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[CodeGen] don't emit addrsig symbol if it's used only by metadata

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Value only used by metadata can be removed from .addrsig table.
This solves the undefined symbol error when enabling addrsig table on COFF LTO.

Differential Revision: https://reviews.llvm.org/D101512
This commit is contained in:
Zequan Wu 2021-04-28 21:25:51 -07:00
parent be01b091af
commit cab48e2f0e
4 changed files with 54 additions and 4 deletions
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3
llvm/include/llvm/IR/Value.h
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@ -565,6 +565,9 @@ public:
/// Return true if there is metadata referencing this value.
bool isUsedByMetadata() const { return IsUsedByMD; }
// Return true if this value is only transitively referenced by metadata.
bool isTransitiveUsedByMetadataOnly() const;
protected:
/// Get the current metadata attachments for the given kind, if any.
///

9
llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
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@ -1847,11 +1847,12 @@ bool AsmPrinter::doFinalization(Module &M) {
if (TM.Options.EmitAddrsig) {
// Emit address-significance attributes for all globals.
OutStreamer->emitAddrsig();
for (const GlobalValue &GV : M.global_values())
if (!GV.use_empty() && !GV.isThreadLocal() &&
!GV.hasDLLImportStorageClass() && !GV.getName().startswith("llvm.") &&
!GV.hasAtLeastLocalUnnamedAddr())
for (const GlobalValue &GV : M.global_values()) {
if (!GV.use_empty() && !GV.isTransitiveUsedByMetadataOnly() &&
!GV.isThreadLocal() && !GV.hasDLLImportStorageClass() &&
!GV.getName().startswith("llvm.") && !GV.hasAtLeastLocalUnnamedAddr())
OutStreamer->emitAddrsigSym(getSymbol(&GV));
}
}
// Emit symbol partition specifications (ELF only).

21
llvm/lib/IR/Value.cpp
View File

@ -980,6 +980,27 @@ bool Value::isSwiftError() const {
return Alloca->isSwiftError();
}
bool Value::isTransitiveUsedByMetadataOnly() const {
if (use_empty())
return false;
llvm::SmallVector<const User *, 32> WorkList;
llvm::SmallPtrSet<const User *, 32> Visited;
WorkList.insert(WorkList.begin(), user_begin(), user_end());
while (!WorkList.empty()) {
const User *U = WorkList.back();
WorkList.pop_back();
Visited.insert(U);
// If it is transitively used by a global value or a non-constant value,
// it's obviously not only used by metadata.
if (!isa<Constant>(U) || isa<GlobalValue>(U))
return false;
for (const User *UU : U->users())
if (!Visited.count(UU))
WorkList.push_back(UU);
}
return true;
}
//===----------------------------------------------------------------------===//
// ValueHandleBase Class
//===----------------------------------------------------------------------===//

25
llvm/test/CodeGen/X86/addrsig.ll
View File

@ -19,9 +19,20 @@ define void @f1() {
%a2 = bitcast i32* @a2 to i8*
%i1 = bitcast void()* @i1 to i8*
%i2 = bitcast void()* @i2 to i8*
call void @llvm.dbg.value(metadata i8* bitcast (void()* @metadata_f1 to i8*), metadata !5, metadata !DIExpression()), !dbg !7
call void @llvm.dbg.value(metadata i8* bitcast (void()* @metadata_f2 to i8*), metadata !5, metadata !DIExpression()), !dbg !7
call void @f4(i8* bitcast (void()* @metadata_f2 to i8*))
unreachable
}
declare void @f4(i8*) unnamed_addr
; CHECK-NOT: .addrsig_sym metadata_f1
declare void @metadata_f1()
; CHECK: .addrsig_sym metadata_f2
declare void @metadata_f2()
; CHECK-NOT: .addrsig_sym f2
define internal void @f2() local_unnamed_addr {
unreachable
@ -55,3 +66,17 @@ declare void @f3() unnamed_addr
@i1 = ifunc void(), void()* @f1
; CHECK-NOT: .addrsig_sym i2
@i2 = internal local_unnamed_addr ifunc void(), void()* @f2
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
!1 = !DIFile(filename: "a", directory: "")
!2 = !{i32 2, !"Debug Info Version", i32 3}
!3 = distinct !DISubprogram(scope: null, isLocal: false, isDefinition: true, isOptimized: false, unit: !0)
!4 = !DILocation(line: 0, scope: !3)
!5 = !DILocalVariable(scope: !6)
!6 = distinct !DISubprogram(scope: null, isLocal: false, isDefinition: true, isOptimized: false, unit: !0)
!7 = !DILocation(line: 0, scope: !6, inlinedAt: !4)