| ; RUN: opt -aa-pipeline=basic-aa -passes=aa-eval -print-all-alias-modref-info -disable-output %s 2>&1 | FileCheck %s |
| |
| ; BasicAA must not look through llvm.ptrmask when decomposing a GEP into a |
| ; symbolic byte offset, because ptrmask preserves the underlying object but |
| ; can change the byte address. With %base 2-aligned: |
| ; %p = %base + 1 |
| ; %q = ptrmask(%p, -2) == %base |
| ; %r = %q + 1 == %p |
| ; so %p and %r alias. |
| |
| declare ptr @llvm.ptrmask.p0.i64(ptr, i64) |
| |
| define i8 @ptrmask_gep_may_alias(ptr align 2 %base) { |
| ; CHECK-LABEL: Function: ptrmask_gep_may_alias |
| ; CHECK: MayAlias: i8* %p, i8* %r |
| entry: |
| %p = getelementptr i8, ptr %base, i64 1 |
| %q = call ptr @llvm.ptrmask.p0.i64(ptr %p, i64 -2) |
| %r = getelementptr i8, ptr %q, i64 1 |
| |
| store i8 7, ptr %p, align 1 |
| store i8 42, ptr %r, align 1 |
| %v = load i8, ptr %p, align 1 |
| ret i8 %v |
| } |
