[llvm] 9863725 - [DA] Add test for the Exact test misses dependency due to overflow (NFC) (#200780)

[via llvm-commits]

Author: Ryotaro Kasuga
Date: 2026-06-01T11:24:04Z
New Revision: 9863725ffe80054d3fb86d7468746a1d0def26c4

URL: https://github.com/llvm/llvm-project/commit/9863725ffe80054d3fb86d7468746a1d0def26c4
DIFF: https://github.com/llvm/llvm-project/commit/9863725ffe80054d3fb86d7468746a1d0def26c4.diff

LOG: [DA] Add test for the Exact test misses dependency due to overflow (NFC) (#200780)

This patch adds a test case that demonstrates that the Exact test misses
the dependency due to mishandling of overflow. The test case is taken
from #200766.

Added: 
    llvm/test/Analysis/DependenceAnalysis/exact-siv-mul-overflow.ll

Modified: 
    

Removed: 
    


################################################################################
diff  --git a/llvm/test/Analysis/DependenceAnalysis/exact-siv-mul-overflow.ll b/llvm/test/Analysis/DependenceAnalysis/exact-siv-mul-overflow.ll
new file mode 100644
index 0000000000000..92e1f9ac565fd
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/exact-siv-mul-overflow.ll
@@ -0,0 +1,54 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6
+; RUN: opt < %s -disable-output "-passes=print<da>" 2>&1 \
+; RUN:     | FileCheck %s --check-prefixes=CHECK,CHECK-ALL
+; RUN: opt < %s -disable-output "-passes=print<da>" -da-enable-dependence-test=exact-siv 2>&1 \
+; RUN:     | FileCheck %s --check-prefixes=CHECK,CHECK-EXACT-SIV
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32-S128"
+
+; for (i = 0; i < 160000000; i++) {
+;   A[5*i] = 0;
+;   A[8*i + 750000000] = 1;
+; }
+;
+; There is a dependency between the two accesses, for example,
+;
+;  memory access     | i = 0         | i = 150000000
+; -------------------|---------------|---------------
+;  A[5*i]            |               | A[750000000]
+;  A[8*i + 750000000]| A[750000000]  |
+;
+; FIXME: DependenceAnalysis currently fails to detect this dependency due to
+; mishandling of overflow.
+;
+define void @exactsiv_mul_overflow(ptr %A) {
+; CHECK-LABEL: 'exactsiv_mul_overflow'
+; CHECK-NEXT:  Src: store i8 0, ptr %src.ptr, align 1 --> Dst: store i8 0, ptr %src.ptr, align 1
+; CHECK-NEXT:    da analyze - none!
+; CHECK-NEXT:  Src: store i8 0, ptr %src.ptr, align 1 --> Dst: store i8 1, ptr %dst.ptr, align 1
+; CHECK-NEXT:    da analyze - none!
+; CHECK-NEXT:  Src: store i8 1, ptr %dst.ptr, align 1 --> Dst: store i8 1, ptr %dst.ptr, align 1
+; CHECK-NEXT:    da analyze - none!
+;
+entry:
+  br label %loop
+
+loop:
+  %i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
+  %src.idx = mul nsw i32 %i, 5
+  %src.ptr = getelementptr inbounds i8, ptr %A, i32 %src.idx
+  store i8 0, ptr %src.ptr
+  %dst.idx.1 = mul nsw i32 %i, 8
+  %dst.idx = add nsw i32 %dst.idx.1, 750000000
+  %dst.ptr = getelementptr inbounds i8, ptr %A, i32 %dst.idx
+  store i8 1, ptr %dst.ptr
+  %i.next = add nsw i32 %i, 1
+  %ec = icmp eq i32 %i.next, 160000000
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; CHECK-ALL: {{.*}}
+; CHECK-EXACT-SIV: {{.*}}