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From: Richard Sandiford <rsandifo@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/vendors/ARM/heads/CVE-2023-4039/gcc-10)] aarch64: Explicitly handle frames with no saved registers Date: Tue, 12 Sep 2023 15:24:40 +0000 (GMT) [thread overview] Message-ID: <20230912152440.55C0D385E020@sourceware.org> (raw) https://gcc.gnu.org/g:c8ffe35ca907e0042524a5369158fcb5631d5108 commit c8ffe35ca907e0042524a5369158fcb5631d5108 Author: Richard Sandiford <richard.sandiford@arm.com> Date: Fri Jun 16 17:00:51 2023 +0100 aarch64: Explicitly handle frames with no saved registers If a frame has no saved registers, it can be allocated in one go. There is no need to treat the areas below and above the saved registers as separate. And if we allocate the frame in one go, it should be allocated as the initial_adjust rather than the final_adjust. This allows the frame size to grow to guard_size - guard_used_by_caller before a stack probe is needed. (A frame with no register saves is necessarily a leaf frame.) This is a no-op as thing stand, since a leaf function will have no outgoing arguments, and so all the frame will be above where the saved registers normally go. gcc/ * config/aarch64/aarch64.c (aarch64_layout_frame): Explicitly allocate the frame in one go if there are no saved registers. Diff: --- gcc/config/aarch64/aarch64.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index 2aaf187bcc3f..81537c019511 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -7035,9 +7035,11 @@ aarch64_layout_frame (void) HOST_WIDE_INT const_size, const_outgoing_args_size, const_fp_offset; HOST_WIDE_INT const_saved_regs_size; - if (frame.frame_size.is_constant (&const_size) - && const_size < max_push_offset - && known_eq (frame.hard_fp_offset, const_size)) + if (known_eq (frame.saved_regs_size, 0)) + frame.initial_adjust = frame.frame_size; + else if (frame.frame_size.is_constant (&const_size) + && const_size < max_push_offset + && known_eq (frame.hard_fp_offset, const_size)) { /* Simple, small frame with no outgoing arguments:
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