[llvm] [DA] Fix crash when two loops have different type sizes of becount (PR #165021)
Shimin Cui via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 27 06:55:04 PDT 2025
https://github.com/scui-ibm updated https://github.com/llvm/llvm-project/pull/165021
>From 88940744fe558e2efddc5afc8832f35635f7489d Mon Sep 17 00:00:00 2001
From: Shimin Cui <scui at xlperflep9.rtp.raleigh.ibm.com>
Date: Fri, 24 Oct 2025 17:30:10 +0000
Subject: [PATCH 1/2] [DA] Fix for different sizes of loop becount types in
haveSameSD
---
llvm/lib/Analysis/DependenceAnalysis.cpp | 15 +++-
.../same-sd-for-diff-becount-type-loops.ll | 68 +++++++++++++++++++
2 files changed, 80 insertions(+), 3 deletions(-)
create mode 100644 llvm/test/Analysis/DependenceAnalysis/same-sd-for-diff-becount-type-loops.ll
diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index a572eefddd20e..3e9b9ee77640f 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -1131,9 +1131,18 @@ bool DependenceInfo::haveSameSD(const Loop *SrcLoop,
if (SE->hasLoopInvariantBackedgeTakenCount(DstLoop))
DstUP = SE->getBackedgeTakenCount(DstLoop);
- if (SrcUB != nullptr && DstUP != nullptr &&
- SE->isKnownPredicate(ICmpInst::ICMP_EQ, SrcUB, DstUP))
- return true;
+ if (SrcUB != nullptr && DstUP != nullptr) {
+ unsigned SrcBitWidth = SE->getTypeSizeInBits(SrcUB->getType());
+ unsigned DstBitWidth = SE->getTypeSizeInBits(DstUP->getType());
+ if (SrcBitWidth < DstBitWidth) {
+ SrcUB = SE->getZeroExtendExpr(SrcUB, DstUP->getType());
+ } else if (SrcBitWidth > DstBitWidth) {
+ DstUP = SE->getZeroExtendExpr(DstUP, SrcUB->getType());
+ }
+
+ if (SE->isKnownPredicate(ICmpInst::ICMP_EQ, SrcUB, DstUP))
+ return true;
+ }
return false;
}
diff --git a/llvm/test/Analysis/DependenceAnalysis/same-sd-for-diff-becount-type-loops.ll b/llvm/test/Analysis/DependenceAnalysis/same-sd-for-diff-becount-type-loops.ll
new file mode 100644
index 0000000000000..66880b5a553ec
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/same-sd-for-diff-becount-type-loops.ll
@@ -0,0 +1,68 @@
+; RUN: opt < %s -disable-output "-passes=print<da>" -aa-pipeline=basic-aa 2>&1 | FileCheck %s
+
+define void @f1() {
+; CHECK-LABEL: 'f1'
+; CHECK-NEXT: Src: store i32 0, ptr null, align 4 --> Dst: store i32 0, ptr null, align 4
+; CHECK-NEXT: da analyze - consistent output [S]!
+; CHECK-NEXT: Src: store i32 0, ptr null, align 4 --> Dst: %2 = load i32, ptr null, align 4
+; CHECK-NEXT: da analyze - consistent flow [|<]!
+; CHECK-NEXT: Src: %2 = load i32, ptr null, align 4 --> Dst: %2 = load i32, ptr null, align 4
+; CHECK-NEXT: da analyze - consistent input [S]!
+;
+entry:
+ br label %for.1.header
+
+for.1.header: ; preds = %for.2.end, %entry
+ br label %for.1.body
+
+for.1.body: ; preds = %for.1.body, %whiledo
+ %0 = phi i32 [ 0, %for.1.header ], [ 1, %for.1.body ]
+ store i32 0, ptr null, align 4
+ %1 = icmp ult i32 %0, 1
+ br i1 %1, label %for.1.body, label %for.1.end
+
+for.1.end: ; preds = %for.1.body
+ br label %for.2.body
+
+for.2.body: ; preds = %for.2.body, %for.1.end
+ %2 = load i32, ptr null, align 4
+ br i1 false, label %for.2.body, label %exit
+
+exit: ; preds = %for.2.body
+ ret void
+}
+
+define void @f2() {
+; CHECK-LABEL: 'f2'
+; CHECK-NEXT: Src: store i32 0, ptr null, align 4 --> Dst: store i32 0, ptr null, align 4
+; CHECK-NEXT: da analyze - consistent output [S]!
+; CHECK-NEXT: Src: store i32 0, ptr null, align 4 --> Dst: %3 = load i32, ptr null, align 4
+; CHECK-NEXT: da analyze - flow [|<] / assuming 1 loop level(s) fused: [S|<]!
+; CHECK-NEXT: Src: %3 = load i32, ptr null, align 4 --> Dst: %3 = load i32, ptr null, align 4
+; CHECK-NEXT: da analyze - consistent input [S]!
+;
+entry:
+ br label %for.1.header
+
+for.1.header: ; preds = %for.2.end, %entry
+ br label %for.1.body
+
+for.1.body: ; preds = %for.1.body, %whiledo
+ %0 = phi i32 [ 0, %for.1.header ], [ 1, %for.1.body ]
+ store i32 0, ptr null, align 4
+ %1 = icmp ult i32 %0, 1
+ br i1 %1, label %for.1.body, label %for.1.end
+
+for.1.end: ; preds = %for.1.body
+ br label %for.2.body
+
+for.2.body: ; preds = %for.2.body, %for.1.end
+ %2 = phi i64 [ 0, %for.1.end ], [ %4, %for.2.body ]
+ %3 = load i32, ptr null, align 4
+ %4 = add nuw nsw i64 %2, 1
+ %5 = icmp ult i64 %4, 2
+ br i1 %5, label %for.2.body, label %exit
+
+exit: ; preds = %for.2.body
+ ret void
+}
>From 8f2a40d3457e6e81d6afd0fc5929eb3dc2a55e78 Mon Sep 17 00:00:00 2001
From: Shimin Cui <scui at xlperflep9.rtp.raleigh.ibm.com>
Date: Mon, 27 Oct 2025 13:50:15 +0000
Subject: [PATCH 2/2] Use SE.getWiderType&getNoopOrZeroExtend per Florian's
suggestion
---
llvm/lib/Analysis/DependenceAnalysis.cpp | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 3e9b9ee77640f..84ee8c0bf3e18 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -1132,13 +1132,9 @@ bool DependenceInfo::haveSameSD(const Loop *SrcLoop,
DstUP = SE->getBackedgeTakenCount(DstLoop);
if (SrcUB != nullptr && DstUP != nullptr) {
- unsigned SrcBitWidth = SE->getTypeSizeInBits(SrcUB->getType());
- unsigned DstBitWidth = SE->getTypeSizeInBits(DstUP->getType());
- if (SrcBitWidth < DstBitWidth) {
- SrcUB = SE->getZeroExtendExpr(SrcUB, DstUP->getType());
- } else if (SrcBitWidth > DstBitWidth) {
- DstUP = SE->getZeroExtendExpr(DstUP, SrcUB->getType());
- }
+ Type *WiderType = SE->getWiderType(SrcUB->getType(), DstUP->getType());
+ SrcUB = SE->getNoopOrZeroExtend(SrcUB, WiderType);
+ DstUP = SE->getNoopOrZeroExtend(DstUP, WiderType);
if (SE->isKnownPredicate(ICmpInst::ICMP_EQ, SrcUB, DstUP))
return true;
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