Backport of 0f801e0b6cc9f67c9a8983127e23161f6025c5b6

Index: gcc/config/aarch64/aarch64.c
===================================================================
--- gcc/config/aarch64/aarch64.c	(revision 278213)
+++ gcc/config/aarch64/aarch64.c	(working copy)
@@ -13453,7 +13453,6 @@ aarch64_copy_one_block_and_progress_poin
 bool
 aarch64_expand_movmem (rtx *operands)
 {
-  unsigned int n;
   rtx dst = operands[0];
   rtx src = operands[1];
   rtx base;
@@ -13467,7 +13466,7 @@ aarch64_expand_movmem (rtx *operands)
   if (!CONST_INT_P (operands[2]))
     return false;
 
-  n = UINTVAL (operands[2]);
+  unsigned HOST_WIDE_INT n = UINTVAL (operands[2]);
 
   /* Try to keep the number of instructions low.  For cases below 16 bytes we
      need to make at most two moves.  For cases above 16 bytes it will be one