[PATCH] D17183: Make TargetInfo store an actual DataLayout instead of a string.

Mon Mar 29 12:59:09 PDT 2021

jyknight added a comment.

In general, I think it's extremely unfortunate that Clang and LLVM have different copies of the same information. It's a problem for way more than just this one situation. So, I really don't like choice 1 -- I think it's moving in the wrong direction.

The recent thread about compiler-rt libcalls vs size of "int" is another example of this sort of issue of duplicated info across the llvm/clang boundary being troublesome. Other times, the information in question is buried in the Target implementation in LLVM, and Clang doesn't depend upon targets being compiled in...usually, so it can't access it from there. E.g. the fact that Clang even has to come up with a DataLayout string on its own is an example of this problem.

So, I like option 2. I think a lot more of the information in TargetInfo ought to be shared with LLVM. I note that ARM already pushed a bunch of shared stuff into LLVM to reduce duplication, which is great. But, it had to put it into a rather odd place (`llvm/include/llvm/Support/{ARMTargetParser.h,ARMAttributeParser.h,...`), because of the layering and optionality concerns. That part is not so great -- putting all this target-specific info into "Support" doesn't feel like the best fit. There should be some sort of Target-specific location for this sort of stuff to live which Clang can depend on.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D17183/new/

https://reviews.llvm.org/D17183