https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104679
--- Comment #2 from CVS 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:526fbcfa636fb7e544c1ad69101dbccecbee8b28 commit r12-7386-g526fbcfa636fb7e544c1ad69101dbccecbee8b28 Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Feb 25 10:56:46 2022 +0100 internal-fn: Call do_pending_stack_adjust in expand_SPACESHIP [PR104679] The following testcase is miscompiled on ia32 at -O2, because when expand_SPACESHIP is called, we have pending stack adjustment from the foo call right before it. Now, ix86_expand_fp_spaceship uses emit_jump_insn several times but then emit_jump also several times. While emit_jump_insn doesn't do do_pending_stack_adjust (), emit_jump does, so we end up with: ... 8: call [`_Z3foodl'] argc:0x10 REG_CALL_DECL `_Z3foodl' 9: r88:DF=[`a'] 10: r89:HI=unspec[cmp(r88:DF,0.0)] 25 11: flags:CC=unspec[r89:HI] 26 12: pc={(unordered(flags:CCFP,0))?L27:pc} REG_BR_PROB 536868 66: NOTE_INSN_BASIC_BLOCK 4 13: pc={(uneq(flags:CCFP,0))?L19:pc} REG_BR_PROB 214748364 67: NOTE_INSN_BASIC_BLOCK 5 14: pc={(flags:CCFP>0)?L23:pc} REG_BR_PROB 536870916 68: NOTE_INSN_BASIC_BLOCK 6 15: r86:SI=0xffffffffffffffff 16: {sp:SI=sp:SI+0x10;clobber flags:CC;} REG_ARGS_SIZE 0 17: pc=L29 18: barrier 19: L19: 69: NOTE_INSN_BASIC_BLOCK 7 ... The sp += 16 pending stuck adjust was emitted in the middle of the sequence and is effective only for the single case of the 4 possibilities where .SPACESHIP returns -1, in all other cases the stack isn't adjusted and so we ICE during dwarf2cfi. Now, we could either call do_pending_stack_adjust in ix86_expand_fp_spaceship, or use there calls that actually don't call do_pending_stack_adjust (but having the stack adjustment across branches is generally undesirable), or we can call it in expand_SPACESHIP for all targets (note, just i386 currently implements it). I chose the generic code because e.g. expand_{addsub,neg,mul}_overflow in the same file also call do_pending_stack_adjust in internal-fn.cc for the same reasons, that it is expected that most if not all targets will expand those through jumps and we don't want all of the targets to need to deal with that. 2022-02-25 Jakub Jelinek <ja...@redhat.com> PR middle-end/104679 * internal-fn.cc (expand_SPACESHIP): Call do_pending_stack_adjust. * g++.dg/torture/pr104679.C: New test.
