[CodeGen][COFF] Always emit CodeView compiler info on Windows targets

clang/lib/CodeGen/CodeGenModule.cpp

@@ -414,6 +414,11 @@ CodeGenModule::CodeGenModule(ASTContext &C,
       CodeGenOpts.CoverageNotesFile.size() ||
       CodeGenOpts.CoverageDataFile.size())
     DebugInfo.reset(new CGDebugInfo(*this));
+  else if (getTriple().isOSWindows())
+    // On Windows targets, we want to emit compiler info even if debug info is
+    // otherwise disabled. Use a temporary CGDebugInfo instance to emit only
+    // basic compiler metadata.
+    CGDebugInfo(*this);
 
   Block.GlobalUniqueCount = 0;
 
@@ -1051,7 +1056,7 @@ void CodeGenModule::Release() {
                               "StrictVTablePointersRequirement",
                               llvm::MDNode::get(VMContext, Ops));
   }
-  if (getModuleDebugInfo())
+  if (getModuleDebugInfo() || getTriple().isOSWindows())
     // We support a single version in the linked module. The LLVM
     // parser will drop debug info with a different version number
     // (and warn about it, too).

clang/test/CodeGen/debug-info-version-coff.c

@@ -0,0 +1,8 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang --target=x86_64-windows -g -S -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang --target=x86_64-windows -S -emit-llvm -o - %s | FileCheck %s
+int main (void) {
+  return 0;
+}
+
+// CHECK:  i32 2, !"Debug Info Version", i32 3}

clang/test/CodeGen/debug-info-version.c

@@ -1,3 +1,4 @@
+// REQUIRES: !system-windows
 // RUN: %clang -g -S -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang -S -emit-llvm -o - %s | FileCheck %s --check-prefix=NO_DEBUG
 int main (void) {

clang/test/CodeGenCXX/debug-info-coff.cpp

@@ -0,0 +1,37 @@
+// REQUIRES: x86-registered-target
+
+// Check that CodeView compiler version is emitted even when debug info is otherwise disabled.
+
+// RUN: %clang --target=i686-pc-windows-msvc -S -emit-llvm %s -o - | FileCheck --check-prefix=IR %s
+// IR: !llvm.dbg.cu = !{!0}
+// IR: !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version {{.*}}", isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug, splitDebugInlining: false, nameTableKind: None)
+
+// RUN: %clang --target=i686-pc-windows-msvc -c %s -o %t.o
+// RUN: llvm-readobj --codeview %t.o | FileCheck %s
+// CHECK:      CodeViewDebugInfo [
+// CHECK-NEXT:   Section: .debug$S (4)
+// CHECK-NEXT:   Magic: 0x4
+// CHECK-NEXT:   Subsection [
+// CHECK-NEXT:     SubSectionType: Symbols (0xF1)
+// CHECK-NEXT:     SubSectionSize:
+// CHECK-NEXT:     ObjNameSym {
+// CHECK-NEXT:       Kind: S_OBJNAME (0x1101)
+// CHECK-NEXT:       Signature: 0x0
+// CHECK-NEXT:       ObjectName:
+// CHECK-NEXT:     }
+// CHECK-NEXT:     Compile3Sym {
+// CHECK-NEXT:       Kind: S_COMPILE3 (0x113C)
+// CHECK-NEXT:       Language: Cpp (0x1)
+// CHECK-NEXT:       Flags [ (0x0)
+// CHECK-NEXT:       ]
+// CHECK-NEXT:       Machine: Pentium3 (0x7)
+// CHECK-NEXT:       FrontendVersion:
+// CHECK-NEXT:       BackendVersion:
+// CHECK-NEXT:       VersionName: clang version
+// CHECK-NEXT:     }
+// CHECK-NEXT:   ]
+// CHECK-NEXT: ]
+
+int main() {
+  return 0;
+}

clang/test/CodeGenCXX/debug-info-hotpatch-aarch64.cpp

@@ -11,12 +11,9 @@
 // RUN: llvm-pdbutil dump -symbols %t.obj | FileCheck %s --check-prefix=HOTPATCH
 // HOTPATCH: S_COMPILE3 [size = [[#]]]
 // HOTPATCH: flags = hot patchable
-///
-/// Unfortunately we need /Z7, Clang does not systematically generate S_COMPILE3.
-///
+//
 // RUN: %clang_cl --target=aarch64-pc-windows-msvc /c -o %t.obj -- %s
-// RUN: llvm-pdbutil dump -symbols %t.obj | FileCheck %s --check-prefix=NO-HOTPATCH
-// NO-HOTPATCH-NOT: flags = hot patchable
+// RUN: llvm-pdbutil dump -symbols %t.obj | FileCheck %s --check-prefix=HOTPATCH
 
