[Patch AArch64 2/2] Do not double-copy bytes in volatile struct operations

[James Greenhalgh]

Hi,

We also need to be careful in AArch64's movmem implementation, we
can't expand to our overlapping mode of operation.

Bootstrapped with no issues.

OK?

Thanks,
James

---

2014-08-21  James Greenhalgh  <james.greenha...@arm.com>

        * config/aarch64/aarch64.c (aarch64_expand_movmem): Fail if we
        have volatile operands.

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 0f3c74b..56434bc 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -9741,6 +9741,10 @@ aarch64_expand_movmem (rtx *operands)
   if (!CONST_INT_P (operands[2]))
     return false;
 
+  /* We can't do anything smart if either of the operands are volatile.  */
+  if (MEM_VOLATILE_P (src) || MEM_VOLATILE_P (dst))
+    return false;
+
   n = UINTVAL (operands[2]);
 
   /* Try to keep the number of instructions low.  For cases below 16 bytes we