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Jakub Jelinek
authored
Given the https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113837#c9 comment, the following patch just attempts to implement what I think is best for ia32. Compared to https://gitlab.com/x86-psABIs/i386-ABI/-/issues/5 , like that patch for _BitInt(64) or smaller it uses the smallest containing {,un}signed {char,short,int,long long} for passing/returning and layout of variables including in structures for alignment/size, with any extra bits unspecified. Unlike the above proposal, for larger _BitInt (i.e. _BitInt(65)+), it uses passing/returning/layout/alignment of structure containing minimum needed number of 32-bit limbs, again with the extra bits unspecified. This is because most operations (except copy or bitwise ops) on _BitInts aren't really vectorizable and will be under the hood implemented in loops over 32-bit limbs anyway (using 64-bit limbs under the hood would mean often using library implementation for the basic operations) and because ia32 doesn't align even long long/double in structures to 64-bit I think it is better to just use 32-bit alignment for that. And I don't see a reason to waste 32-bit bits say for _BitInt(224) or _BitInt(288) on ia32. So, effectively it is like the x86-64 _BitInt ABI with everything divided by 2, the only exception is that in x86-64 psABI _BitInt(128) is said to be already a structure of 2 limbs, which happens to be passed mostly the same as __int128 (except for alignment). 2024-02-26 Jakub Jelinek <jakub@redhat.com> * config/i386/i386.cc (ix86_bitint_type_info): Add support for !TARGET_64BIT.