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-rw-r--r--llvm/lib/Transforms/Utils/Local.cpp22
-rw-r--r--llvm/test/DebugInfo/X86/dbg-value-dropped-instcombine.ll76
-rw-r--r--llvm/unittests/Transforms/Utils/LocalTest.cpp7
3 files changed, 88 insertions, 17 deletions
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index aa1341eea05..eaccaa1c4ac 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1732,7 +1732,7 @@ DIExpression *llvm::salvageDebugInfoImpl(Instruction &I,
using DbgValReplacement = Optional<DIExpression *>;
/// Point debug users of \p From to \p To using exprs given by \p RewriteExpr,
-/// possibly moving/deleting users to prevent use-before-def. Returns true if
+/// possibly moving/undefing users to prevent use-before-def. Returns true if
/// changes are made.
static bool rewriteDebugUsers(
Instruction &From, Value &To, Instruction &DomPoint, DominatorTree &DT,
@@ -1745,7 +1745,7 @@ static bool rewriteDebugUsers(
// Prevent use-before-def of To.
bool Changed = false;
- SmallPtrSet<DbgVariableIntrinsic *, 1> DeleteOrSalvage;
+ SmallPtrSet<DbgVariableIntrinsic *, 1> UndefOrSalvage;
if (isa<Instruction>(&To)) {
bool DomPointAfterFrom = From.getNextNonDebugInstruction() == &DomPoint;
@@ -1760,14 +1760,14 @@ static bool rewriteDebugUsers(
// Users which otherwise aren't dominated by the replacement value must
// be salvaged or deleted.
} else if (!DT.dominates(&DomPoint, DII)) {
- DeleteOrSalvage.insert(DII);
+ UndefOrSalvage.insert(DII);
}
}
}
// Update debug users without use-before-def risk.
for (auto *DII : Users) {
- if (DeleteOrSalvage.count(DII))
+ if (UndefOrSalvage.count(DII))
continue;
LLVMContext &Ctx = DII->getContext();
@@ -1781,18 +1781,10 @@ static bool rewriteDebugUsers(
Changed = true;
}
- if (!DeleteOrSalvage.empty()) {
+ if (!UndefOrSalvage.empty()) {
// Try to salvage the remaining debug users.
- Changed |= salvageDebugInfo(From);
-
- // Delete the debug users which weren't salvaged.
- for (auto *DII : DeleteOrSalvage) {
- if (DII->getVariableLocation() == &From) {
- LLVM_DEBUG(dbgs() << "Erased UseBeforeDef: " << *DII << '\n');
- DII->eraseFromParent();
- Changed = true;
- }
- }
+ salvageDebugInfoOrMarkUndef(From);
+ Changed = true;
}
return Changed;
diff --git a/llvm/test/DebugInfo/X86/dbg-value-dropped-instcombine.ll b/llvm/test/DebugInfo/X86/dbg-value-dropped-instcombine.ll
new file mode 100644
index 00000000000..18e51b6fabd
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/dbg-value-dropped-instcombine.ll
@@ -0,0 +1,76 @@
+; RUN: opt -instcombine -S %s -o - | FileCheck %s
+
+; In pr40648 one of two dbg.values used to describe the variable bumble was
+; being dropped by instcombine. Test that both dbg.values survive instcombine.
