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Always treat DISubprogram reached by DIImportedEntity as needed. 

It is illegal to have a null entity in a DIImportedEntity, so
we must link in a DISubprogram metadata node referenced by one,
even if the associated function is not linked in or inlined anywhere.

Fixes PR26037.

llvm-svn: 257000
This commit is contained in:
Teresa Johnson 2016-01-07 00:06:27 +00:00
parent 0535003bef
commit b951558294
3 changed files with 64 additions and 1 deletions
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12
llvm/lib/Linker/IRMover.cpp
View File

@ -1211,6 +1211,16 @@ void IRLinker::findNeededSubprograms(ValueToValueMapTy &ValueMap) {
for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) {
auto *CU = cast<DICompileUnit>(CompileUnits->getOperand(I));
assert(CU && "Expected valid compile unit");
// Ensure that we don't remove subprograms referenced by DIImportedEntity.
// It is not legal to have a DIImportedEntity with a null entity.
// FIXME: The DISubprogram for functions not linked in but kept due to
// being referenced by a DIImportedEntity should also get their
// IsDefinition flag is unset.
SmallPtrSet<DISubprogram *, 8> ImportedEntitySPs;
for (auto *IE : CU->getImportedEntities()) {
if (auto *SP = dyn_cast<DISubprogram>(IE->getEntity()))
ImportedEntitySPs.insert(SP);
}
for (auto *Op : CU->getSubprograms()) {
// Unless we were doing function importing and deferred metadata linking,
// any needed SPs should have been mapped as they would be reached
@ -1218,7 +1228,7 @@ void IRLinker::findNeededSubprograms(ValueToValueMapTy &ValueMap) {
// function bodies, or from DILocation on inlined instructions).
assert(!(ValueMap.MD()[Op] && IsMetadataLinkingPostpass) &&
"DISubprogram shouldn't be mapped yet");
if (!ValueMap.MD()[Op])
if (!ValueMap.MD()[Op] && !ImportedEntitySPs.count(Op))
UnneededSubprograms.insert(Op);
}
}

23
llvm/test/Linker/Inputs/pr26037.ll Normal file
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@ -0,0 +1,23 @@
define i32 @main() #0 !dbg !4 {
entry:
%retval = alloca i32, align 4
store i32 0, i32* %retval, align 4
ret i32 0, !dbg !11
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!8, !9}
!llvm.ident = !{!10}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
!1 = !DIFile(filename: "main.cc", directory: "")
!2 = !{}
!3 = !{!4}
!4 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
!5 = !DISubroutineType(types: !6)
!6 = !{!7}
!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!8 = !{i32 2, !"Dwarf Version", i32 4}
!9 = !{i32 2, !"Debug Info Version", i32 3}
!10 = !{!"clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)"}
!11 = !DILocation(line: 1, column: 14, scope: !4)

30
llvm/test/Linker/pr26037.ll Normal file
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@ -0,0 +1,30 @@
; RUN: llvm-as %s -o %t.bc
; RUN: llvm-as %p/Inputs/pr26037.ll -o %t2.bc
; RUN: llvm-link -S -only-needed %t2.bc %t.bc | FileCheck %s
; CHECK: distinct !DISubprogram(name: "a"
; CHECK: !DIImportedEntity({{.*}}, entity:
define void @_ZN1A1aEv() #0 !dbg !4 {
entry:
ret void, !dbg !13
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!10, !11}
!llvm.ident = !{!12}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, imports: !8)
!1 = !DIFile(filename: "a2.cc", directory: "")
!2 = !{}
!3 = !{!4}
!4 = distinct !DISubprogram(name: "a", linkageName: "_ZN1A1aEv", scope: !5, file: !1, line: 5, type: !6, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
!5 = !DINamespace(name: "A", scope: null, file: !1, line: 1)
!6 = !DISubroutineType(types: !7)
!7 = !{null}
!8 = !{!9}
!9 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0, entity: !4, line: 2)
!10 = !{i32 2, !"Dwarf Version", i32 4}
!11 = !{i32 2, !"Debug Info Version", i32 3}
!12 = !{!"clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)"}
!13 = !DILocation(line: 6, column: 1, scope: !4)