https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112940
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:07efd5668537892e1c07264455bfd96f1a99a130 commit r14-6487-g07efd5668537892e1c07264455bfd96f1a99a130 Author: Jakub Jelinek <ja...@redhat.com> Date: Wed Dec 13 11:36:27 2023 +0100 lower-bitint: Fix lowering of non-_BitInt to _BitInt cast merged with some wider cast [PR112940] The following testcase ICEs, because a PHI argument from latch edge uses a SSA_NAME set only in a conditionally executed block inside of the loop. This happens when we have some outer cast which lowers its operand several times, under some condition with variable index, under different condition with some constant index, otherwise something else, and then there is an inner cast from non-_BitInt integer (or small/middle one). Such cast in certain conditions is emitted by initializing some SSA_NAMEs in the initialization statements before loops (say for casts from <= limb size precision by computing a SSA_NAME for the first limb and then extension of it for the later limbs) and uses the prepare_data_in_out function to create a PHI node. Such function is passed the value (constant or SSA_NAME) to use in the PHI argument from the pre-header edge, but for the latch edge it always created a new SSA_NAME and then caller emitted in the following 3 spots an extra assignment to set that SSA_NAME to whatever value we want from the latch edge. In all these 3 cases the argument from the latch edge is known already before the loop though, either constant or SSA_NAME computed in pre-header as well. But the need to emit an assignment combined with the handle_operand done in a conditional basic block results in the SSA verification failure. The following patch fixes it by extending the prpare_data_in_out method, so that when the latch edge argument is known before (constant or computed in pre-header), we can just use it directly and avoid the extra assignment that would normally be hopefully optimized away later to what we now emit directly. 2023-12-13 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/112940 * gimple-lower-bitint.cc (struct bitint_large_huge): Add another argument to prepare_data_in_out method defaulted to NULL_TREE. (bitint_large_huge::handle_operand): Pass another argument to prepare_data_in_out instead of emitting an assignment to set it. (bitint_large_huge::prepare_data_in_out): Add VAL_OUT argument. If non-NULL, use it as PHI argument instead of creating a new SSA_NAME. (bitint_large_huge::handle_cast): Pass rext as another argument to 2 prepare_data_in_out calls instead of emitting assignments to set them. * gcc.dg/bitint-53.c: New test.
