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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-7458] calls: When bypassing emit_push_insn for 0 sized arg, emit at least anti_adjust_stack for alignment Date: Thu, 3 Mar 2022 08:12:30 +0000 (GMT) [thread overview] Message-ID: <20220303081230.DACF23858D39@sourceware.org> (raw) https://gcc.gnu.org/g:e6e6e0a97340068c90fe091482efbaacd6474754 commit r12-7458-ge6e6e0a97340068c90fe091482efbaacd6474754 Author: Jakub Jelinek <jakub@redhat.com> Date: Thu Mar 3 09:11:09 2022 +0100 calls: When bypassing emit_push_insn for 0 sized arg, emit at least anti_adjust_stack for alignment pad if needed [PR104558] The following testcase ICEs on x86_64 when asked to use the pre-GCC 8 ABI where zero sized arguments weren't ignored. In GCC 7 the emit_push_insn calls in store_one_arg were unconditional, it is true that they didn't actually push anything because it had zero size, but because arg->locate.alignment_pad is 8 in this case, emit_push_insn at the end performs if (alignment_pad && args_addr == 0) anti_adjust_stack (alignment_pad); and an assert larger on is upset if we don't do it. The following patch keeps the emit_push_insn conditional but calls the anti_adjust_stack when needed by hand for the zero sized arguments. For the new x86_64 ABI where zero sized arguments are ignored arg->locate.alignment_pad is 0 in this case, so nothing changes - we in that case really do ignore it. There is another emit_push_insn call earlier in store_one_arg, also made conditional on non-zero size by Marek in GCC 8, but that one is for arguments with non-BLKmode and the only way those can be zero size is if they are TYPE_EMPTY_P aka when they are completely ignored. But I believe arg->locate.alignment_pad should be 0 in that case, so IMHO there is no need to do anything in the second spot. 2022-03-03 Jakub Jelinek <jakub@redhat.com> PR middle-end/104558 * calls.cc (store_one_arg): When not calling emit_push_insn because size_rtx is const0_rtx, call at least anti_adjust_stack on arg->locate.alignment_pad if !argblock and the alignment might be non-zero. * gcc.dg/pr104558.c: New test. Diff: --- gcc/calls.cc | 7 +++++++ gcc/testsuite/gcc.dg/pr104558.c | 15 +++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/gcc/calls.cc b/gcc/calls.cc index e64a937ea33..58864d0fdb3 100644 --- a/gcc/calls.cc +++ b/gcc/calls.cc @@ -5139,6 +5139,13 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags, ARGS_SIZE_RTX (arg->locate.offset), reg_parm_stack_space, ARGS_SIZE_RTX (arg->locate.alignment_pad), false); + /* If we bypass emit_push_insn because it is a zero sized argument, + we still might need to adjust stack if such argument requires + extra alignment. See PR104558. */ + else if ((arg->locate.alignment_pad.var + || maybe_ne (arg->locate.alignment_pad.constant, 0)) + && !argblock) + anti_adjust_stack (ARGS_SIZE_RTX (arg->locate.alignment_pad)); /* Unless this is a partially-in-register argument, the argument is now in the stack. diff --git a/gcc/testsuite/gcc.dg/pr104558.c b/gcc/testsuite/gcc.dg/pr104558.c new file mode 100644 index 00000000000..382fe5732d7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr104558.c @@ -0,0 +1,15 @@ +/* PR middle-end/104558 */ +/* { dg-do compile } */ +/* { dg-options "-fabi-version=9" } */ + +struct __attribute__ ((aligned)) A {}; + +struct A a; + +void bar (int, int, int, int, int, int, int, struct A); + +void +foo (void) +{ + bar (0, 1, 2, 3, 4, 5, 6, a); +}
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