https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116413
--- Comment #19 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:708ee71808ea61758e73d0e36274b4194b28576a commit r15-3213-g708ee71808ea61758e73d0e36274b4194b28576a Author: Richard Sandiford <richard.sandif...@arm.com> Date: Tue Aug 27 09:48:28 2024 +0100 Handle arithmetic on eliminated address indices [PR116413] This patch fixes gcc.c-torture/compile/opout.c for m68k with LRA enabled. The test has: ... z (a, b) { return (int) &a + (int) &b + (int) x + (int) z; } so it adds the address of two incoming arguments. This ends up being treated as an LEA in which the "index" is the incoming argument pointer, which the LEA multiplies by 2. The incoming argument pointer is then eliminated, leading to: (plus:SI (plus:SI (ashift:SI (plus:SI (reg/f:SI 24 %argptr) (const_int -4 [0xfffffffffffffffc])) (const_int 1 [0x1])) (reg/f:SI 41 [ _6 ])) (const_int 20 [0x14])) In the address_info scheme, the innermost plus has to be treated as the index "term", since that's the thing that's subject to index_reg_class. gcc/ PR middle-end/116413 * rtl.h (address_info): Update commentary. * rtlanal.cc (valid_base_or_index_term_p): New function, split out from... (get_base_term, get_index_term): ...here. Handle elimination PLUSes.
