[llvm] [X86] LowerSelect - generalize "select icmp(x,0), lhs, rhs" folding patterns. (PR #107272)

[Phoebe Wang via llvm-commits]

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@@ -77,12 +77,11 @@ define i32 @or_signbit_select_shl(i32 %x, i1 %cond, ptr %dst) {
 ; X86-LABEL: or_signbit_select_shl:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT:    testb $1, {{[0-9]+}}(%esp)
-; X86-NEXT:    je .LBB2_2
-; X86-NEXT:  # %bb.1:
-; X86-NEXT:    orl $16711680, %eax # imm = 0xFF0000
-; X86-NEXT:  .LBB2_2:
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %eax
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phoebewang wrote:

Comparing with above X64 instructions, it looks here is slight slightly better. Should we do it for 64-bit too (maybe due to hasCMOV)?

https://github.com/llvm/llvm-project/pull/107272