[llvm] 29817a9 - [X86] Add test coverage for #74101

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2024-08-08T15:10:57+01:00
New Revision: 29817a96262aa96f3e0be632d91ab810e75f728d

URL: https://github.com/llvm/llvm-project/commit/29817a96262aa96f3e0be632d91ab810e75f728d
DIFF: https://github.com/llvm/llvm-project/commit/29817a96262aa96f3e0be632d91ab810e75f728d.diff

LOG: [X86] Add test coverage for #74101

Added: 
    

Modified: 
    llvm/test/CodeGen/X86/combine-sub.ll

Removed: 
    


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diff  --git a/llvm/test/CodeGen/X86/combine-sub.ll b/llvm/test/CodeGen/X86/combine-sub.ll
index 9d5934c345f8a..3123efc306360 100644
--- a/llvm/test/CodeGen/X86/combine-sub.ll
+++ b/llvm/test/CodeGen/X86/combine-sub.ll
@@ -452,3 +452,16 @@ define void @PR52032_4(ptr %p, ptr %q) {
   store <4 x i32> %i9, ptr %p2, align 4
   ret void
 }
+
+; FIXME: Failure to fold add(xor(bsr(x),-32),33) -> add(or(bsr(x),-32),33) -> add(bsr(x),1)
+define i32 @PR74101(i32 %a0) {
+; CHECK-LABEL: PR74101:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    bsrl %edi, %eax
+; CHECK-NEXT:    xorl $-32, %eax
+; CHECK-NEXT:    addl $33, %eax
+; CHECK-NEXT:    retq
+  %lz = call i32 @llvm.ctlz.i32(i32 %a0, i1 true)
+  %add = sub nuw nsw i32 32, %lz
+  ret i32 %add
+}