[CodeGen][clang] Use module metadata to mark hotpatchable modules

Author: cjacek

clang/lib/CodeGen/BackendUtil.cpp

@@ -467,7 +467,6 @@ static bool initTargetOptions(const CompilerInstance &CI,
   Options.LoopAlignment = CodeGenOpts.LoopAlignment;
   Options.DebugStrictDwarf = CodeGenOpts.DebugStrictDwarf;
   Options.ObjectFilenameForDebug = CodeGenOpts.ObjectFilenameForDebug;
-  Options.Hotpatch = CodeGenOpts.HotPatch;
   Options.JMCInstrument = CodeGenOpts.JMCInstrument;
   Options.XCOFFReadOnlyPointers = CodeGenOpts.XCOFFReadOnlyPointers;
 

clang/lib/CodeGen/CodeGenModule.cpp

@@ -1136,6 +1136,10 @@ void CodeGenModule::Release() {
     // Function ID tables for EH Continuation Guard.
     getModule().addModuleFlag(llvm::Module::Warning, "ehcontguard", 1);
   }
+  if (CodeGenOpts.HotPatch) {
+    // Note if we are compiling with /hotpatch.
+    getModule().addModuleFlag(llvm::Module::Warning, "ms-hotpatch", 1);
+  }
   if (Context.getLangOpts().Kernel) {
     // Note if we are compiling with /kernel.
     getModule().addModuleFlag(llvm::Module::Warning, "ms-kernel", 1);

clang/test/CodeGen/patchable-function-entry.c

@@ -39,3 +39,4 @@ void f(void) {}
 // HOTPATCH: attributes #1 = { {{.*}} "patchable-function"="prologue-short-redirect"
 // HOTPATCH: attributes #2 = { {{.*}} "patchable-function"="prologue-short-redirect"
 // HOTPATCH: attributes #3 = { {{.*}} "patchable-function"="prologue-short-redirect"
+// HOTPATCH: !{{.}} = !{i32 2, !"ms-hotpatch", i32 1}

llvm/include/llvm/Target/TargetOptions.h

@@ -137,10 +137,9 @@ class TargetOptions {
         EmitCallSiteInfo(false), SupportsDebugEntryValues(false),
         EnableDebugEntryValues(false), ValueTrackingVariableLocations(false),
         ForceDwarfFrameSection(false), XRayFunctionIndex(true),
-        DebugStrictDwarf(false), Hotpatch(false),
-        PPCGenScalarMASSEntries(false), JMCInstrument(false),
-        EnableCFIFixup(false), MisExpect(false), XCOFFReadOnlyPointers(false),
-        VerifyArgABICompliance(true),
+        DebugStrictDwarf(false), PPCGenScalarMASSEntries(false),
+        JMCInstrument(false), EnableCFIFixup(false), MisExpect(false),
+        XCOFFReadOnlyPointers(false), VerifyArgABICompliance(true),
         FPDenormalMode(DenormalMode::IEEE, DenormalMode::IEEE) {}
 
   /// DisableFramePointerElim - This returns true if frame pointer elimination
@@ -347,9 +346,6 @@ class TargetOptions {
   /// By default, it is set to false.
   unsigned DebugStrictDwarf : 1;
 
-  /// Emit the hotpatch flag in CodeView debug.
-  unsigned Hotpatch : 1;
-
   /// Enables scalar MASS conversions
   unsigned PPCGenScalarMASSEntries : 1;
 

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

@@ -886,8 +886,8 @@ void CodeViewDebug::emitCompilerInformation() {
   }
   using ArchType = llvm::Triple::ArchType;
   ArchType Arch = MMI->getModule()->getTargetTriple().getArch();
-  if (CompilerInfoAsm->TM.Options.Hotpatch || Arch == ArchType::thumb ||
-      Arch == ArchType::aarch64) {
+  if (Arch == ArchType::thumb || Arch == ArchType::aarch64 ||
+      MMI->getModule()->getModuleFlag("ms-hotpatch")) {
     Flags |= static_cast<uint32_t>(CompileSym3Flags::HotPatch);
   }
 

llvm/test/DebugInfo/PDB/hotpatch.test

@@ -0,0 +1,40 @@
+; RUN: llc -filetype=obj -o - %s | llvm-readobj --codeview - | FileCheck %s
+
+; ModuleID = 'a.c'
+source_filename = "a.c"
+target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-windows-msvc19.33.0"
+
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local void @test() #0 !dbg !10 {
+entry:
+  ret void, !dbg !13
+}
+
+attributes #0 = { noinline nounwind optnone uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "patchable-function"="prologue-short-redirect" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 21.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "a.c", directory: "/tmp", checksumkind: CSK_MD5, checksum: "c59e1f6192de3124537b024248301dd1")
+!2 = !{i32 2, !"CodeView", i32 1}
+!3 = !{i32 2, !"ms-hotpatch", i32 1}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 2}
+!6 = !{i32 8, !"PIC Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 1, !"MaxTLSAlign", i32 65536}
+!9 = !{!"clang version 21.0.0git"}
+!10 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 1, type: !11, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0)
+!11 = !DISubroutineType(types: !12)
+!12 = !{null}
+!13 = !DILocation(line: 1, scope: !10)
+
+; CHECK:      Compile3Sym {
+; CHECK-NEXT:   Kind: S_COMPILE3 (0x113C)
+; CHECK-NEXT:   Language: C (0x0)
+; CHECK-NEXT:   Flags [ (0x4000)
+; CHECK-NEXT:     HotPatch (0x4000)
+; CHECK-NEXT:   ]