Index: include/llvm/Transforms/Utils/SSAUpdater.h
===================================================================
--- include/llvm/Transforms/Utils/SSAUpdater.h
+++ include/llvm/Transforms/Utils/SSAUpdater.h
@@ -76,6 +76,10 @@
/// block.
bool HasValueForBlock(BasicBlock *BB) const;
+ /// Return the value for the specified block if the SSAUpdater has one,
+ /// otherwise return nullptr.
+ Value *FindValueForBlock(BasicBlock *BB) const;
+
/// Construct SSA form, materializing a value that is live at the end
/// of the specified block.
Value *GetValueAtEndOfBlock(BasicBlock *BB);
Index: include/llvm/Transforms/Utils/SSAUpdaterImpl.h
===================================================================
--- include/llvm/Transforms/Utils/SSAUpdaterImpl.h
+++ include/llvm/Transforms/Utils/SSAUpdaterImpl.h
@@ -357,10 +357,9 @@
BBInfo *Info = *I;
if (Info->DefBB != Info) {
- // Record the available value at join nodes to speed up subsequent
- // uses of this SSAUpdater for the same value.
- if (Info->NumPreds > 1)
- (*AvailableVals)[Info->BB] = Info->DefBB->AvailableVal;
+ // Record the available value to speed up subsequent uses of this
+ // SSAUpdater for the same value.
+ (*AvailableVals)[Info->BB] = Info->DefBB->AvailableVal;
continue;
}
Index: lib/Transforms/Utils/LCSSA.cpp
===================================================================
--- lib/Transforms/Utils/LCSSA.cpp
+++ lib/Transforms/Utils/LCSSA.cpp
@@ -41,6 +41,7 @@
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PredIteratorCache.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils.h"
@@ -113,6 +114,9 @@
if (UsesToRewrite.empty())
continue;
+ SmallVector<DbgValueInst *, 4> DbgValues;
+ llvm::findDbgValues(DbgValues, I);
+
++NumLCSSA; // We are applying the transformation
// Invoke instructions are special in that their result value is not
@@ -201,6 +205,18 @@
SSAUpdate.RewriteUse(*UseToRewrite);
}
+ // Update pre-existing debug value uses that reside outside the loop.
+ auto &Ctx = I->getContext();
+ for (auto DVI : DbgValues) {
+ BasicBlock *UserBB = DVI->getParent();
+ if (InstBB == UserBB || L->contains(UserBB))
+ continue;
+ // We currently only handle debug values residing in blocks where we have
+ // inserted a PHI instruction.
+ if (Value *V = SSAUpdate.FindValueForBlock(UserBB))
+ DVI->setOperand(0, MetadataAsValue::get(Ctx, ValueAsMetadata::get(V)));
+ }
+
// SSAUpdater might have inserted phi-nodes inside other loops. We'll need
// to post-process them to keep LCSSA form.
for (PHINode *InsertedPN : InsertedPHIs) {
Index: lib/Transforms/Utils/SSAUpdater.cpp
===================================================================
--- lib/Transforms/Utils/SSAUpdater.cpp
+++ lib/Transforms/Utils/SSAUpdater.cpp
@@ -64,6 +64,11 @@
return getAvailableVals(AV).count(BB);
}
+Value *SSAUpdater::FindValueForBlock(BasicBlock *BB) const {
+ AvailableValsTy::iterator AVI = getAvailableVals(AV).find(BB);
+ return (AVI != getAvailableVals(AV).end()) ? AVI->second : nullptr;
+}
+
void SSAUpdater::AddAvailableValue(BasicBlock *BB, Value *V) {
assert(ProtoType && "Need to initialize SSAUpdater");
assert(ProtoType == V->getType() &&
Index: test/Transforms/LCSSA/rewrite-existing-dbg-values.ll
===================================================================
--- /dev/null
+++ test/Transforms/LCSSA/rewrite-existing-dbg-values.ll
@@ -0,0 +1,69 @@
+; RUN: opt -S -lcssa < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Reproducer for PR39019.
+;
+; Verify that the llvm.dbg.value in the %for.cond.cleanup2 block is rewritten
+; to use the PHI node for %add that is created by LCSSA.
+
+; CHECK-LABEL: for.cond.cleanup2:
+; CHECK-NEXT: [[PN:%[^ ]*]] = phi i32 [ %add.lcssa, %for.cond.cleanup1 ]
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 [[PN]], metadata [[VAR:![0-9]+]], metadata !DIExpression())
+; CHECK-NEXT: call void @bar(i32 [[PN]])
+
+; CHECK-LABEL: for.body:
+; CHECK: %add = add nsw i32 0, 2
+; CHECK: call void @llvm.dbg.value(metadata i32 %add, metadata [[VAR]], metadata !DIExpression())
+
+; CHECK: [[VAR]] = !DILocalVariable(name: "sum",
+
+; Function Attrs: nounwind
+define void @foo() #0 !dbg !6 {
+entry:
+ br label %for.cond.preheader, !dbg !12
+
+for.cond.preheader: ; preds = %for.cond.cleanup1, %entry
+ br label %for.body, !dbg !12
+
+for.cond.cleanup2: ; preds = %for.cond.cleanup1
+ call void @llvm.dbg.value(metadata i32 %add, metadata !9, metadata !DIExpression()), !dbg !12
+ tail call void @bar(i32 %add) #0, !dbg !12
+ ret void, !dbg !12
+
+for.cond.cleanup1: ; preds = %for.body
+ br i1 false, label %for.cond.preheader, label %for.cond.cleanup2, !dbg !12
+
+for.body: ; preds = %for.body, %for.cond.preheader
+ %add = add nsw i32 0, 2, !dbg !12
+ call void @llvm.dbg.value(metadata i32 %add, metadata !9, metadata !DIExpression()), !dbg !12
+ br i1 false, label %for.body, label %for.cond.cleanup1, !dbg !12
+}
+
+; Function Attrs: nounwind
+declare void @bar(i32) #0
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 8.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !2, nameTableKind: None)
+!1 = !DIFile(filename: "foo.c", directory: "/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 8.0.0"}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 10, type: !7, isLocal: false, isDefinition: true, scopeLine: 10, isOptimized: true, unit: !0, retainedNodes: !8)
+!7 = !DISubroutineType(types: !2)
+!8 = !{!9}
+!9 = !DILocalVariable(name: "sum", scope: !10, file: !1, line: 11, type: !11)
+!10 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 0)
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !DILocation(line: 0, scope: !10)