 int main() {
   return 0;

clang/test/CodeGenCXX/debug-info-hotpatch-arm.cpp

@@ -11,12 +11,9 @@
 // RUN: llvm-pdbutil dump -symbols %t.obj | FileCheck %s --check-prefix=HOTPATCH
 // HOTPATCH: S_COMPILE3 [size = [[#]]]
 // HOTPATCH: flags = hot patchable
-///
-/// Unfortunately we need /Z7, Clang does not systematically generate S_COMPILE3.
-///
+//
 // RUN: %clang_cl --target=arm-pc-windows-msvc /c -o %t.obj -- %s
-// RUN: llvm-pdbutil dump -symbols %t.obj | FileCheck %s --check-prefix=NO-HOTPATCH
-// NO-HOTPATCH-NOT: flags = hot patchable
+// RUN: llvm-pdbutil dump -symbols %t.obj | FileCheck %s --check-prefix=HOTPATCH
 
 int main() {
   return 0;

clang/test/Frontend/ast-main.c

@@ -1,6 +1,6 @@
-// RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t1.ll -x c - < %s
+// RUN: env SDKROOT="/" %clang -emit-llvm -S -o - -x c - < %s | grep -v DIFile > %t1.ll
 // RUN: env SDKROOT="/" %clang -emit-ast -o %t.ast %s
-// RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t2.ll -x ast - < %t.ast
+// RUN: env SDKROOT="/" %clang -emit-llvm -S -o - -x ast - < %t.ast | grep -v DIFile > %t2.ll
 // RUN: diff %t1.ll %t2.ll
 
 int main(void) {

clang/test/Frontend/ast-main.cpp

@@ -1,6 +1,6 @@
-// RUN: env SDKROOT="/" %clang -Wno-error=return-type -emit-llvm -S -o %t1.ll -x c++ - < %s
+// RUN: env SDKROOT="/" %clang -Wno-error=return-type -emit-llvm -S -o - -x c++ - < %s | grep -v DIFile > %t1.ll
 // RUN: env SDKROOT="/" %clang -Wno-error=return-type -fno-delayed-template-parsing -emit-ast -o %t.ast %s
-// RUN: env SDKROOT="/" %clang -Wno-error=return-type -emit-llvm -S -o %t2.ll -x ast - < %t.ast
+// RUN: env SDKROOT="/" %clang -Wno-error=return-type -emit-llvm -S -o - -x ast - < %t.ast | grep -v DIFile > %t2.ll
 // RUN: diff %t1.ll %t2.ll
 
 // http://llvm.org/bugs/show_bug.cgi?id=15377

clang/test/Frontend/ir-support.c

@@ -4,16 +4,16 @@
 // We strip differing '.file' directives before comparing.
 
 // Reference output:
-// RUN: %clang_cc1 -S -o - %s | grep -v '\.file' > %t.s
+// RUN: %clang_cc1 -triple=x86_64-windows -S -o - %s | grep -v '\.file' > %t.s
 
 // LLVM bitcode:
-// RUN: %clang_cc1 -emit-llvm-bc -o %t.bc %s
-// RUN: %clang_cc1 -S -o - %t.bc | grep -v '\.file' > %t.bc.s
+// RUN: %clang_cc1 -triple=x86_64-windows -emit-llvm-bc -o %t.bc %s
+// RUN: %clang_cc1 -triple=x86_64-windows -S -o - %t.bc | grep -v '\.file' > %t.bc.s
 // RUN: diff %t.s %t.bc.s
 
