[llvm] [X86] Don't always separate conditions in `(br (and/or cond0, cond1))` into separate branches (PR #81689)

[Simon Pilgrim via llvm-commits]

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@@ -18,11 +18,13 @@ define void @test_dec_select(ptr nocapture %0, ptr readnone %1) {
 ; CHECK-LABEL: test_dec_select:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    lock decq (%rdi)
-; CHECK-NEXT:    jne .LBB0_2
-; CHECK-NEXT:  # %bb.1:
+; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    testq %rsi, %rsi
-; CHECK-NEXT:    jne func2 # TAILCALL
-; CHECK-NEXT:  .LBB0_2:
+; CHECK-NEXT:    setne %cl
+; CHECK-NEXT:    andb %al, %cl
+; CHECK-NEXT:    cmpb $1, %cl
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RKSimon wrote:

Any idea why the and+cmp hasn't folded to test? Not related to this patch but maybe worth a followup investigation?

https://github.com/llvm/llvm-project/pull/81689