[llvm] [GlobalISel] replace right identity X * -1.0 with fneg(x) (PR #80526)

[Phoebe Wang via llvm-commits]

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@@ -43,6 +43,7 @@ define i8 @cnt8(i8 %x) nounwind readnone {
 ; X64-POPCNT-NEXT:    popcntl %eax, %eax
 ; X64-POPCNT-NEXT:    # kill: def $al killed $al killed $eax
 ; X64-POPCNT-NEXT:    retq
+
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phoebewang wrote:

The change seems unrelated, should better to revert.

https://github.com/llvm/llvm-project/pull/80526