 // LLVM IR source code:
-// RUN: %clang_cc1 -emit-llvm -o %t.ll %s
-// RUN: %clang_cc1 -S -o - %t.ll | grep -v '\.file' > %t.ll.s
+// RUN: %clang_cc1 -triple=x86_64-windows -emit-llvm -o %t.ll %s
+// RUN: %clang_cc1 -triple=x86_64-windows -S -o - %t.ll | grep -v '\.file' > %t.ll.s
 // RUN: diff %t.s %t.ll.s
 
 int f(void) { return 0; }

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -561,8 +561,11 @@ bool AsmPrinter::doInitialization(Module &M) {
 
   if (MAI->doesSupportDebugInformation()) {
     bool EmitCodeView = M.getCodeViewFlag();
-    if (EmitCodeView &&
-        (TM.getTargetTriple().isOSWindows() || TM.getTargetTriple().isUEFI()))
+    // On Windows targets, emit minimal CodeView compiler info even when debug
+    // info is disabled.
+    if ((TM.getTargetTriple().isOSWindows() &&
+         M.getNamedMetadata("llvm.dbg.cu")) ||
+        (TM.getTargetTriple().isUEFI() && EmitCodeView))
       Handlers.push_back(std::make_unique<CodeViewDebug>(this));
     if (!EmitCodeView || M.getDwarfVersion()) {
       if (hasDebugInfo()) {

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

@@ -125,6 +125,8 @@ static CPUType mapArchToCVCPUType(Triple::ArchType Type) {
     return CPUType::ARM64;
   case Triple::ArchType::mipsel:
     return CPUType::MIPS;
+  case Triple::ArchType::UnknownArch:
+    return CPUType::Unknown;
   default:
     report_fatal_error("target architecture doesn't map to a CodeView CPUType");
   }
@@ -611,21 +613,33 @@ static SourceLanguage MapDWLangToCVLang(unsigned DWLang) {
 }
 
 void CodeViewDebug::beginModule(Module *M) {
-  // If module doesn't have named metadata anchors or COFF debug section
-  // is not available, skip any debug info related stuff.
-  if (!Asm->hasDebugInfo() ||
-      !Asm->getObjFileLowering().getCOFFDebugSymbolsSection()) {
+  // If COFF debug section is not available, skip any debug info related stuff.
+  if (!Asm->getObjFileLowering().getCOFFDebugSymbolsSection()) {
     Asm = nullptr;
     return;
   }
 
+  CompilerInfoAsm = Asm;
   TheCPU = mapArchToCVCPUType(M->getTargetTriple().getArch());
 
   // Get the current source language.
-  const MDNode *Node = *M->debug_compile_units_begin();
+  const MDNode *Node;
+  if (Asm->hasDebugInfo()) {
+    Node = *M->debug_compile_units_begin();
+  } else {
+    // When emitting only compiler information, we may have only NoDebug CUs,
+    // which would be skipped by debug_compile_units_begin.
+    NamedMDNode *CUs = MMI->getModule()->getNamedMetadata("llvm.dbg.cu");
+    Node = *CUs->operands().begin();
+  }
   const auto *CU = cast<DICompileUnit>(Node);
 
   CurrentSourceLanguage = MapDWLangToCVLang(CU->getSourceLanguage());
+  if (!M->getCodeViewFlag() ||
+      CU->getEmissionKind() == DICompileUnit::NoDebug) {
+    Asm = nullptr;
+    return;
+  }
 
   collectGlobalVariableInfo();
 
@@ -636,7 +650,7 @@ void CodeViewDebug::beginModule(Module *M) {
 }
 
 void CodeViewDebug::endModule() {
-  if (!Asm || !Asm->hasDebugInfo())
+  if (!CompilerInfoAsm)
     return;
 
   // The COFF .debug$S section consists of several subsections, each starting
@@ -652,6 +666,8 @@ void CodeViewDebug::endModule() {
   emitObjName();
   emitCompilerInformation();
   endCVSubsection(CompilerInfo);
+  if (!Asm)
+    return;
 
   emitInlineeLinesSubsection();
 
@@ -788,7 +804,7 @@ void CodeViewDebug::emitTypeGlobalHashes() {
 void CodeViewDebug::emitObjName() {
   MCSymbol *CompilerEnd = beginSymbolRecord(SymbolKind::S_OBJNAME);
 
-  StringRef PathRef(Asm->TM.Options.ObjectFilenameForDebug);
+  StringRef PathRef(CompilerInfoAsm->TM.Options.ObjectFilenameForDebug);
   llvm::SmallString<256> PathStore(PathRef);
 
   if (PathRef.empty() || PathRef == "-") {
@@ -846,7 +862,7 @@ void CodeViewDebug::emitCompilerInformation() {
   }
   using ArchType = llvm::Triple::ArchType;
   ArchType Arch = MMI->getModule()->getTargetTriple().getArch();
-  if (Asm->TM.Options.Hotpatch || Arch == ArchType::thumb ||
+  if (CompilerInfoAsm->TM.Options.Hotpatch || Arch == ArchType::thumb ||
       Arch == ArchType::aarch64) {
     Flags |= static_cast<uint32_t>(CompileSym3Flags::HotPatch);
   }
@@ -1015,7 +1031,7 @@ void CodeViewDebug::switchToDebugSectionForSymbol(const MCSymbol *GVSym) {
   const MCSymbol *KeySym = GVSec ? GVSec->getCOMDATSymbol() : nullptr;
 
