[backport from gcc-4.7/trunk <mikpe@it.uu.se>]

gcc/

2011-03-17  Chung-Lin Tang  <cltang@codesourcery.com>

	PR target/43872
	* config/arm/arm.c (arm_get_frame_offsets): Adjust early
	return condition with !cfun->calls_alloca.

--- gcc-4.6-20110318/gcc/config/arm/arm.c.~1~	2011-01-29 04:20:57.000000000 +0100
+++ gcc-4.6-20110318/gcc/config/arm/arm.c	2011-03-21 10:58:46.000000000 +0100
@@ -15415,7 +15415,10 @@ arm_get_frame_offsets (void)
   offsets->soft_frame = offsets->saved_regs + CALLER_INTERWORKING_SLOT_SIZE;
   /* A leaf function does not need any stack alignment if it has nothing
      on the stack.  */
-  if (leaf && frame_size == 0)
+  if (leaf && frame_size == 0
+      /* However if it calls alloca(), we have a dynamically allocated
+	 block of BIGGEST_ALIGNMENT on stack, so still do stack alignment.  */
+      && ! cfun->calls_alloca)
     {
       offsets->outgoing_args = offsets->soft_frame;
       offsets->locals_base = offsets->soft_frame;