[llvm] 721569c - [BasicAA] Add test for benign range overflow (NFC)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2021-10-25T22:09:39+02:00
New Revision: 721569cc36e5d6f80c525bd8f6d53c3d6e7c0efa

URL: https://github.com/llvm/llvm-project/commit/721569cc36e5d6f80c525bd8f6d53c3d6e7c0efa
DIFF: https://github.com/llvm/llvm-project/commit/721569cc36e5d6f80c525bd8f6d53c3d6e7c0efa.diff

LOG: [BasicAA] Add test for benign range overflow (NFC)

Added: 
    

Modified: 
    llvm/test/Analysis/BasicAA/range.ll

Removed: 
    


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diff  --git a/llvm/test/Analysis/BasicAA/range.ll b/llvm/test/Analysis/BasicAA/range.ll
index 78e6add0f50f..6bdb7ccb16e2 100644
--- a/llvm/test/Analysis/BasicAA/range.ll
+++ b/llvm/test/Analysis/BasicAA/range.ll
@@ -196,6 +196,25 @@ define void @multiple(i32* %p, i32* %o1_ptr, i32* %o2_ptr) {
   ret void
 }
 
+; TODO: p.neg1 and p.o.1 don't alias, even though the addition o+1 may overflow.
+; While it makes INT_MIN a possible offset, offset -1 is not possible.
+; CHECK-LABEL: Function: benign_overflow
+; CHECK: MayAlias: i8* %p, i8* %p.o
+; CHECK: MayAlias: i8* %p.neg1, i8* %p.o
+; CHECK: MayAlias: i8* %p, i8* %p.o.1
+; CHECK: MayAlias: i8* %p.neg1, i8* %p.o.1
+; CHECK: NoAlias:  i8* %p.o, i8* %p.o.1
+define void @benign_overflow(i8* %p, i64 %o) {
+  %c = icmp sge i64 %o, -1
+  call void @llvm.assume(i1 %c)
+  %p.neg1 = getelementptr i8, i8* %p, i64 -1
+  %p.o = getelementptr i8, i8* %p, i64 %o
+  %p.o.1 = getelementptr i8, i8* %p.o, i64 1
+  ret void
+}
+
+declare void @llvm.assume(i1)
+
 
 !0 = !{ i32 0, i32 2 }
 !1 = !{ i32 0, i32 1 }