   MCSectionCOFF *DebugSec = cast<MCSectionCOFF>(
-      Asm->getObjFileLowering().getCOFFDebugSymbolsSection());
+      CompilerInfoAsm->getObjFileLowering().getCOFFDebugSymbolsSection());
   DebugSec = OS.getContext().getAssociativeCOFFSection(DebugSec, KeySym);
 
   OS.switchSection(DebugSec);

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h

@@ -98,6 +98,10 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
   /// The codeview CPU type used by the translation unit.
   codeview::CPUType TheCPU;
 
+  /// The AsmPrinter used for emitting compiler metadata. When only compiler
+  /// info is being emitted, DebugHandlerBase::Asm may be null.
+  AsmPrinter *CompilerInfoAsm = nullptr;
+
   static LocalVarDef createDefRangeMem(uint16_t CVRegister, int Offset);
 
   /// Similar to DbgVariable in DwarfDebug, but not dwarf-specific.

llvm/test/CodeGen/Generic/selection-dag-determinism.ll

@@ -1,8 +1,8 @@
-; RUN: llc -O2 -o %t1.o < %s
-; RUN: llc -O2 -o %t2.o < %s
-; RUN: llc -O2 -o %t3.o < %s
-; RUN: llc -O2 -o %t4.o < %s
-; RUN: llc -O2 -o %t5.o < %s
+; RUN: llc -O2 < %s > %t1.o
+; RUN: llc -O2 < %s > %t2.o
+; RUN: llc -O2 < %s > %t3.o
+; RUN: llc -O2 < %s > %t4.o
+; RUN: llc -O2 < %s > %t5.o
 ; RUN: cmp %t1.o %t2.o
 ; RUN: cmp %t1.o %t3.o
 ; RUN: cmp %t1.o %t4.o

llvm/test/DebugInfo/COFF/dwarf-headers.ll

@@ -43,6 +43,33 @@
 ; DWO-4: 0x00000000: Compile Unit: {{.*}} version = 0x0004, abbr_offset
 ; DWO-4: 0x0000000b: DW_TAG_compile_unit
 
+; Check that basic CodeView compiler info is emitted even when the DWARF debug format is used.
+; RUN: llc -dwarf-version=4 \
+; RUN:     -filetype=obj -O0 -mtriple=x86_64-unknown-windows-msvc < %s \
+; RUN:     | llvm-readobj --codeview - | FileCheck %s --check-prefix=CODEVIEW
+; CODEVIEW:      CodeViewDebugInfo [
+; CODEVIEW-NEXT:   Section: .debug$S (4)
+; CODEVIEW-NEXT:   Magic: 0x4
+; CODEVIEW-NEXT:   Subsection [
+; CODEVIEW-NEXT:     SubSectionType: Symbols (0xF1)
+; CODEVIEW-NEXT:     SubSectionSize: 0x90
+; CODEVIEW-NEXT:     ObjNameSym {
+; CODEVIEW-NEXT:       Kind: S_OBJNAME (0x1101)
+; CODEVIEW-NEXT:       Signature: 0x0
+; CODEVIEW-NEXT:       ObjectName:
+; CODEVIEW-NEXT:     }
+; CODEVIEW-NEXT:     Compile3Sym {
+; CODEVIEW-NEXT:       Kind: S_COMPILE3 (0x113C)
+; CODEVIEW-NEXT:       Language: Cpp (0x1)
+; CODEVIEW-NEXT:       Flags [ (0x0)
+; CODEVIEW-NEXT:       ]
+; CODEVIEW-NEXT:       Machine: X64 (0xD0)
+; CODEVIEW-NEXT:       FrontendVersion: 17.0.0.0
+; CODEVIEW-NEXT:       BackendVersion:
+; CODEVIEW-NEXT:       VersionName: clang version 17.0.0
+; CODEVIEW-NEXT:     }
+; CODEVIEW-NEXT:   ]
+; CODEVIEW-NEXT: ]
 
