[FLANG][NFCI]De-duplicate code in SimplifyIntrinsics

[Leporacanthicus]

Summary

This removes a bunch of duplicated code, by adding an intermediate
function simplifyReduction that takes a std::function argument
for the actual replacement of the code.

No functional change intended.

[Leporacanthicus]

Updated comment for helper function

[vzakhari]

flang/lib/Optimizer/Transforms/SimplifyIntrinsics.cpp

58

I was recently told that we do not usually use std::function. The advice was to replace it with function_ref: https://reviews.llvm.org/D129810#inline-1277689

80

typo: hte

81

typo? simplifyd -> simplified or simplify?

[Leporacanthicus]

Updates per review comments:

• Fix typos
• Use llvm::function_ref instead of std::function

[vzakhari]

Thanks for function_ref replacements!

flang/lib/Optimizer/Transforms/SimplifyIntrinsics.cpp

81

[Leporacanthicus]

flang/lib/Optimizer/Transforms/SimplifyIntrinsics.cpp

58

Ok, there's only 5 in this section of code, I will fix those.

There's 115 std::function and 10 llvm::function_ref in flang - not making excuses here, but I think a separate cleanup patch may be required.

I will see if I can fix that separately after this has gone in as a "good citizen" patch.

[vzakhari]

flang/lib/Optimizer/Transforms/SimplifyIntrinsics.cpp

58

Sure, the other places can be cleaned up separately.

[Leporacanthicus]

Added const to KindMapping argument.

[Leporacanthicus]

flang/lib/Optimizer/Transforms/SimplifyIntrinsics.cpp

81

I'm sure I fixed this before now. Anyway, thanks for spotting!

[vzakhari]

Thanks for the changes! LGTM