[llvm] [InstCombine] Fold copysign of selects from sign comparison to sign operand (PR #85627)

[Matt Arsenault via llvm-commits]

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@@ -1284,3 +1284,19 @@ define <1 x i1> @bitcast_1vec_eq0(i32 %x) {
   %cmp = fcmp oeq <1 x float> %f, zeroinitializer
   ret <1 x i1> %cmp
 }
+
+define float @copysign_conditional(i1 noundef zeroext %0, float %1, float %2) {
+; CHECK-LABEL: define float @copysign_conditional(
+; CHECK-SAME: i1 noundef zeroext [[TMP0:%.*]], float [[TMP1:%.*]], float [[TMP2:%.*]]) {
+; CHECK-NEXT:    [[TMP4:%.*]] = fcmp olt float [[TMP1]], 0.000000e+00
+; CHECK-NEXT:    [[TMP5:%.*]] = and i1 [[TMP4]], [[TMP0]]
+; CHECK-NEXT:    [[TMP6:%.*]] = select i1 [[TMP5]], float -1.000000e+00, float 1.000000e+00
+; CHECK-NEXT:    [[TMP7:%.*]] = tail call float @llvm.copysign.f32(float [[TMP2]], float [[TMP6]])
+; CHECK-NEXT:    ret float [[TMP7]]
+;
+  %4 = fcmp olt float %1, 0.000000e+00
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arsenm wrote:

Test all the predicate types. And some vectors 

https://github.com/llvm/llvm-project/pull/85627