[PATCH 4/4] ASAN for MIPS: Add gcc port bits for MIPS to support -fsanitize=address.

[Hans-Peter Nilsson]

Attribution to Jean Lee for spotting the right shadow-offset for
MIPS and for cheering on. :)  See xtensa and rs6000 back-ends for
the FRAME_GROWS_DOWNWARD construct.

gcc:

2018-03-22  Hans-Peter Nilsson  <h...@axis.com>
            Jean Lee  <xiaoyur...@gmail.com>

        * config/mips/mips.c (mips_asan_shadow_offset): New function.
        (TARGET_ASAN_SHADOW_OFFSET): Define.
        * config/mips/mips.h (FRAME_GROWS_DOWNWARD): Augment to also be
        true for -fsanitize=address.

diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index aabd4b1..bfe64bb 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -22307,6 +22307,14 @@ mips_constant_alignment (const_tree exp, HOST_WIDE_INT 
align)
   return align;
 }
 
+/* Implement the TARGET_ASAN_SHADOW_OFFSET hook.  */
+
+static unsigned HOST_WIDE_INT
+mips_asan_shadow_offset (void)
+{
+  return 0x0aaa0000;
+}
+
 /* Implement TARGET_STARTING_FRAME_OFFSET.  See mips_compute_frame_info
    for details about the frame layout.  */
 
@@ -22618,6 +22626,9 @@ mips_starting_frame_offset (void)
 #undef TARGET_CONSTANT_ALIGNMENT
 #define TARGET_CONSTANT_ALIGNMENT mips_constant_alignment
 
+#undef TARGET_ASAN_SHADOW_OFFSET
+#define TARGET_ASAN_SHADOW_OFFSET mips_asan_shadow_offset
+
 #undef TARGET_STARTING_FRAME_OFFSET
 #define TARGET_STARTING_FRAME_OFFSET mips_starting_frame_offset
 
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 84ae675..f290560 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -2289,7 +2289,8 @@ enum reg_class
 
 #define STACK_GROWS_DOWNWARD 1
 
-#define FRAME_GROWS_DOWNWARD flag_stack_protect
+#define FRAME_GROWS_DOWNWARD (flag_stack_protect != 0                  \
+                             || (flag_sanitize & SANITIZE_ADDRESS) != 0)
 
 /* Size of the area allocated in the frame to save the GP.  */
 
-- 
2.1.4

brgds, H-P