commit fae0d5c3005f711bff438603550b25df939a3da5
author cmtice <cmtice@google.com> Wed Jul 22 18:27:46 2015
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> Wed Jul 22 22:29:54 2015
tree 0ed6e7104478b4d10d8e7f15268fececc532dd39
parent d86e6bd86fde8cd6a6cb325740cd21c37d6a5d54

Backport patch from GCC FSF to fix stack problem for aarch64:

2014-11-04  Jiong Wang  <jiong.wang@arm.com>
2014-11-04  Wilco Dijkstra  <wilco.dijkstra@arm.com>

  PR target/63293
  * config/aarch64/aarch64.c (aarch64_expand_epiloue): Add barriers
  before stack adjustment.

BUG=chromium:509102
TEST=Built test cases before and after change, with various flags, and
examined assembly code to see if the problem was there and verified
the patch fixed the problem when present.

Change-Id: Ief52b321bca87ddf98445db8f8d402554ba3aee3
Reviewed-on: https://chromium-review.googlesource.com/287448
Reviewed-by: Luis Lozano <llozano@chromium.org>
Commit-Queue: Caroline Tice <cmtice@chromium.org>
Tested-by: Caroline Tice <cmtice@chromium.org>

gcc/config/aarch64/aarch64.c

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 029c54c..d491b59 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -2204,6 +2204,9 @@
   HOST_WIDE_INT fp_offset;
   rtx insn;
   rtx cfa_reg;
+  /* We need to add memory barrier to prevent read from deallocated stack.  */
+  bool need_barrier_p = (get_frame_size() != 0
+			 || cfun->machine->saved_varargs_size);
 
   aarch64_layout_frame ();
   original_frame_size = get_frame_size () + cfun->machine->saved_varargs_size;
@@ -2245,6 +2248,9 @@
   if (frame_pointer_needed
       && (crtl->outgoing_args_size || cfun->calls_alloca))
     {
+      if (cfun->calls_alloca)
+	emit_insn (gen_stack_tie (stack_pointer_rtx, stack_pointer_rtx));
+
       insn = emit_insn (gen_add3_insn (stack_pointer_rtx,
 				       hard_frame_pointer_rtx,
 				       GEN_INT (- fp_offset)));
@@ -2258,9 +2264,13 @@
   aarch64_save_or_restore_callee_save_registers
     (fp_offset + cfun->machine->frame.hardfp_offset, 1);
 
+  if (need_barrier_p)
+    emit_insn (gen_stack_tie (stack_pointer_rtx, stack_pointer_rtx));
+
   /* Restore the frame pointer and lr if the frame pointer is needed.  */
   if (offset > 0)
     {
+
       if (frame_pointer_needed)
 	{
 	  rtx mem_fp, mem_lr;
@@ -2355,6 +2365,9 @@
 
   if (frame_size > -1)
     {
+      if (need_barrier_p)
+	emit_insn (gen_stack_tie (stack_pointer_rtx, stack_pointer_rtx));
+
       if (frame_size >= 0x1000000)
 	{
 	  rtx op0 = gen_rtx_REG (Pmode, IP0_REGNUM);