From 03d5e89e7f3be53fd7142556e8e0a2774c653dca Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 12 Sep 2023 16:08:49 +0100 Subject: [PATCH 12/28] 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.cc (aarch64_layout_frame): Explicitly allocate the frame in one go if there are no saved registers. --- gcc/config/aarch64/aarch64.cc | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc index 79253322fd7c..e1f21230c15e 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -8378,9 +8378,11 @@ 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: -- 2.42.0