[llvm] 804ece6 - [DA] Require `nsw` for AddRecs in the WeakCrossing SIV test (#185041)

[via llvm-commits]

Author: Ehsan Amiri
Date: 2026-03-30T15:51:44-04:00
New Revision: 804ece6a4ff0a971b142f83ebcd45a9c9625aae5

URL: https://github.com/llvm/llvm-project/commit/804ece6a4ff0a971b142f83ebcd45a9c9625aae5
DIFF: https://github.com/llvm/llvm-project/commit/804ece6a4ff0a971b142f83ebcd45a9c9625aae5.diff

LOG: [DA] Require `nsw` for AddRecs in the WeakCrossing SIV test (#185041)

Before the start of the algorithm in weak crossing SIV test, we need to
ensure both addrecs are `nsw`

Added: 
    

Modified: 
    llvm/lib/Analysis/DependenceAnalysis.cpp
    llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll
    llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-addrec-wrap.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index e7cfc17f8eb00..c9371f39c0e18 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -1370,6 +1370,9 @@ bool DependenceInfo::weakCrossingSIVtest(const SCEVAddRecExpr *Src,
   if (!isDependenceTestEnabled(DependenceTestType::WeakCrossingSIV))
     return false;
 
+  if (!Src->hasNoSignedWrap() || !Dst->hasNoSignedWrap())
+    return false;
+
   const SCEV *Coeff = Src->getStepRecurrence(*SE);
   const SCEV *SrcConst = Src->getStart();
   const SCEV *DstConst = Dst->getStart();

diff  --git a/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll b/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll
index 13d2b61d2ab91..38d254edb79db 100644
--- a/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll
+++ b/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll
@@ -68,7 +68,7 @@ define void @weakcrossing1(ptr %A, ptr %B, i64 %n) nounwind uwtable ssp {
 ; CHECK-NEXT:  Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %conv, ptr %arrayidx, align 4
 ; CHECK-NEXT:    da analyze - output [*]!
 ; CHECK-NEXT:  Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: %0 = load i32, ptr %arrayidx2, align 4
-; CHECK-NEXT:    da analyze - flow [<>]!
+; CHECK-NEXT:    da analyze - flow [*|<]!
 ; CHECK-NEXT:  Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %0, ptr %B.addr.02, align 4
 ; CHECK-NEXT:    da analyze - confused!
 ; CHECK-NEXT:  Src: %0 = load i32, ptr %arrayidx2, align 4 --> Dst: %0 = load i32, ptr %arrayidx2, align 4
@@ -245,7 +245,7 @@ define void @weakcrossing5(ptr %A, ptr %B, i64 %n) nounwind uwtable ssp {
 ; CHECK-NEXT:  Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %conv, ptr %arrayidx, align 4
 ; CHECK-NEXT:    da analyze - output [*]!
 ; CHECK-NEXT:  Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: %1 = load i32, ptr %arrayidx2, align 4
-; CHECK-NEXT:    da analyze - none!
+; CHECK-NEXT:    da analyze - flow [*|<]!
 ; CHECK-NEXT:  Src: store i32 %conv, ptr %arrayidx, align 4 --> Dst: store i32 %1, ptr %B.addr.02, align 4
 ; CHECK-NEXT:    da analyze - confused!
 ; CHECK-NEXT:  Src: %1 = load i32, ptr %arrayidx2, align 4 --> Dst: %1 = load i32, ptr %arrayidx2, align 4

diff  --git a/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-addrec-wrap.ll b/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-addrec-wrap.ll
index 850f844a53df7..93f2b4e5877f5 100644
--- a/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-addrec-wrap.ll
+++ b/llvm/test/Analysis/DependenceAnalysis/weak-crossing-siv-addrec-wrap.ll
@@ -20,15 +20,13 @@
 ;  A[(2^62+1)*i]      | A[0]   | A[4]
 ;  A[-(2^62+1)*i + 4] | A[4]   | A[0]
 ;
-; FIXME: DependenceAnalysis fails to detect the dependency between the two
-; stores.
 ;
 define void @weak_crossing_siv_no_nsw(ptr %A) {
 ; CHECK-LABEL: 'weak_crossing_siv_no_nsw'
 ; CHECK-NEXT:  Src: store i8 0, ptr %gep.0, align 1 --> Dst: store i8 0, ptr %gep.0, align 1
 ; CHECK-NEXT:    da analyze - output [*]!
 ; CHECK-NEXT:  Src: store i8 0, ptr %gep.0, align 1 --> Dst: store i8 1, ptr %gep.1, align 1
-; CHECK-NEXT:    da analyze - none!
+; CHECK-NEXT:    da analyze - output [*|<]!
 ; CHECK-NEXT:  Src: store i8 1, ptr %gep.1, align 1 --> Dst: store i8 1, ptr %gep.1, align 1
 ; CHECK-NEXT:    da analyze - output [*]!
 ;