[PATCH] D115441: [X86][MS] Add 80bit long double support for Windows

Fri Dec 10 19:57:38 PST 2021

rnk added a subscriber: mstorsjo.
rnk added a comment.

I seem to recall assuming that Windows `long double` was 64-bits in many, many places. Unfortunately, I have no idea where that could've happened. Something that comes to mind immediately is the MSVC name mangler. I don't think that's a blocking issue, but it's something you should be aware of if you want to promote this flag's usage.

@mstorsjo, can you advise what GCC does here? I've forgotten how this is supposed to work.

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Comment at: clang/lib/Basic/Targets/X86.h:537
     resetDataLayout(IsWinCOFF ? "e-m:x-p:32:32-p270:32:32-p271:32:32-p272:64:"
                                 "64-i64:64-f80:32-n8:16:32-a:0:32-S32"
                               : "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:"
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If GCC aligns f80 to 16 bytes, we might as well make the change here and share it with the mingw target.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115441/new/

https://reviews.llvm.org/D115441