[llvm] AMDGPU: Disable pattern matching from x&(-1>>(32-y) to "bfe x, 0, y" (PR #116115)

[Changpeng Fang via llvm-commits]

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@@ -99,11 +99,21 @@ define i32 @bzhi32_b4_commutative(i32 %val, i32 %numlowbits) nounwind {
 ; ---------------------------------------------------------------------------- ;
 
 define i32 @bzhi32_c0(i32 %val, i32 %numlowbits) nounwind {
-; GCN-LABEL: bzhi32_c0:
-; GCN:       ; %bb.0:
-; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GCN-NEXT:    v_bfe_u32 v0, v0, 0, v1
-; GCN-NEXT:    s_setpc_b64 s[30:31]
+; SI-LABEL: bzhi32_c0:
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changpeng wrote:

> Run it through instcombine. Whatever it produces is canonical. and computeKnownBits as you did before
Running instcombine like this?
./opt -passes=instcombine canon.ll -S


https://github.com/llvm/llvm-project/pull/116115