[WebAssembly] Add support for DWARF type units

    Since Wasm comdat sections work similarly to ELF, we can use that mechanism
    to eliminate duplicate dwarf type information in the same way.

    Differential Revision: https://reviews.llvm.org/D88603

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index dde4e8d..a15067b 100644 (file)
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3989,7 +3989,7 @@ static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
 
   if (Args.hasFlag(options::OPT_fdebug_types_section,
                    options::OPT_fno_debug_types_section, false)) {
-    if (!T.isOSBinFormatELF()) {
+    if (!(T.isOSBinFormatELF() || T.isOSBinFormatWasm())) {
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << Args.getLastArg(options::OPT_fdebug_types_section)
                  ->getAsString(Args)

diff --git a/clang/test/Driver/debug-options.c b/clang/test/Driver/debug-options.c
index 1be976d..bedc9d0 100644 (file)
--- a/clang/test/Driver/debug-options.c
+++ b/clang/test/Driver/debug-options.c
@@ -214,6 +214,9 @@
 // RUN: %clang -### -fdebug-types-section -fno-debug-types-section -target x86_64-unknown-linux %s 2>&1 \
 // RUN:        | FileCheck -check-prefix=NOFDTS %s
 //
+// RUN: %clang -### -fdebug-types-section -target wasm32-unknown-unknown %s 2>&1 \
+// RUN:        | FileCheck -check-prefix=FDTS %s
+//
 // RUN: %clang -### -fdebug-types-section -target x86_64-apple-darwin %s 2>&1 \
 // RUN:        | FileCheck -check-prefix=FDTSE %s
 //

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index e460402..859956e 100644 (file)
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -394,8 +394,9 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
     UseSectionsAsReferences = DwarfSectionsAsReferences == Enable;
 
   // Don't generate type units for unsupported object file formats.
-  GenerateTypeUnits =
-      A->TM.getTargetTriple().isOSBinFormatELF() && GenerateDwarfTypeUnits;
+  GenerateTypeUnits = (A->TM.getTargetTriple().isOSBinFormatELF() ||
+                       A->TM.getTargetTriple().isOSBinFormatWasm()) &&
+                      GenerateDwarfTypeUnits;
 
   TheAccelTableKind = computeAccelTableKind(
       DwarfVersion, GenerateTypeUnits, DebuggerTuning, A->TM.getTargetTriple());

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index d8ea0a8..1349494 100644 (file)
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -963,9 +963,14 @@ MCSection *MCObjectFileInfo::getDwarfComdatSection(const char *Name,
   case Triple::ELF:
     return Ctx->getELFSection(Name, ELF::SHT_PROGBITS, ELF::SHF_GROUP, 0,
                               utostr(Hash));
+  case Triple::Wasm:
+    // FIXME: When using dwarf 5, the .debug_info section is used for type units
+    // but that section already exists, so attempting to get it as a comdate
+    // section triggers an assert.
+    return Ctx->getWasmSection(Name, SectionKind::getMetadata(), utostr(Hash),
+                               MCContext::GenericSectionID);
   case Triple::MachO:
   case Triple::COFF:
-  case Triple::Wasm:
   case Triple::GOFF:
   case Triple::XCOFF:
   case Triple::UnknownObjectFormat:

diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index f81a83d..2f1277e 100644 (file)
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -1378,9 +1378,6 @@ uint64_t WasmObjectWriter::writeOneObject(MCAssembler &Asm,
       MCSymbol *Begin = Sec.getBeginSymbol();
       if (Begin) {
         WasmIndices[cast<MCSymbolWasm>(Begin)] = CustomSections.size();
-        if (SectionName != Begin->getName())
-          report_fatal_error("section name and begin symbol should match: " +
-                             Twine(SectionName));
       }
 
