[KeyInstr][SimplifyCFG] Remap atoms after duplication for threading #133484
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This was referenced Mar 28, 2025
This was referenced Mar 28, 2025
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@llvm/pr-subscribers-llvm-transforms Author: Orlando Cazalet-Hyams (OCHyams) ChangesGiven the same branch condition in --> a --> c --> e --> into: --> a --> c --> e --> Remap source atoms on instructions duplicated from Full diff: https://github.com/llvm/llvm-project/pull/133484.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 1ba1e4ac81000..c83ff0260e297 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -3589,7 +3589,7 @@ foldCondBranchOnValueKnownInPredecessorImpl(BranchInst *BI, DomTreeUpdater *DTU,
// instructions into EdgeBB. We know that there will be no uses of the
// cloned instructions outside of EdgeBB.
BasicBlock::iterator InsertPt = EdgeBB->getFirstInsertionPt();
- DenseMap<Value *, Value *> TranslateMap; // Track translated values.
+ ValueToValueMapTy TranslateMap; // Track translated values.
TranslateMap[Cond] = CB;
// RemoveDIs: track instructions that we optimise away while folding, so
@@ -3609,11 +3609,11 @@ foldCondBranchOnValueKnownInPredecessorImpl(BranchInst *BI, DomTreeUpdater *DTU,
N->setName(BBI->getName() + ".c");
// Update operands due to translation.
- for (Use &Op : N->operands()) {
- DenseMap<Value *, Value *>::iterator PI = TranslateMap.find(Op);
- if (PI != TranslateMap.end())
- Op = PI->second;
- }
+ // Key Instructions: Remap all the atom groups.
+ if (const DebugLoc &DL = BBI->getDebugLoc())
+ mapAtomInstance(DL, TranslateMap);
+ RemapInstruction(N, TranslateMap,
+ RF_IgnoreMissingLocals | RF_NoModuleLevelChanges);
// Check for trivial simplification.
if (Value *V = simplifyInstruction(N, {DL, nullptr, nullptr, AC})) {
diff --git a/llvm/test/DebugInfo/KeyInstructions/Generic/simplifycfg-thread-phi.ll b/llvm/test/DebugInfo/KeyInstructions/Generic/simplifycfg-thread-phi.ll
new file mode 100644
index 0000000000000..f8477600c6418
--- /dev/null
+++ b/llvm/test/DebugInfo/KeyInstructions/Generic/simplifycfg-thread-phi.ll
@@ -0,0 +1,62 @@
+; RUN: opt %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S \
+; RUN: | FileCheck %s
+
+;; Generated using:
+;; opt -passes=debugify --debugify-atoms --debugify-level=locations \
+;; llvm/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll
+;; With unused/untested metadata nodes removed.
+
+;; Check the duplicated store gets distinct atom info in each branch.
+
+; CHECK-LABEL: @bar(
+; CHECK: if.then:
+; CHECK: store i32 1{{.*}}, !dbg [[DBG1:!.*]]
+; CHECK: if.end.1.critedge:
+; CHECK: store i32 1{{.*}}, !dbg [[DBG2:!.*]]
+; CHECK: [[DBG1]] = !DILocation(line: 1{{.*}}, atomGroup: 1
+; CHECK: [[DBG2]] = !DILocation(line: 1{{.*}}, atomGroup: 2
+
+define void @bar(i32 %aa) !dbg !5 {
+entry:
+ %aa.addr = alloca i32, align 4
+ %bb = alloca i32, align 4
+ store i32 %aa, ptr %aa.addr, align 4
+ store i32 0, ptr %bb, align 4
+ %tobool = icmp ne i32 %aa, 0
+ br i1 %tobool, label %if.then, label %if.end
+
+if.then: ; preds = %entry
+ call void @foo()
+ br label %if.end
+
+if.end: ; preds = %if.then, %entry
+ store i32 1, ptr %bb, align 4, !dbg !8
+ br i1 %tobool, label %if.then.1, label %if.end.1
+
+if.then.1: ; preds = %if.end
+ call void @foo()
+ br label %if.end.1
+
+if.end.1: ; preds = %if.then.1, %if.end
+ store i32 2, ptr %bb, align 4
+ br label %for.end
+
+for.end: ; preds = %if.end.1
+ ret void
+}
+
+declare void @foo()
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!2, !3}
+!llvm.module.flags = !{!4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+!1 = !DIFile(filename: "llvm/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll", directory: "/")
+!2 = !{i32 15}
+!3 = !{i32 0}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "bar", linkageName: "bar", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !DILocation(line: 1, column: 1, scope: !5, atomGroup: 1, atomRank: 1)
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@llvm/pr-subscribers-debuginfo Author: Orlando Cazalet-Hyams (OCHyams) ChangesGiven the same branch condition in --> a --> c --> e --> into: --> a --> c --> e --> Remap source atoms on instructions duplicated from Full diff: https://github.com/llvm/llvm-project/pull/133484.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 1ba1e4ac81000..c83ff0260e297 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -3589,7 +3589,7 @@ foldCondBranchOnValueKnownInPredecessorImpl(BranchInst *BI, DomTreeUpdater *DTU,
// instructions into EdgeBB. We know that there will be no uses of the
// cloned instructions outside of EdgeBB.
