[llvm] [DAGCombiner] Freeze maybe poison operands when folding select to logic (PR #84924)

[Matt Arsenault via llvm-commits]

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@@ -295,22 +295,28 @@ define float @select_icmp_sle(i32 %x, i32 %y, float %a, float %b) {
 ; Test peephole optimizations for select.
 define zeroext i1 @select_opt1(i1 zeroext %c, i1 zeroext %a) {
 ; CHECK-LABEL: select_opt1
-; CHECK:       orr {{w[0-9]+}}, w0, w1
+; SISEL:       orr [[REG:w[0-9]+]], w0, w1
+; SISEL:       and w0, [[REG]], #0x1
+; FISEL:       orr {{w[0-9]+}}, w0, w1
   %1 = select i1 %c, i1 true, i1 %a
   ret i1 %1
 }
 
 define zeroext i1 @select_opt2(i1 zeroext %c, i1 zeroext %a) {
 ; CHECK-LABEL: select_opt2
-; CHECK:       eor [[REG:w[0-9]+]], w0, #0x1
-; CHECK:       orr {{w[0-9]+}}, [[REG]], w1
+; SISEL:       orn [[REG:w[0-9]+]], w1, w0
+; SISEL:       and w0, [[REG]], #0x1
+; FISEL:       eor [[REG:w[0-9]+]], w0, #0x1
+; FISEL:       orr {{w[0-9]+}}, [[REG]], w1
   %1 = select i1 %c, i1 %a, i1 true
   ret i1 %1
 }
 
 define zeroext i1 @select_opt3(i1 zeroext %c, i1 zeroext %a) {
 ; CHECK-LABEL: select_opt3
-; CHECK:       bic {{w[0-9]+}}, w1, w0
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arsenm wrote:

I guess we should have an equivalent AssertNoundef or something, but the intersection of all the Assert*s corresponding to argument attributes is not great 

https://github.com/llvm/llvm-project/pull/84924