[gcc(refs/vendors/ARM/heads/CVE-2023-4039/gcc-8)] aarch64: Explicitly handle frames with no saved registers

[Richard Sandiford]

https://gcc.gnu.org/g:f9e1c86b3397faa8dee4bbaeaf8b56492e3a63df

commit f9e1c86b3397faa8dee4bbaeaf8b56492e3a63df
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.
    
    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 4ad73220337f..ed9e2a28f914 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -4215,9 +4215,11 @@ aarch64_layout_frame (void)
     max_push_offset = 256;
 
   HOST_WIDE_INT const_size, const_fp_offset;
-  if (cfun->machine->frame.frame_size.is_constant (&const_size)
-      && const_size < max_push_offset
-      && known_eq (crtl->outgoing_args_size, 0))
+  if (cfun->machine->frame.saved_regs_size == 0)
+    cfun->machine->frame.initial_adjust = cfun->machine->frame.frame_size;
+  else if (cfun->machine->frame.frame_size.is_constant (&const_size)
+	   && const_size < max_push_offset
+	   && known_eq (crtl->outgoing_args_size, 0))
     {
       /* Simple, small frame with no outgoing arguments:
 	 stp reg1, reg2, [sp, -frame_size]!