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[FastISel] Lower `llvm.dbg.value(undef, ...` correctly. 

Summary:
Instead of just dropping them.

<rdar://problem/58657146>

Reviewers: aprantl, vsk, ab, paquette, echristo

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72877
This commit is contained in:
Davide Italiano 2020-01-16 14:02:09 -08:00
parent 1b1022b42a
commit 30a8865142
2 changed files with 33 additions and 4 deletions
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7
llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
View File

@ -1412,9 +1412,9 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
const Value *V = DI->getValue();
assert(DI->getVariable()->isValidLocationForIntrinsic(DbgLoc) &&
"Expected inlined-at fields to agree");
if (!V) {
if (!V || isa<UndefValue>(V)) {
// Currently the optimizer can produce this; insert an undef to
// help debugging. Probably the optimizer should not do this.
// help debugging.
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, false, 0U,
DI->getVariable(), DI->getExpression());
} else if (const auto *CI = dyn_cast<ConstantInt>(V)) {
@ -1442,8 +1442,7 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, IsIndirect, Reg,
DI->getVariable(), DI->getExpression());
} else {
// We can't yet handle anything else here because it would require
// generating code, thus altering codegen because of debug info.
// We don't know how to handle other cases, so we drop.
LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
}
return true;

30
llvm/test/CodeGen/AArch64/fastisel-debugvalue-undef.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: llc -O0 -fast-isel=1 -o - -print-after="finalize-isel" %s 2>&1 | FileCheck %s
; Check that we emit a DBG_VALUE for the `@llvm.dbg.value` which has `undef` has first arg.
target triple = "arm64-apple-ios13.4.0"
define void @foo() !dbg !6 {
; CHECK: DBG_VALUE $noreg, $noreg, !"1", !DIExpression()
call void @llvm.dbg.value(metadata i32* undef, metadata !9, metadata !DIExpression()), !dbg !11
ret void, !dbg !12
}
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.debugify = !{!3, !4}
!llvm.module.flags = !{!5}
!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "t.ll", directory: "/")
!2 = !{}
!3 = !{i32 2}
!4 = !{i32 1}
!5 = !{i32 2, !"Debug Info Version", i32 3}
!6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
!7 = !DISubroutineType(types: !2)
!8 = !{!9}
!9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
!11 = !DILocation(line: 1, column: 1, scope: !6)
!12 = !DILocation(line: 2, column: 1, scope: !6)