[llvm] [IRBuilder] Fold binary intrinsics (PR #80743)

[Simon Pilgrim via llvm-commits]

================
@@ -14116,28 +14116,12 @@ class HorizontalReduction {
       return Builder.CreateBinOp((Instruction::BinaryOps)RdxOpcode, LHS, RHS,
                                  Name);
     case RecurKind::FMax:
-      if (IsConstant)
-        return ConstantFP::get(LHS->getType(),
-                               maxnum(cast<ConstantFP>(LHS)->getValueAPF(),
-                                      cast<ConstantFP>(RHS)->getValueAPF()));
       return Builder.CreateBinaryIntrinsic(Intrinsic::maxnum, LHS, RHS);
     case RecurKind::FMin:
-      if (IsConstant)
-        return ConstantFP::get(LHS->getType(),
-                               minnum(cast<ConstantFP>(LHS)->getValueAPF(),
-                                      cast<ConstantFP>(RHS)->getValueAPF()));
       return Builder.CreateBinaryIntrinsic(Intrinsic::minnum, LHS, RHS);
     case RecurKind::FMaximum:
-      if (IsConstant)
-        return ConstantFP::get(LHS->getType(),
-                               maximum(cast<ConstantFP>(LHS)->getValueAPF(),
-                                      cast<ConstantFP>(RHS)->getValueAPF()));
       return Builder.CreateBinaryIntrinsic(Intrinsic::maximum, LHS, RHS);
     case RecurKind::FMinimum:
-      if (IsConstant)
-        return ConstantFP::get(LHS->getType(),
-                               minimum(cast<ConstantFP>(LHS)->getValueAPF(),
-                                      cast<ConstantFP>(RHS)->getValueAPF()));
       return Builder.CreateBinaryIntrinsic(Intrinsic::minimum, LHS, RHS);
----------------
RKSimon wrote:

You should now be able to merge these and use getMinMaxReductionIntrinsicOp(Kind) to get the Intrinsic::ID
```cpp
case RecurKind::FMax:
case RecurKind::FMin:
case RecurKind::FMaximum:
case RecurKind::FMinimum:
  return Builder.CreateBinaryIntrinsic(getMinMaxReductionIntrinsicOp(Kind), LHS, RHS);
```

https://github.com/llvm/llvm-project/pull/80743