https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113673
--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Roger Sayle <sa...@gcc.gnu.org>: https://gcc.gnu.org/g:d8b05aef77443e1d3d8f3f5d2c56ac49a503fee3 commit r15-1584-gd8b05aef77443e1d3d8f3f5d2c56ac49a503fee3 Author: Roger Sayle <ro...@nextmovesoftware.com> Date: Mon Jun 24 15:34:03 2024 +0100 PR tree-optimization/113673: Avoid load merging when potentially trapping. This patch fixes PR tree-optimization/113673, a P2 ice-on-valid regression caused by load merging of (ptr[0]<<8)+ptr[1] when -ftrapv has been specified. When the operator is | or ^ this is safe, but for addition of signed integer types, a trap may be generated/required, so merging this idiom into a single non-trapping instruction is inappropriate, confusing the compiler by transforming a basic block with an exception edge into one without. This revision implements Richard Biener's feedback to add an early check for stmt_can_throw_internal (cfun, stmt) to prevent transforming in the presence of any statement that could trap, not just overflow on addition. The one other tweak included in this patch is to mark the local function find_bswap_or_nop_load as static ensuring that it isn't called from outside this file, and guaranteeing that it is dominated by stmt_can_throw_internal checking. 2024-06-24 Roger Sayle <ro...@nextmovesoftware.com> Richard Biener <rguent...@suse.de> gcc/ChangeLog PR tree-optimization/113673 * gimple-ssa-store-merging.cc (find_bswap_or_nop_load): Make static. (find_bswap_or_nop_1): Avoid transformations (load merging) when stmt_can_throw_internal indicates that a statement can trap. gcc/testsuite/ChangeLog PR tree-optimization/113673 * g++.dg/pr113673.C: New test case.
