[PATCH, ARM] Fix stack red zone bug (PR38644)

[Jiangning Liu]

Hi,

This patch is to fix PR38644 in ARM back-end. OK for trunk?

For every detail, please refer to
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38644.

ChangeLog:

2011-11-2  Jiangning Liu  <jiangning....@arm.com>

        PR rtl-optimization/38644
        * config/arm/arm.c (thumb1_expand_epilogue): Add memory barrier
        for epilogue having stack adjustment.

ChangeLog of testsuite:

2011-11-2  Jiangning Liu  <jiangning....@arm.com>

        PR rtl-optimization/38644
        * gcc.target/arm/stack-red-zone.c: New.

Thanks,
-Jiangning

Patch:

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index f1ada6f..1f6fc26
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -22215,6 +22215,8 @@ thumb1_expand_epilogue (void)
   gcc_assert (amount >= 0);
   if (amount)
     {
+      emit_insn (gen_blockage ());
+
       if (amount < 512)
        emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx,
                               GEN_INT (amount)));
diff --git a/gcc/testsuite/gcc.target/arm/stack-red-zone.c
b/gcc/testsuite/gcc.target/arm/stack-red-zone.c
new file mode 100644
index 0000000..b9f0f99
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/stack-red-zone.c
@@ -0,0 +1,12 @@
+/* No stack red zone.  PR38644.  */
+/* { dg-options "-mthumb -O2" } */
+/* { dg-final { scan-assembler "ldrb\[^\n\]*\\n\[\t \]*add\[\t \]*sp" } }
*/
+
+extern int doStreamReadBlock (int *, char *, int size, int);
+
+char readStream (int *s)
+{
+       char c = 0;
+       doStreamReadBlock (s, &c, 1, *s);
+       return c;
+}