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[StripDebugInfo] Reuse DebugInfoFinder for findind Live CUs

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Previous search does not take into account @llvm.dbg.* intrinsics
and debug types information while DebugInfoFinder takes into account
such information.

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D145239
This commit is contained in:
Maksim Sabianin 2023-03-03 15:20:27 -08:00 committed by Alexey Bader
parent a65678b35b
commit b056c1cb1b
2 changed files with 45 additions and 50 deletions
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58
llvm/lib/Transforms/IPO/StripSymbols.cpp
View File

@ -176,44 +176,6 @@ static bool stripDebugDeclareImpl(Module &M) {
return true;
}
/// Collects compilation units referenced by functions or lexical scopes.
/// Accepts any DIScope and uses recursive bottom-up approach to reach either
/// DISubprogram or DILexicalBlockBase.
static void
collectCUsWithScope(const DIScope *Scope, std::set<DICompileUnit *> &LiveCUs,
SmallPtrSet<const DIScope *, 8> &VisitedScopes) {
if (!Scope)
return;
auto InS = VisitedScopes.insert(Scope);
if (!InS.second)
return;
if (const auto *SP = dyn_cast<DISubprogram>(Scope)) {
if (SP->getUnit())
LiveCUs.insert(SP->getUnit());
return;
}
if (const auto *LB = dyn_cast<DILexicalBlockBase>(Scope)) {
const DISubprogram *SP = LB->getSubprogram();
if (SP && SP->getUnit())
LiveCUs.insert(SP->getUnit());
return;
}
collectCUsWithScope(Scope->getScope(), LiveCUs, VisitedScopes);
}
static void
collectCUsForInlinedFuncs(const DILocation *Loc,
std::set<DICompileUnit *> &LiveCUs,
SmallPtrSet<const DIScope *, 8> &VisitedScopes) {
if (!Loc || !Loc->getInlinedAt())
return;
collectCUsWithScope(Loc->getScope(), LiveCUs, VisitedScopes);
collectCUsForInlinedFuncs(Loc->getInlinedAt(), LiveCUs, VisitedScopes);
}
static bool stripDeadDebugInfoImpl(Module &M) {
bool Changed = false;
@ -241,19 +203,15 @@ static bool stripDeadDebugInfoImpl(Module &M) {
}
std::set<DICompileUnit *> LiveCUs;
SmallPtrSet<const DIScope *, 8> VisitedScopes;
// Any CU is live if is referenced from a subprogram metadata that is attached
// to a function defined or inlined in the module.
for (const Function &Fn : M.functions()) {
collectCUsWithScope(Fn.getSubprogram(), LiveCUs, VisitedScopes);
for (const_inst_iterator I = inst_begin(&Fn), E = inst_end(&Fn); I != E;
++I) {
if (!I->getDebugLoc())
continue;
const DILocation *DILoc = I->getDebugLoc().get();
collectCUsForInlinedFuncs(DILoc, LiveCUs, VisitedScopes);
}
DebugInfoFinder LiveCUFinder;
for (const Function &F : M.functions()) {
if (auto *SP = cast_or_null<DISubprogram>(F.getSubprogram()))
LiveCUFinder.processSubprogram(SP);
for (const Instruction &I : instructions(F))
LiveCUFinder.processInstruction(M, I);
}
auto FoundCUs = LiveCUFinder.compile_units();
LiveCUs.insert(FoundCUs.begin(), FoundCUs.end());
bool HasDeadCUs = false;
for (DICompileUnit *DIC : F.compile_units()) {

37
llvm/test/Transforms/StripSymbols/find-live-cu.ll Normal file
View File

@ -0,0 +1,37 @@
; This test checks that strip-dead-debug-info pass doesn't delete debug compile
; units if they are used by @llvm.dbg.* intrinsics
; RUN: opt -passes='strip-dead-debug-info,verify' %s -S | FileCheck %s
; CHECK: !llvm.dbg.cu = !{!{{[0-9]+}}, !{{[0-9]+}}}
; CHECK-COUNT-2: !DICompileUnit
declare void @llvm.dbg.value(metadata, metadata, metadata)
define void @func() {
%a = alloca i64
call void @llvm.dbg.value(metadata ptr %a, metadata !7, metadata !DIExpression()), !dbg !9
ret void
}
!llvm.dbg.cu = !{!0, !1}
!llvm.module.flags = !{!10}
; We have two different compile units to able to check different paths of
; finding compile units (intrinsic argument and attached location to instruction)
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !11)
!1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !11)
!2 = distinct !DISubprogram(name: "func", unit: !0)
!3 = distinct !DICompositeType(tag: DW_TAG_class_type, scope: !2)
!4 = !DIDerivedType(tag: DW_TAG_member, scope: !3, baseType: !5)
!5 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !6)
!6 = !DIBasicType(tag: DW_TAG_base_type)
!7 = !DILocalVariable(name: "a", type: !5, scope: !8)
!8 = distinct !DISubprogram(name: "func", unit: !1)
!9 = !DILocation(scope: !8)
!10 = !{i32 2, !"Debug Info Version", i32 3}
!11 = !DIFile(filename: "a", directory: "")