[llvm] [GlobalISel] Add constant-folding of FP binops to combiner. (PR #65230)

[Matt Arsenault via llvm-commits]

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@@ -2645,6 +2645,14 @@ void CombinerHelper::replaceInstWithConstant(MachineInstr &MI, APInt C) {
   MI.eraseFromParent();
 }
 
+void CombinerHelper::replaceInstWithFConstant(MachineInstr &MI, ConstantFP *CFP) {
+  assert(MI.getNumDefs() == 1 && "Expected only one def?");
+  APFloat C = CFP->getValueAPF();
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arsenm wrote:

Don't really need this temporary copy 

https://github.com/llvm/llvm-project/pull/65230