[llvm] [Mips] Add lowerConstantFP to optimize some floating load instrs to mtc1+mthc1 (PR #196226)

[Jiaxun Yang via llvm-commits]

================
@@ -272,6 +273,9 @@ MipsTargetLowering::MipsTargetLowering(const MipsTargetMachine &TM,
     setOperationAction(ISD::FCANONICALIZE, MVT::f64, Custom);
   }
 
+  if (Subtarget.hasMips32r2())
----------------
FlyGoat wrote:

`hasMTHC1()`

https://github.com/llvm/llvm-project/pull/196226