middle-end/117433 - ICE with gimple BLKmode reg copy

When we end up expanding a SSA name copy with BLKmode regs which can
happen for vectors, possibly wrapped in a NOP-conversion or
a PAREN_EXPR and we are not optimizing we can end up with two
BLKmode MEMs that expand_gimple_stmt_1 doesn't properly handle
when expanding, trying to emit_move_insn them.  Looking at store_expr
which what expand_gimple_stmt_1 is really doing reveals a lot of
magic that's missing.  It eventually falls back to emit_block_move
(store_expr isn't exported), so this is what I ended up using here
given I think we'll only have BLKmode "registers" for vectors.

	PR middle-end/117433
	* cfgexpand.cc (expand_gimple_stmt_1): Use emit_block_move
	when moving temp to BLKmode target.

	* gcc.dg/pr117433.c: New testcase.

Author: rguenth

gcc/cfgexpand.cc

@@ -4068,8 +4068,13 @@ expand_gimple_stmt_1 (gimple *stmt)
 	    else
 	      {
 		temp = force_operand (temp, target);
-		if (temp != target)
+		if (temp == target)
+		  ;
+		else if (GET_MODE (target) != BLKmode)
 		  emit_move_insn (target, temp);
+		else
+		  emit_block_move (target, temp, expr_size (lhs),
+				   BLOCK_OP_NORMAL);
 	      }
 	  }
       }

gcc/testsuite/gcc.dg/pr117433.c

@@ -0,0 +1,21 @@
+/* { dg-do run } */
+
+__attribute__((__vector_size__ (sizeof (long unsigned) * 8))) long unsigned b;
+
+void __attribute__((noipa))
+foo ()
+{
+  b += __builtin_assoc_barrier (b);
+}
+
+int main()
+{
+  int i;
+  for (i = 0; i < 8; ++i)
+    b[i] = i;
+  foo ();
+  for (i = 0; i < 8; ++i)
+    if (b[i] != 2*i)
+      __builtin_abort ();
+  return 0;
+}