Re: [PATCH AArch64]: Add constraint letter for stack_protect_test pattern)

[James Greenhalgh]

On Wed, Sep 17, 2014 at 09:30:31AM +0100, Richard Earnshaw wrote:
> "=&r" is correct for an early-clobbered scratch.
>
> R.

In that case...

How is the attached patch for trunk? I've bootstrapped it on AArch64
with -fstack-protector-strong and -frename-registers in the BOOT_CFLAGS
without seeing any issues.

OK?

Thanks,
James

---
gcc/

2014-09-15  James Greenhalgh  <james.greenha...@arm.com>

        * config/aarch64/aarch64.md (stack_protect_test_<mode>): Mark
        scratch register as an output to placate register renaming.

gcc/testsuite/

2014-09-15  James Greenhalgh  <james.greenha...@arm.com>

        * gcc.target/aarch64/stack_protector_set_1.c: New.
        * gcc.target/aarch64/stack_protector_set_2.c: Likewise.

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index c60038a9015d614f40f6d9e3fd228ad3e2b247a8..f15a516bb0559c86bea7512f91d60dc179ec9149 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -4031,7 +4031,7 @@ (define_insn "stack_protect_test_<mode>"
 	(unspec:PTR [(match_operand:PTR 1 "memory_operand" "m")
 		     (match_operand:PTR 2 "memory_operand" "m")]
 	 UNSPEC_SP_TEST))
-   (clobber (match_scratch:PTR 3 "&r"))]
+   (clobber (match_scratch:PTR 3 "=&r"))]
   ""
   "ldr\t%<w>3, %x1\;ldr\t%<w>0, %x2\;eor\t%<w>0, %<w>3, %<w>0"
   [(set_attr "length" "12")
diff --git a/gcc/testsuite/gcc.target/aarch64/stack_protector_set_1.c b/gcc/testsuite/gcc.target/aarch64/stack_protector_set_1.c
new file mode 100644
index 0000000..df0d26b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/stack_protector_set_1.c
@@ -0,0 +1,15 @@
+/* { dg-do assemble } */
+/* { dg-options "-fstack-protector-strong -O1 -frename-registers" } */
+
+extern int bar (const char *s, int *argc);
+extern int baz (const char *s);
+
+char
+foo (const char *s)
+{
+  int argc;
+  int ret;
+  if ( !bar (s, &argc))
+    ret = baz (s);
+  return *s;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/stack_protector_set_2.c b/gcc/testsuite/gcc.target/aarch64/stack_protector_set_2.c
new file mode 100644
index 0000000..b94a2d6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/stack_protector_set_2.c
@@ -0,0 +1,17 @@
+/* { dg-do assemble } */
+/* { dg-options "-fstack-protector-strong -O1 -frename-registers" } */
+
+typedef unsigned int uint32_t;
+struct ctx
+{
+  uint32_t A;
+};
+
+void *
+buffer_copy (const struct ctx *ctx, void *resbuf)
+{
+  uint32_t buffer[4];
+  buffer[0] = (ctx->A);
+  __builtin_memcpy (resbuf, buffer, 16);
+  return resbuf;
+}