[CodeGen][clang] Use module metadata to mark hotpatchable modules #142969

cjacek · 2025-06-05T13:57:47Z

No description provided.

cjacek · 2025-06-05T13:57:56Z

The main motivation is to enable writing llc-based tests for the emitted CodeView data

llvmbot · 2025-06-05T13:58:26Z

@llvm/pr-subscribers-debuginfo

@llvm/pr-subscribers-clang

Author: Jacek Caban (cjacek)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/142969.diff

6 Files Affected:

(modified) clang/lib/CodeGen/BackendUtil.cpp (-1)
(modified) clang/lib/CodeGen/CodeGenModule.cpp (+4)
(modified) clang/test/CodeGen/patchable-function-entry.c (+1)
(modified) llvm/include/llvm/Target/TargetOptions.h (+1-4)
(modified) llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp (+2-2)
(added) llvm/test/DebugInfo/PDB/hotpatch.test (+57)

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index cd5fc48c4a22b..2365f675b2dc3 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -473,7 +473,6 @@ 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;
 
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 468fc6e0e5c56..3529a5a70bd45 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1031,6 +1031,10 @@ 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);
diff --git a/clang/test/CodeGen/patchable-function-entry.c b/clang/test/CodeGen/patchable-function-entry.c
index 2acd748758490..b49f297abf7de 100644
--- a/clang/test/CodeGen/patchable-function-entry.c
+++ b/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}
diff --git a/llvm/include/llvm/Target/TargetOptions.h b/llvm/include/llvm/Target/TargetOptions.h
index fd8dad4f6f791..25bbb73e9dedc 100644
--- a/llvm/include/llvm/Target/TargetOptions.h
+++ b/llvm/include/llvm/Target/TargetOptions.h
@@ -150,7 +150,7 @@ namespace llvm {
           EmitAddrsig(false), BBAddrMap(false), EmitCallSiteInfo(false),
           SupportsDebugEntryValues(false), EnableDebugEntryValues(false),
           ValueTrackingVariableLocations(false), ForceDwarfFrameSection(false),
-          XRayFunctionIndex(true), DebugStrictDwarf(false), Hotpatch(false),
+          XRayFunctionIndex(true), DebugStrictDwarf(false),
           PPCGenScalarMASSEntries(false), JMCInstrument(false),
           EnableCFIFixup(false), MisExpect(false), XCOFFReadOnlyPointers(false),
           VerifyArgABICompliance(true),
@@ -363,9 +363,6 @@ namespace llvm {
     /// 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;
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index fc43bc6f7776d..49e26fcec48d6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -846,8 +846,8 @@ void CodeViewDebug::emitCompilerInformation() {
   }
   using ArchType = llvm::Triple::ArchType;
   ArchType Arch = MMI->getModule()->getTargetTriple().getArch();
-  if (Asm->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);
   }
 
diff --git a/llvm/test/DebugInfo/PDB/hotpatch.test b/llvm/test/DebugInfo/PDB/hotpatch.test
new file mode 100644
index 0000000000000..7ff15fa3c69a4
--- /dev/null
+++ b/llvm/test/DebugInfo/PDB/hotpatch.test
@@ -0,0 +1,57 @@
+; 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:      CodeViewDebugInfo [
+; CHECK-NEXT:   Section: .debug$S (4)
+; CHECK-NEXT:   Magic: 0x4
+; CHECK-NEXT:   Subsection [
+; CHECK-NEXT:     SubSectionType: Symbols (0xF1)
+; CHECK-NEXT:     SubSectionSize: 0x40
+; 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 [ (0x4000)
+; CHECK-NEXT:         HotPatch (0x4000)
+; CHECK-NEXT:       ]
+; CHECK-NEXT:       Machine: X64 (0xD0)
+; CHECK-NEXT:       FrontendVersion: 21.0.0.0
+; CHECK-NEXT:       BackendVersion: 21000.0.0.0
+; CHECK-NEXT:       VersionName: clang version 21.0.0git
+; CHECK-NEXT:     }
+; CHECK-NEXT:   ]

llvmbot · 2025-06-05T13:58:27Z

@llvm/pr-subscribers-clang-codegen

Author: Jacek Caban (cjacek)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/142969.diff

6 Files Affected:

(modified) clang/lib/CodeGen/BackendUtil.cpp (-1)
(modified) clang/lib/CodeGen/CodeGenModule.cpp (+4)
(modified) clang/test/CodeGen/patchable-function-entry.c (+1)
(modified) llvm/include/llvm/Target/TargetOptions.h (+1-4)
(modified) llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp (+2-2)
(added) llvm/test/DebugInfo/PDB/hotpatch.test (+57)

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index cd5fc48c4a22b..2365f675b2dc3 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -473,7 +473,6 @@ 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;
 
