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[Utils] Salvage debug info from all no-op casts 

We already try to salvage debug values from no-op bitcasts and inttoptr
instructions: we should handle ptrtoint instructions as well.

This saves an additional 24,444 debug values in a stage2 build of clang,
and (according to llvm-dwarfdump --statistics) provides an additional
289 unique source variables.

llvm-svn: 324982
This commit is contained in:
Vedant Kumar 2018-02-13 03:34:23 +00:00
parent 3b6de6fe1c
commit 388fac5de6
2 changed files with 17 additions and 4 deletions
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11
llvm/lib/Transforms/Utils/Local.cpp
View File

@ -1518,11 +1518,14 @@ void llvm::salvageDebugInfo(Instruction &I) {
doSalvage(DII, Ops);
};
if (isa<BitCastInst>(&I) || isa<IntToPtrInst>(&I)) {
// Bitcasts are entirely irrelevant for debug info. Rewrite dbg.value,
// dbg.addr, and dbg.declare to use the cast's source.
if (auto *CI = dyn_cast<CastInst>(&I)) {
if (!CI->isNoopCast(M.getDataLayout()))
return;
// No-op casts are irrelevant for debug info.
MetadataAsValue *CastSrc = wrapMD(I.getOperand(0));
for (auto *DII : DbgUsers) {
DII->setOperand(0, wrapMD(I.getOperand(0)));
DII->setOperand(0, CastSrc);
DEBUG(dbgs() << "SALVAGE: " << *DII << '\n');
}
} else if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {

10
llvm/test/Transforms/InstCombine/debuginfo-variables.ll
View File

@ -80,6 +80,13 @@ define void @test_srem(i64 %A) {
ret void
}
define void @test_ptrtoint(i64* %P) {
; CHECK-LABEL: @test_ptrtoint
; CHECK-NEXT: call void @llvm.dbg.value(metadata i64* %P, metadata !67, metadata !DIExpression()), !dbg !68
%1 = ptrtoint i64* %P to i64
ret void
}
; CHECK: !8 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !9)
; CHECK: !10 = !DILocalVariable(name: "2", scope: !5, file: !1, line: 2, type: !11)
; CHECK: !12 = !DILocation(line: 2, column: 1, scope: !5)
@ -114,3 +121,6 @@ define void @test_srem(i64 %A) {
; CHECK: !62 = !DILocalVariable(name: "12", scope: !60, file: !1, line: 22, type: !11)
; CHECK: !63 = !DILocation(line: 22, column: 1, scope: !60)
; CHECK: !67 = !DILocalVariable(name: "13", scope: !65, file: !1, line: 24, type: !11)
; CHECK: !68 = !DILocation(line: 24, column: 1, scope: !65)