[MLIR][LLVM] Copy byval attributes during inlining.

[definelicht]

Summary

Support inlining of function calls with the byval attribute on function
arguments by copying the pointee into a newly alloca'ed pointer at the
callsite before inlining.

The alignment attribute is not yet taken into account.

[ftynse]

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

2995–2997

Please expand auto unless the type is obvious from context (e.g., there's a cast on the RHS) or impossible to spell (e.g., lambdas).

3002

Nit: consider early return here.

[gysit]

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

3001

Should this also be a check for write-only accesses?

memoryEffects &&
memoryEffects.getArgMem() != ModRefInfo::ModRef &&
memoryEffects.getArgMem() != ModRefInfo::Mod

Or does ModRef also match pure write accesses?

[definelicht]

Addressed comments by moving byval handling into a separate function so we can do early returns without breaking the control flow of other potential function argument attribute handling.

[definelicht]

Add missing check for write-only.

[gysit]

Thanks LGTM!

[definelicht]

Get data layout from callable, omit call argument, and remove auto.