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 468fc6e0e5c56..3529a5a70bd45 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1031,6 +1031,10 @@ 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);
diff --git a/clang/test/CodeGen/patchable-function-entry.c b/clang/test/CodeGen/patchable-function-entry.c
index 2acd748758490..b49f297abf7de 100644
--- a/clang/test/CodeGen/patchable-function-entry.c
+++ b/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}
diff --git a/llvm/include/llvm/Target/TargetOptions.h b/llvm/include/llvm/Target/TargetOptions.h
index fd8dad4f6f791..25bbb73e9dedc 100644
--- a/llvm/include/llvm/Target/TargetOptions.h
+++ b/llvm/include/llvm/Target/TargetOptions.h
@@ -150,7 +150,7 @@ namespace llvm {
           EmitAddrsig(false), BBAddrMap(false), EmitCallSiteInfo(false),
           SupportsDebugEntryValues(false), EnableDebugEntryValues(false),
           ValueTrackingVariableLocations(false), ForceDwarfFrameSection(false),
-          XRayFunctionIndex(true), DebugStrictDwarf(false), Hotpatch(false),
+          XRayFunctionIndex(true), DebugStrictDwarf(false),
           PPCGenScalarMASSEntries(false), JMCInstrument(false),
           EnableCFIFixup(false), MisExpect(false), XCOFFReadOnlyPointers(false),
           VerifyArgABICompliance(true),
@@ -363,9 +363,6 @@ namespace llvm {
     /// 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;
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index fc43bc6f7776d..49e26fcec48d6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -846,8 +846,8 @@ void CodeViewDebug::emitCompilerInformation() {
   }
   using ArchType = llvm::Triple::ArchType;
   ArchType Arch = MMI->getModule()->getTargetTriple().getArch();
-  if (Asm->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);
   }
 
diff --git a/llvm/test/DebugInfo/PDB/hotpatch.test b/llvm/test/DebugInfo/PDB/hotpatch.test
new file mode 100644
index 0000000000000..7ff15fa3c69a4
--- /dev/null
+++ b/llvm/test/DebugInfo/PDB/hotpatch.test
@@ -0,0 +1,57 @@
+; 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:      CodeViewDebugInfo [
+; CHECK-NEXT:   Section: .debug$S (4)
+; CHECK-NEXT:   Magic: 0x4
+; CHECK-NEXT:   Subsection [
+; CHECK-NEXT:     SubSectionType: Symbols (0xF1)
+; CHECK-NEXT:     SubSectionSize: 0x40
+; 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 [ (0x4000)
+; CHECK-NEXT:         HotPatch (0x4000)
+; CHECK-NEXT:       ]
+; CHECK-NEXT:       Machine: X64 (0xD0)
+; CHECK-NEXT:       FrontendVersion: 21.0.0.0
+; CHECK-NEXT:       BackendVersion: 21000.0.0.0
+; CHECK-NEXT:       VersionName: clang version 21.0.0git
+; CHECK-NEXT:     }
+; CHECK-NEXT:   ]

aganea

This PR will all depend on the course taken on #142970

aganea · 2025-06-05T15:05:06Z

llvm/test/DebugInfo/PDB/hotpatch.test

This part of the test seems to be generated by the other PR, not this one specifically.

aganea · 2025-09-10T13:18:48Z

@cjacek Is this still relevant or has it been committed under a different form?

cjacek · 2025-09-11T21:03:08Z

I originally needed this commit to write a test case for #142970, when I was emitting the compiler info conditionally. Once we decided to enable it unconditionally, I could use a non-hotpatchable input in the test case, so this PR was no longer necessary.

That said, being able to specify hotpatch in tests may still be useful at some point. I’ll rebase the PR, but I don’t mind dropping it if you think it’s not worth changing.

cjacek requested review from aganea, dpaoliello, efriedma-quic and mstorsjo June 5, 2025 13:57

llvmbot added clang Clang issues not falling into any other category clang:codegen IR generation bugs: mangling, exceptions, etc. llvm:codegen debuginfo labels Jun 5, 2025

mstorsjo requested a review from zmodem June 5, 2025 13:58

cjacek mentioned this pull request Jun 5, 2025

[CodeGen][COFF] Always emit CodeView compiler info on Windows targets #142970

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aganea reviewed Jun 5, 2025

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llvm/test/DebugInfo/PDB/hotpatch.test Outdated

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aganea Jun 5, 2025

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This part of the test seems to be generated by the other PR, not this one specifically.

cjacek force-pushed the hotpatch-module branch from 108b56e to 52a318c Compare September 11, 2025 22:10

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

92ab85c

cjacek force-pushed the hotpatch-module branch from 52a318c to 92ab85c Compare September 11, 2025 23:10

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