BasicBlock::iterator InsertPt = EdgeBB->getFirstInsertionPt();
- DenseMap<Value *, Value *> TranslateMap; // Track translated values.
+ ValueToValueMapTy TranslateMap; // Track translated values.
TranslateMap[Cond] = CB;
// RemoveDIs: track instructions that we optimise away while folding, so
@@ -3609,11 +3609,11 @@ foldCondBranchOnValueKnownInPredecessorImpl(BranchInst *BI, DomTreeUpdater *DTU,
N->setName(BBI->getName() + ".c");
// Update operands due to translation.
- for (Use &Op : N->operands()) {
- DenseMap<Value *, Value *>::iterator PI = TranslateMap.find(Op);
- if (PI != TranslateMap.end())
- Op = PI->second;
- }
+ // Key Instructions: Remap all the atom groups.
+ if (const DebugLoc &DL = BBI->getDebugLoc())
+ mapAtomInstance(DL, TranslateMap);
+ RemapInstruction(N, TranslateMap,
+ RF_IgnoreMissingLocals | RF_NoModuleLevelChanges);
// Check for trivial simplification.
if (Value *V = simplifyInstruction(N, {DL, nullptr, nullptr, AC})) {
diff --git a/llvm/test/DebugInfo/KeyInstructions/Generic/simplifycfg-thread-phi.ll b/llvm/test/DebugInfo/KeyInstructions/Generic/simplifycfg-thread-phi.ll
new file mode 100644
index 0000000000000..f8477600c6418
--- /dev/null
+++ b/llvm/test/DebugInfo/KeyInstructions/Generic/simplifycfg-thread-phi.ll
@@ -0,0 +1,62 @@
+; RUN: opt %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S \
+; RUN: | FileCheck %s
+
+;; Generated using:
+;; opt -passes=debugify --debugify-atoms --debugify-level=locations \
+;; llvm/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll
+;; With unused/untested metadata nodes removed.
+
+;; Check the duplicated store gets distinct atom info in each branch.
+
+; CHECK-LABEL: @bar(
+; CHECK: if.then:
+; CHECK: store i32 1{{.*}}, !dbg [[DBG1:!.*]]
+; CHECK: if.end.1.critedge:
+; CHECK: store i32 1{{.*}}, !dbg [[DBG2:!.*]]
+; CHECK: [[DBG1]] = !DILocation(line: 1{{.*}}, atomGroup: 1
+; CHECK: [[DBG2]] = !DILocation(line: 1{{.*}}, atomGroup: 2
+
+define void @bar(i32 %aa) !dbg !5 {
+entry:
+ %aa.addr = alloca i32, align 4
+ %bb = alloca i32, align 4
+ store i32 %aa, ptr %aa.addr, align 4
+ store i32 0, ptr %bb, align 4
+ %tobool = icmp ne i32 %aa, 0
+ br i1 %tobool, label %if.then, label %if.end
+
+if.then: ; preds = %entry
+ call void @foo()
+ br label %if.end
+
+if.end: ; preds = %if.then, %entry
+ store i32 1, ptr %bb, align 4, !dbg !8
+ br i1 %tobool, label %if.then.1, label %if.end.1
+
+if.then.1: ; preds = %if.end
+ call void @foo()
+ br label %if.end.1
+
+if.end.1: ; preds = %if.then.1, %if.end
+ store i32 2, ptr %bb, align 4
+ br label %for.end
+
+for.end: ; preds = %if.end.1
+ ret void
+}
+
+declare void @foo()
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!2, !3}
+!llvm.module.flags = !{!4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+!1 = !DIFile(filename: "llvm/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll", directory: "/")
+!2 = !{i32 15}
+!3 = !{i32 0}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "bar", linkageName: "bar", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !DILocation(line: 1, column: 1, scope: !5, atomGroup: 1, atomRank: 1)
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This was referenced Apr 7, 2025
This was referenced Apr 7, 2025
SLTozer
reviewed
Apr 9, 2025
Comment on lines
+3615
to
+3617
| RemapInstruction(N, TranslateMap, | ||
| RF_IgnoreMissingLocals | RF_NoModuleLevelChanges); |
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If I understand right, RemapInstruction with these operands and no materializer will never create a new value mapping, only ever return an existing mapping - is that correct?
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Yeah that should be the case here.
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Given the same branch condition in `a` and `c` SimplifyCFG converts:
+> b -+
| v
--> a --> c --> e -->
| ^
+> d -+
into:
+--> bcd ---+
| v
--> a --> c --> e -->
Remap source atoms on instructions duplicated from `c` into `bcd`.
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GeorgeARM
pushed a commit
to GeorgeARM/llvm-project
that referenced
this pull request
May 7, 2025
…lvm#133484) Given the same branch condition in `a` and `c` SimplifyCFG converts: +> b -+ | v --> a --> c --> e --> | ^ +> d -+ into: +--> bcd ---+ | v --> a --> c --> e --> Remap source atoms on instructions duplicated from `c` into `bcd`. RFC: https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668
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Given the same branch condition in
aandcSimplifyCFG converts:into:
Remap source atoms on instructions duplicated from
cintobcd.