Some operations like the gpu.func have arguments that need to stay in place while rewriting the signature. This is the case for the workgroup and private attribution. Update the target rewrite pass to be aware of that when adding argument at the end of the function signature. If any trailing arguments are present, the new argument will be inserted just before them.
TargetRewrite is doing a shallow rewrite of function signatures. It is only rewriting function definitions (FuncOp), calls (CallOp) and AddressOfOp. It is not trying to visit each operations that may have an operand with a function type. It therefore needs function signature casts around the operations it is rewriting. Currently, these casts were not inserted after AddressOfOp rewrites because lowering tends to always insert function cast after generating AddressOfOp to the void type so the pass relied on implicitly updating this cast operand type to get the required cast. This is brittle because there is no guarantee such convert must be here and canonicalization and passes may remove them. Insert a cast after on the result of rewritten operations. If it is redundant, it will be canonicalized away later.
TargetRewritePass was dropping fast-math flags. Add the flags to the new call ops and update tests.
So far, flang was not setting argument attributes on direct calls assuming that putting them on the function operation was enough. It was clarified in https://github.com/llvm/llvm-project/commit/38565da5259729898c2a552d54b72f3314241734 that they must be set on both call and functions, even for direct calls. Crashes have been observed because of the lack of the attribute when compiling `abs(x)` at `O2` and above on X86-64 for complex(16).
Last piece that implements the TODO for sret and byval setting on indirect calls. This includes a fix to the codegen last patch. I thought types in in type attributes were automatically converted in dialect conversion passes, but that is not the case. The sret and byval type needs to be converted to llvm types in codegen (mlir FuncOp conversion is doing a similar conversion).
This patch shares core interface methods dealing with argument and result attributes from CallableOpInterface with the CallOpInterface and makes them mandatory to gives more consistent guarantees about concrete operations using these interfaces. This allows adding argument attributes on call like operations, which is sometimes required to get proper ABI, like with llvm.call (and llvm.invoke). The patch adds optional `arg_attrs` and `res_attrs` attributes to operations using these interfaces that did not have that already. They can then re-use the common "rich function signature" printing/parsing helpers if they want (for the LLVM dialect, this is done in the next patch). Part of RFC: https://discourse.llvm.org/t/mlir-rfc-adding-argument-and-result-attributes-to-llvm-call/84107