[PATCH, middle-end]: FIX PR55253, [4.8 Regression] FAIL: gcc.target/i386/pr44948-2a.c

[Uros Bizjak]

Hello!

Attached patch fixes an oversight, introduced in Revision 192641 [1]
that caused following testsuite failure on i686:

FAIL: gcc.target/i386/pr44948-2a.c (internal compiler error)
FAIL: gcc.target/i386/pr44948-2a.c (test for excess errors)

As shown in the PR [2], the referred patch activated the call to
emit_block_move that was previously effectively dead code (see how
modes of temp and target are checked). emit_block_move ICEs when
constant is passed to it, so we got ICE for following arguments:

(gdb) p debug_rtx (x)
(mem/j/c:BLK (plus:SI (reg/f:SI 54 virtual-stack-vars)
        (const_int -16 [0xfffffffffffffff0])) [0 a.V4SF+0 S16 A128])
$1 = void
(gdb) p debug_rtx (y)
(const_vector:V4SF [
        (const_double:SF 0.0 [0x0.0p+0])
        (const_double:SF 1.0e+0 [0x0.8p+1])
        (const_double:SF 2.0e+0 [0x0.8p+2])
        (const_double:SF 3.0e+0 [0x0.cp+2])
    ])
$2 = void

The patch simply removes the call to emit_block_move, while still
calling copy_blkmode_from_reg when appropriate. The patch fixes the
testsuite failure and produces the same code as gcc-4.7.

2012-11-07  Uros Bizjak  <ubiz...@gmail.com>

        PR middle-end/55235
        * expr.c (store_expr): Do not call emit_block_move for
        non-BLKmode values.

Patch was bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32}.

OK for mainline?

[1] http://gcc.gnu.org/ml/gcc-cvs/2012-10/msg00764.html
[2] http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55235#c3

Uros.

Index: expr.c
===================================================================
--- expr.c      (revision 193296)
+++ expr.c      (working copy)
@@ -5246,19 +5246,12 @@ store_expr (tree exp, rtx target, int call_param_p
        {
          if (GET_MODE (target) == BLKmode)
            {
-             if (REG_P (temp))
-               {
-                 if (TREE_CODE (exp) == CALL_EXPR)
-                   copy_blkmode_from_reg (target, temp, TREE_TYPE (exp));
-                 else
-                   store_bit_field (target,
-                                    INTVAL (expr_size (exp)) * BITS_PER_UNIT,
-                                    0, 0, 0, GET_MODE (temp), temp);
-               }
+             if (REG_P (temp) && TREE_CODE (exp) == CALL_EXPR)
+               copy_blkmode_from_reg (target, temp, TREE_TYPE (exp));
              else
-               emit_block_move (target, temp, expr_size (exp),
-                                (call_param_p
-                                 ? BLOCK_OP_CALL_PARM : BLOCK_OP_NORMAL));
+               store_bit_field (target,
+                                INTVAL (expr_size (exp)) * BITS_PER_UNIT,
+                                0, 0, 0, GET_MODE (temp), temp);
            }
          else
            convert_move (target, temp, TYPE_UNSIGNED (TREE_TYPE (exp)));