uweigand added inline comments.
================
Comment at: lib/Headers/__stddef_max_align_t.h:40
__attribute__((__aligned__(__alignof__(long double))));
+#ifdef __i386__
+ __float128 __clang_max_align_nonce3
----------------
jyknight wrote:
> Can you fix clang to consistently define `__SIZEOF_FLOAT128__` in
> InitPreprocessor alongside the rest of the SIZEOF macros?
>
> And then use that to determine whether to add float128 to the union? This
> change, as is, will break on any target which is i386 but doesn't define
> __float128, e.g. i386-unknown-unknown.
>
> The only additional target which will be modified with that (that is: the
> only other target which has a float128 type, but for which max_align isn't
> already 16) is systemz-*-linux.
>
> But I think that's actually indicating a pre-existing bug in the SystemZ
> config -- it's configured for a 16-byte long double, with 8-byte alignment,
> but the ABI doc seems to call for 16-byte alignment. +Ulrich for comment on
> that.
That's a bug in the ABI doc which we'll fix once we get around to releasing an
updated version.
long double on SystemZ must be 8-byte aligned, which is the maximum alignment
of all standard types on Z, and this was chosen because historically the ABI
only guarantees an 8-byte stack alignment, so 16-byte aligned standard types
would be awkward.
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D55057/new/
https://reviews.llvm.org/D55057
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