[llvm] [SystemZ] Support pseudo fmin/fmax (PR #209178)

[Nikita Popov via llvm-commits]

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@@ -61,7 +61,7 @@ define double @f4(double %dummy, double %val) {
 ; CHECK-LABEL: f4:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    lzdr %f0
-; CHECK-NEXT:    wfmindb %f0, %f2, %f0, 4
+; CHECK-NEXT:    wfmindb %f0, %f2, %f0, 2
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nikic wrote:

This was previously miscompiled. If %val=-0.0 then the IR would return 0.0, but wfmindb 4 would return -0.0 (I believe), while wfmindb 2 should correctly return 0.0.

(This is due to a bug in ValueTracking.)

https://github.com/llvm/llvm-project/pull/209178