[PATCH] D78437: [AVR] Do not use divmod calls for bigger integers
Ayke via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sat Apr 18 15:05:41 PDT 2020
aykevl created this revision.
aykevl added a reviewer: dylanmckay.
Herald added subscribers: Jim, hiraditya.
Herald added a project: LLVM.
aykevl edited the summary of this revision.
The avr-libc provides `*divmodqi4`, `*divmodhi4`, and `*divmodsi4` functions, but does not provide a `*divmoddi4`. Instead it provides regular `*divdi3` and `*moddi3` functions.
Note that avr-libc doesn't support `*divti3` or `*modti3` for 128-bit integer manipulation, but because we have to do something with it it seemed most sensible to me to lower these as `*divt3`/`*modt3` too.
Source: https://github.com/gcc-mirror/gcc/blob/releases/gcc-5.4.0/libgcc/config/avr/lib1funcs.S
I suspect that avr-libc uses separate division and modulo functions for 64-bit integers because otherwise the return value would become really big (16 bytes) and would have to be passed on the stack.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D78437
Files:
llvm/lib/Target/AVR/AVRISelLowering.cpp
llvm/test/CodeGen/AVR/div.ll
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