[llvm] [PowerPC] Fix mask for __st[d/w/h/b]cx builtins (PR #104453)

[Chen Zheng via llvm-commits]

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@@ -26,7 +26,7 @@ define dso_local i64 @test_stdcx(ptr %a, i64 %b) {
 ; CHECK-NEXT:    stdcx. 4, 0, 3
 ; CHECK-NEXT:    mfocrf 3, 128
 ; CHECK-NEXT:    srwi 3, 3, 28
-; CHECK-NEXT:    extsw 3, 3
+; CHECK-NEXT:    srwi 3, 3, 1
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chenzheng1030 wrote:

I created issue https://github.com/llvm/llvm-project/issues/104888 for this combine opportunity.

https://github.com/llvm/llvm-project/pull/104453