https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120424
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Alexandre Oliva <aol...@gcc.gnu.org>: https://gcc.gnu.org/g:2edb50a310896da72710dba7724a3b4a541a1cbb commit r16-1065-g2edb50a310896da72710dba7724a3b4a541a1cbb Author: Alexandre Oliva <ol...@adacore.com> Date: Mon Jun 2 20:21:45 2025 -0300 [lra] force reg update after spilling to memory [PR120424] In the added C++ testcase, a stack slot at a negative sp offset is used to hold a value across a call. There are a couple of causes that directly lead to this outcome: - the -fstack-clash-protection and -fnon-call-exception options, that cause arm_frame_pointer_required to flip from false to true when the first pseudo gets spilled to memory; - when the affected pseudo is spilled to memory, we fail to update lra regno info, because the insns that reference it are already on the lra_constraint_insn_stack; There is another potentially-related issue: - when we notice that the frame pointer can no longer be eliminated to the stack pointer, we immediately clear can_eliminate, and also prev_can_eliminate, but update_reg_eliminate relied on the latter to tell that it needs to propagate a previous_offset to the newly-selected elimination, or restore the original offsets. This patch ensures that we update insn register info after spilling a pseudo to memory, and enables update_reg_eliminate to recognize the case in which a previously-preferred elimination is disabled regardless of prev_can_eliminate. for gcc/ChangeLog PR rtl-optimization/120424 PR middle-end/118939 * lra-spills.cc (spill_pseudos): Update insn regno info. * lra-eliminations.cc (update_reg_eliminate): Recognize disabling of active elimination regardless of prev_can_eliminate. for gcc/testsuite/ChangeLog PR rtl-optimization/120424 PR middle-end/118939 * g++.target/arm/pr120424.C: New. * gnat.dg/controlled9.adb: New. * gnat.dg/controlled9_pkg.ads: New.