 ; ModuleID = 't.cpp'
 source_filename = "t.cpp"

llvm/test/DebugInfo/COFF/emission-kind-no-codeview.ll

@@ -0,0 +1,38 @@
+; RUN: llc -filetype=obj -o - < %s | llvm-readobj --codeview - | FileCheck %s
+; Check that basic CodeView compiler info is emitted even when the CodeView flag is not set.
+
+; CHECK-NOT:  CodeViewTypes
+; CHECK:      CodeViewDebugInfo [
+; CHECK-NEXT:   Section: .debug$S (4)
+; CHECK-NEXT:   Magic: 0x4
+; CHECK-NEXT:   Subsection [
+; CHECK-NEXT:     SubSectionType: Symbols (0xF1)
+; CHECK-NEXT:     SubSectionSize: 0x2C
+; CHECK-NEXT:     ObjNameSym {
+; CHECK-NEXT:       Kind: S_OBJNAME (0x1101)
+; CHECK-NEXT:       Signature: 0x0
+; CHECK-NEXT:       ObjectName:
+; CHECK-NEXT:     }
+; CHECK-NEXT:     Compile3Sym {
+; CHECK-NEXT:       Kind: S_COMPILE3 (0x113C)
+; CHECK-NEXT:       Language: C (0x0)
+; CHECK-NEXT:       Flags [ (0x0)
+; CHECK-NEXT:       ]
+; CHECK-NEXT:       Machine: X64 (0xD0)
+; CHECK-NEXT:       FrontendVersion:
+; CHECK-NEXT:       BackendVersion:
+; CHECK-NEXT:       VersionName: clang
+; CHECK-NEXT:     }
+; CHECK-NEXT:   ]
+; CHECK-NEXT: ]
+
+source_filename = "empty"
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.0.24215"
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "clang", emissionKind: NoDebug)
+!1 = !DIFile(filename: "empty", directory: "path/to")
+!2 = !{i32 2, !"Debug Info Version", i32 3}

llvm/test/DebugInfo/COFF/emission-kind-no-debug.ll

@@ -1,8 +1,30 @@
 ; RUN: llc -filetype=obj -o - < %s | llvm-readobj --codeview - | FileCheck %s
-; Check that debug info isn't emitted for CodeView with emissionKind NoDebug
+; Check that only basic compiler info is emitted for CodeView with emissionKind NoDebug
 
-; CHECK-NOT:      CodeViewTypes
-; CHECK-NOT:      CodeViewDebugInfo
+; CHECK-NOT:  CodeViewTypes
+; CHECK:      CodeViewDebugInfo [
+; CHECK-NEXT:   Section: .debug$S (4)
+; CHECK-NEXT:   Magic: 0x4
+; CHECK-NEXT:   Subsection [
+; CHECK-NEXT:     SubSectionType: Symbols (0xF1)
+; CHECK-NEXT:     SubSectionSize: 0x2C
+; CHECK-NEXT:     ObjNameSym {
+; CHECK-NEXT:       Kind: S_OBJNAME (0x1101)
+; CHECK-NEXT:       Signature: 0x0
+; CHECK-NEXT:       ObjectName:
+; CHECK-NEXT:     }
+; CHECK-NEXT:     Compile3Sym {
+; CHECK-NEXT:       Kind: S_COMPILE3 (0x113C)
+; CHECK-NEXT:       Language: C (0x0)
+; CHECK-NEXT:       Flags [ (0x0)
+; CHECK-NEXT:       ]
+; CHECK-NEXT:       Machine: X64 (0xD0)
+; CHECK-NEXT:       FrontendVersion:
+; CHECK-NEXT:       BackendVersion:
+; CHECK-NEXT:       VersionName: clang
+; CHECK-NEXT:     }
+; CHECK-NEXT:   ]
+; CHECK-NEXT: ]
 
 source_filename = "empty"
 target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"

llvm/test/DebugInfo/COFF/fission-cu.ll

@@ -107,11 +107,11 @@ source_filename = "test/DebugInfo/X86/fission-cu.ll"
 ; For COFF we should have this set of relocations for the debug info section
 ;
 ; OBJ: .debug_info
-; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_abbrev (6)
-; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_line (26)
-; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_str (10)
-; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_str (10)
-; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_addr (20)
+; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_abbrev (8)
+; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_line (28)
+; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_str (12)
+; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_str (12)
+; OBJ-NEXT: IMAGE_REL_AMD64_SECREL .debug_addr (22)
 ; OBJ-NEXT: }
 
 ; HDR-NOT: .debug_aranges