[llvm] [RISCV][GlobalIsel] Reduce constant pool usage without FP extension (PR #158346)

[Shaoce SUN via llvm-commits]

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@@ -1358,7 +1366,12 @@ bool RISCVLegalizerInfo::legalizeCustom(
     return false;
   case TargetOpcode::G_ABS:
     return Helper.lowerAbsToMaxNeg(MI);
-  // TODO: G_FCONSTANT
+  case TargetOpcode::G_FCONSTANT: {
+    const ConstantFP *ConstVal = MI.getOperand(1).getFPImm();
+    if (!shouldBeInFConstantPool(ConstVal->getValue()))
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sunshaoce wrote:

I haven’t figured out how to directly turn `G_FCONSTANT` into a `G_CONSTANT`, so instead I converted `ConstVal->getValue()` with `bitcastToAPInt()`.

https://github.com/llvm/llvm-project/pull/158346