100644 index 0000000..ad775ee --- /dev/null +++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-functions-canonical-jump-tables.ll @@ -0,0 +1,23 @@ +; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s +; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck %s + +; Check that cfi.functions metadata has the expected contents. + +; CHECK: !"f1", i8 1 +; CHECK: !"f2", i8 1 +; CHECK: !"f3", i8 0 + +declare !type !1 void @f1() + +define void @f2() !type !1 { + ret void +} + +define void @f3() "cfi-canonical-jump-table" !type !1 { + ret void +} + +!llvm.module.flags = !{!0} + +!0 = !{i32 4, !"CFI Canonical Jump Tables", i32 0} +!1 = !{i32 0, !"typeid1"} -- 2.7.4