[PATCH 8/8][GCC][AArch64] stack-clash: Add LR assert to layout_frame.

[Tamar Christina]

Hi All,

Since stack clash depends on the LR being saved for non-leaf functions this
patch adds an assert such that if this changes we would notice this.

Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.

This patch has been pre-approved by AArch64 maintainer here
  https://gcc.gnu.org/ml/gcc-patches/2018-09/msg00555.html
and will be committed with the rest.

Thanks,
Tamar

gcc/ChangeLog:

2018-09-26  Tamar Christina  <tamar.christ...@arm.com>

        * config/aarch64/aarch64.c (aarch64_layout_frame): Add assert.

-- 

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 283f3372798c84ef74356128acf2a5be7b4ce1ad..d4b13d48d852a70848fc7c51fd867e776efb5e55 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -4050,6 +4050,11 @@ aarch64_layout_frame (void)
       offset = 2 * UNITS_PER_WORD;
     }
 
+  /* With stack-clash, LR must be saved in non-leaf functions.  */
+  gcc_assert (crtl->is_leaf
+	      || (cfun->machine->frame.reg_offset[R30_REGNUM]
+		  != SLOT_NOT_REQUIRED));
+
   /* Now assign stack slots for them.  */
   for (regno = R0_REGNUM; regno <= R30_REGNUM; regno++)
     if (cfun->machine->frame.reg_offset[regno] == SLOT_REQUIRED)