After simplifying the operands of a PLUS, canon_rtx checked only
for cases in which one of the simplified operands was a constant,
falling back to gen_rtx_PLUS otherwise. This left the PLUS in a
non-canonical order if one of the simplified operands was
(plus (reg R1) (const_int X)); we'd end up with:
(plus (plus (reg R1) (const_int Y)) (reg R2))
rather than:
(plus (plus (reg R1) (reg R2)) (const_int Y))
Fixing this exposed new DSE opportunities on spu-elf in
gcc.c-torture/execute/builtins/strcat-chk.c but otherwise
it doesn't seem to have much practical effect.
Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
Thanks,
Richard
[ This patch is part of the SVE series posted here:
https://gcc.gnu.org/ml/gcc/2016-11/msg00030.html ]
gcc/
2016-11-15 Richard Sandiford <richard.sandiford@arm.com>
Alan Hayward <alan.hayward@arm.com>
David Sherwood <david.sherwood@arm.com>
* alias.c (canon_rtx): Use simplify_gen_binary.