https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116516
--- Comment #6 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:ac6d433b02ce26a646b2a7254b1d87fcc06b0beb commit r15-3288-gac6d433b02ce26a646b2a7254b1d87fcc06b0beb Author: Richard Sandiford <richard.sandif...@arm.com> Date: Thu Aug 29 14:00:23 2024 +0100 Allow subregs around constant displacements [PR116516] This patch fixes a regression introduced by g:708ee71808ea61758e73. x86_64 allows addresses of the form: (zero_extend:DI (subreg:SI (symbol_ref:DI "foo") 0)) Before the previous patch, a lax SUBREG check meant that we would treat the subreg as a base and reload it into a base register. But that wasn't what the target was expecting. Instead we should treat "foo" as a constant displacement, to match: leal foo, <dest> After the patch, we recognised that "foo" isn't a base register, but ICEd on it rather than handling it as a displacement. With or without the recent patches, if the address had instead been: (zero_extend:DI (subreg:SI (plus:DI (reg:DI R) (symbol_ref:DI "foo") 0))) then we would have treated "foo" as the displacement and R as the base or index, as expected. The problem was that the code that does this was rejecting all subregs of objects, rather than just subregs of variable objects. gcc/ PR middle-end/116516 * rtlanal.cc (strip_address_mutations): Allow subregs around constant displacements. gcc/testsuite/ PR middle-end/116516 * gcc.c-torture/compile/pr116516.c: New test.