       // Separate out the producers and target features sections

diff --git a/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll b/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll
new file mode 100644 (file)
index 0000000..fa244d9
--- /dev/null
+++ b/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll
@@ -0,0 +1,117 @@
+; RUN: llc -dwarf-version=4 -generate-type-units \
+; RUN:     -filetype=obj -O0 -mtriple=wasm32-unknown-unknown < %s \
+; RUN:     | llvm-dwarfdump -v - | FileCheck %s --check-prefix=SINGLE-4
+
+; RUN: llc -split-dwarf-file=foo.dwo -split-dwarf-output=%t.dwo \
+; RUN:     -dwarf-version=4 -generate-type-units \
+; RUN:     -filetype=obj -O0 -mtriple=wasm32-unknown-unknown < %s \
+; RUN:     | llvm-dwarfdump -v - | FileCheck %s --check-prefix=O-4
+; RUN: llvm-dwarfdump -v %t.dwo | FileCheck %s --check-prefix=DWO-4
+
+; TODO: enable testing for dwarf v5 with type units
+; (See the FIXME in MCObjectFileInfo::getDwarfComdatSection)
+; RU N: llc -dwarf-version=5 -generate-type-units \
+; RU N:     -filetype=obj -O0 -mtriple= < %s \
+; RU N:     | llvm-dwarfdump -v - | FileCheck %s --check-prefix=SINGLE-5
+
+; RU N: llc -split-dwarf-file=foo.dwo -split-dwarf-output=%t.dwo \
+; RU N:     -dwarf-version=5 -generate-type-units \
+; RU N:     -filetype=obj -O0 -mtriple= < %s \
+; RU N:     | llvm-dwarfdump -v - | FileCheck %s --check-prefix=O-5
+; RU N: llvm-dwarfdump -v %t.dwo | FileCheck %s --check-prefix=DWO-5
+
+; This test is derived from test/CodeGen/X86/dwarf-headers.ll
+
+; Looking for DWARF headers to be generated correctly.
+; There are 8 variants with 5 formats: v4 CU, v4 TU, v5 normal/partial CU,
+; v5 skeleton/split CU, v5 normal/split TU.  Some v5 variants differ only
+; in the unit_type code, and the skeleton/split CU differs from normal/partial
+; by having one extra field (dwo_id).
+; (v2 thru v4 CUs are all the same, and TUs were invented in v4,
+; so we don't bother checking older versions.)
+
+; Test case built from:
+;struct S {
+;  int s1;
+;};
+;
+;S s;
+
+; Verify the v4 non-split headers.
+; Note that we check the exact offset of the DIEs because that tells us
+; the length of the header.
+;
+; SINGLE-4: .debug_info contents:
+; SINGLE-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
+; SINGLE-4: 0x0000000b: DW_TAG_compile_unit
+;
+; SINGLE-4: .debug_types contents:
+; SINGLE-4: 0x00000000: Type Unit: {{.*}} version = 0x0004, abbr_offset
+; SINGLE-4: 0x00000017: DW_TAG_type_unit
+
+; Verify the v4 split headers.
+;
+; O-4: .debug_info contents:
+; O-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
+; O-4: 0x0000000b: DW_TAG_compile_unit
+;
+; DWO-4: .debug_info.dwo contents:
+; DWO-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
+; DWO-4: 0x0000000b: DW_TAG_compile_unit
+;
+; DWO-4: .debug_types.dwo contents:
+; DWO-4: 0x00000000: Type Unit: {{.*}} version = 0x0004, abbr_offset
+; DWO-4: 0x00000017: DW_TAG_type_unit
+
+; Verify the v5 non-split headers. Type units come first.
+; All .debug_info sections are reported in one go, but the offset resets for
+; each new section.
+;
+; SINGLE-5: .debug_info contents:
+; SINGLE-5: 0x00000000: Type Unit: {{.*}} version = 0x0005, unit_type = DW_UT_type, abbr_offset
+; SINGLE-5: 0x00000018: DW_TAG_type_unit
+; SINGLE-5-NOT: contents:
+; SINGLE-5: 0x00000000: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_compile, abbr_offset
+; SINGLE-5: 0x0000000c: DW_TAG_compile_unit
+
+; Verify the v5 split headers.
+;
+; O-5: .debug_info contents:
+; O-5: 0x00000000: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_skeleton, abbr_offset
+; O-5-SAME:        DWO_id = 0xccd7e58ef8bf4aa6
+; O-5: 0x00000014: DW_TAG_skeleton_unit 
+;
+; DWO-5: .debug_info.dwo contents:
+; DWO-5: 0x00000000: Type Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_type, abbr_offset
+; DWO-5: 0x00000018: DW_TAG_type_unit
+; DWO-5: 0x00000033: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset
+; DWO-5-SAME:        DWO_id = 0xccd7e58ef8bf4aa6
+; DWO-5: 0x00000047: DW_TAG_compile_unit
+
+
+; ModuleID = 't.cpp'
+source_filename = "t.cpp"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+%struct.S = type { i32 }
+
+@s = global %struct.S zeroinitializer, align 4, !dbg !0
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!10, !11}
+!llvm.ident = !{!12}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "s", scope: !2, file: !3, line: 5, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 5.0.0 (trunk 295942)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "t.cpp", directory: "/home/probinson/projects/scratch")
+!4 = !{}
+!5 = !{!0}
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !3, line: 1, size: 32, elements: !7, identifier: "_ZTS1S")
+!7 = !{!8}
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "s1", scope: !6, file: !3, line: 2, baseType: !9, size: 32)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !{i32 2, !"Dwarf Version", i32 4}
+!11 = !{i32 2, !"Debug Info Version", i32 3}
+!12 = !{!"clang version 5.0.0 (trunk 295942)"}