+
+; $ clang -O0 -Xclang -disable-O0-optnone -g bees.c -emit-llvm -S -o - \
+; | opt -opt-bisect-limit=10 -O2 -o -
+; $ cat bees.c
+; struct bees {
+; int a;
+; int b;
+; }
+
+; int global = 0;
+
+; struct bees foo(struct bees bumble)
+; {
+; global = 1;
+; int temp = bumble.a + bumble.b;
+; return bumble;
+; }
+
+; CHECK: define dso_local i64 @foo
+; CHECK: @llvm.dbg.value({{.*}}, metadata ![[BEE:[0-9]+]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)),
+; CHECK: @llvm.dbg.value(metadata i32 undef, metadata ![[BEE]], metadata !DIExpression(DW_OP_LLVM_fragment, 32, 32)),
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-unknown"
+
+@global = dso_local local_unnamed_addr global i32 0, align 4, !dbg !0
+
+define dso_local i64 @foo(i64 %bumble.coerce) local_unnamed_addr !dbg !11 {
+entry:
+ %bumble.sroa.0.0.extract.trunc = trunc i64 %bumble.coerce to i32
+ call void @llvm.dbg.value(metadata i32 %bumble.sroa.0.0.extract.trunc, metadata !18, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !19
+ %bumble.sroa.3.0.extract.shift = lshr i64 %bumble.coerce, 32
+ %bumble.sroa.3.0.extract.trunc = trunc i64 %bumble.sroa.3.0.extract.shift to i32
+ call void @llvm.dbg.value(metadata i32 %bumble.sroa.3.0.extract.trunc, metadata !18, metadata !DIExpression(DW_OP_LLVM_fragment, 32, 32)), !dbg !19
+ store i32 1, i32* @global, align 4, !dbg !20
+ call void @llvm.dbg.value(metadata i32 undef, metadata !21, metadata !DIExpression()), !dbg !19
+ %retval.sroa.2.0.insert.ext = zext i32 %bumble.sroa.3.0.extract.trunc to i64, !dbg !22
+ %retval.sroa.2.0.insert.shift = shl i64 %retval.sroa.2.0.insert.ext, 32, !dbg !22
+ %retval.sroa.0.0.insert.ext = zext i32 %bumble.sroa.0.0.extract.trunc to i64, !dbg !22
+ %retval.sroa.0.0.insert.insert = or i64 %retval.sroa.2.0.insert.shift, %retval.sroa.0.0.insert.ext, !dbg !22
+ ret i64 %retval.sroa.0.0.insert.insert, !dbg !22
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9}
+!llvm.ident = !{!10}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "global", scope: !2, file: !3, line: 6, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 10.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
+!3 = !DIFile(filename: "bees.c", directory: "/")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{!"clang version 10.0.0"}
+!11 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 8, type: !12, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !4)
+!12 = !DISubroutineType(types: !13)
+!13 = !{!14, !14}
+!14 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "bees", file: !3, line: 1, size: 64, elements: !15)
+!15 = !{!16, !17}
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !14, file: !3, line: 2, baseType: !6, size: 32)
+!17 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !14, file: !3, line: 3, baseType: !6, size: 32, offset: 32)
+!18 = !DILocalVariable(name: "bumble", arg: 1, scope: !11, file: !3, line: 8, type: !14)
+!19 = !DILocation(line: 0, scope: !11)
+!20 = !DILocation(line: 10, column: 10, scope: !11)
+!21 = !DILocalVariable(name: "temp", scope: !11, file: !3, line: 11, type: !6)
+!22 = !DILocation(line: 12, column: 3, scope: !11)
diff --git a/llvm/unittests/Transforms/Utils/LocalTest.cpp b/llvm/unittests/Transforms/Utils/LocalTest.cpp
index 1f67a1ec84c..99713d5817f 100644
--- a/llvm/unittests/Transforms/Utils/LocalTest.cpp
+++ b/llvm/unittests/Transforms/Utils/LocalTest.cpp
@@ -759,11 +759,14 @@ TEST(Local, ReplaceAllDbgUsesWith) {
auto *ADbgVal = cast<DbgValueInst>(A.getNextNode());
EXPECT_EQ(ConstantInt::get(A.getType(), 0), ADbgVal->getVariableLocation());
- // Introduce a use-before-def. Check that the dbg.values for %f are deleted.
+ // Introduce a use-before-def. Check that the dbg.values for %f become undef.
EXPECT_TRUE(replaceAllDbgUsesWith(F_, G, G, DT));
+ auto *FDbgVal = cast<DbgValueInst>(F_.getNextNode());
+ EXPECT_TRUE(isa<UndefValue>(FDbgVal->getVariableLocation()));
+
SmallVector<DbgValueInst *, 1> FDbgVals;
- findDbgValues(FDbgVals, &F);
+ findDbgValues(FDbgVals, &F_);
EXPECT_EQ(0U, FDbgVals.size());
// Simulate i32 -> i64 conversion to test sign-extension. Here are some
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