[llvm] [InstSimplify] Simplify `(fmul -x, +/-0)` -> `-/+0` (PR #85345)

[via llvm-commits]

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@@ -211,6 +211,50 @@ define double @fmul_nnan_ninf_nneg_n0.0_commute(i127 %x) {
   ret double %r
 }
 
+define float @src_mul_nzero_neg(float nofpclass(inf nan pzero psub pnorm) %f) {
+; CHECK-LABEL: @src_mul_nzero_neg(
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %r = fmul float %f, -0.0
+  ret float %r
+}
+
+define <2 x float> @src_mul_zero_neg(<2 x float> nofpclass(inf nan pzero psub pnorm) %f) {
+; CHECK-LABEL: @src_mul_zero_neg(
+; CHECK-NEXT:    ret <2 x float> <float -0.000000e+00, float -0.000000e+00>
+;
+  %r = fmul <2 x float> <float 0.0, float 0.0>, %f
+  ret <2 x float> %r
+}
+
+define <2 x float> @src_mul_zero_and_nzero_neg(<2 x float> nofpclass(inf nan pzero psub pnorm) %f) {
+; CHECK-LABEL: @src_mul_zero_and_nzero_neg(
+; CHECK-NEXT:    ret <2 x float> <float 0.000000e+00, float -0.000000e+00>
+;
+  %r = fmul <2 x float> <float -0.0, float 0.0>, %f
+  ret <2 x float> %r
+}
+
+
+define float @src_muladd_zero_neg(float nofpclass(inf nan pzero psub pnorm) %f, float %add) {
+; CHECK-LABEL: @src_muladd_zero_neg(
+; CHECK-NEXT:    [[R:%.*]] = call float @llvm.fmuladd.f32(float [[F:%.*]], float 0.000000e+00, float [[ADD:%.*]])
+; CHECK-NEXT:    ret float [[R]]
+;
+  %r = call float @llvm.fmuladd.f32(float %f, float 0.0, float %add)
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goldsteinn wrote:

Doesn't seem to be the case, although note `instcombine` does handle the `fmuladd`/`fma`. Just not simplify.

https://github.com/llvm/llvm-project/pull/85345