[llvm] [APFloat] Add `APFloat::getConstant` for C++20 <numbers> constants (PR #227916)

[Eric Ross via llvm-commits]

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@@ -2829,8 +2829,11 @@ Value *LibCallSimplifier::optimizeLog(CallInst *Log, IRBuilderBase &B) {
            ArgID == Intrinsic::exp || ArgID == Intrinsic::exp2) {
     Constant *Eul;
     if (ArgLb == ExpLb || ArgID == Intrinsic::exp)
-      // FIXME: Add more precise value of e for long double.
-      Eul = ConstantFP::get(Log->getType(), numbers::e);
+      Eul = ConstantFP::get(
+          Log->getType(),
+          APFloat::getConstant(
+              APFloat::MathConstant::e,
+              Log->getType()->getScalarType()->getFltSemantics()));
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ZERICO2005 wrote:

Should we add `ConstantFP::getConstant`?

https://github.com/llvm/llvm-project/pull/227916