expr.c (store_field): Do a block copy from BLKmode to BLKmode-like.

	* expr.c (store_field): Do a block copy from BLKmode to BLKmode-like.
	(get_inner_reference): Use BLKmode for byte-aligned BLKmode bitfields.

From-SVN: r136699

gcc/ChangeLog

+2008-06-12  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* expr.c (store_field): Do a block copy from BLKmode to BLKmode-like.
+	(get_inner_reference): Use BLKmode for byte-aligned BLKmode bitfields.
+
 2008-06-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/36506

gcc/expr.c

@@ -5795,13 +5795,19 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
 	  && mode != TYPE_MODE (TREE_TYPE (exp)))
 	temp = convert_modes (mode, TYPE_MODE (TREE_TYPE (exp)), temp, 1);
 
-      /* If the modes of TARGET and TEMP are both BLKmode, both
+      /* If the modes of TEMP and TARGET are both BLKmode, both
 	 must be in memory and BITPOS must be aligned on a byte
-	 boundary.  If so, we simply do a block copy.  */
-      if (GET_MODE (target) == BLKmode && GET_MODE (temp) == BLKmode)
+	 boundary.  If so, we simply do a block copy.  Likewise
+	 for a BLKmode-like TARGET.  */
+      if (GET_MODE (temp) == BLKmode
+	  && (GET_MODE (target) == BLKmode
+	      || (MEM_P (target)
+		  && GET_MODE_CLASS (GET_MODE (target)) == MODE_INT
+		  && (bitpos % BITS_PER_UNIT) == 0
+		  && (bitsize % BITS_PER_UNIT) == 0)))
 	{
 	  gcc_assert (MEM_P (target) && MEM_P (temp)
-		      && !(bitpos % BITS_PER_UNIT));
+		      && (bitpos % BITS_PER_UNIT) == 0);
 
 	  target = adjust_address (target, VOIDmode, bitpos / BITS_PER_UNIT);
 	  emit_block_move (target, temp,
@@ -5847,12 +5853,11 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
    If any of the extraction expressions is volatile,
    we store 1 in *PVOLATILEP.  Otherwise we don't change that.
 
-   If the field is a bit-field, *PMODE is set to VOIDmode.  Otherwise, it
-   is a mode that can be used to access the field.  In that case, *PBITSIZE
-   is redundant.
+   If the field is a non-BLKmode bit-field, *PMODE is set to VOIDmode.
+   Otherwise, it is a mode that can be used to access the field.
 
    If the field describes a variable-sized object, *PMODE is set to
-   VOIDmode and *PBITSIZE is set to -1.  An access cannot be made in
+   BLKmode and *PBITSIZE is set to -1.  An access cannot be made in
    this case, but the address of the object can be found.
 
    If KEEP_ALIGNING is true and the target is STRICT_ALIGNMENT, we don't
@@ -5877,6 +5882,7 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
 {
   tree size_tree = 0;
   enum machine_mode mode = VOIDmode;
+  bool blkmode_bitfield = false;
   tree offset = size_zero_node;
   tree bit_offset = bitsize_zero_node;
 
@@ -5884,11 +5890,14 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
      outermost expression.  */
   if (TREE_CODE (exp) == COMPONENT_REF)
     {
-      size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
-      if (! DECL_BIT_FIELD (TREE_OPERAND (exp, 1)))
-	mode = DECL_MODE (TREE_OPERAND (exp, 1));
+      tree field = TREE_OPERAND (exp, 1);
+      size_tree = DECL_SIZE (field);
+      if (!DECL_BIT_FIELD (field))
+	mode = DECL_MODE (field);
+      else if (DECL_MODE (field) == BLKmode)
+	blkmode_bitfield = true;
 
-      *punsignedp = DECL_UNSIGNED (TREE_OPERAND (exp, 1));
+      *punsignedp = DECL_UNSIGNED (field);
     }
   else if (TREE_CODE (exp) == BIT_FIELD_REF)
     {
@@ -5922,8 +5931,6 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
 	*pbitsize = tree_low_cst (size_tree, 1);
     }
 
-  *pmode = mode;
-
   /* Compute cumulative bit-offset for nested component-refs and array-refs,
      and find the ultimate containing object.  */
   while (1)
@@ -6018,14 +6025,25 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
       if (double_int_fits_in_shwi_p (tem))
 	{
 	  *pbitpos = double_int_to_shwi (tem);
-	  *poffset = NULL_TREE;
-	  return exp;
+	  *poffset = offset = NULL_TREE;
 	}
     }
 
   /* Otherwise, split it up.  */
-  *pbitpos = tree_low_cst (bit_offset, 0);
-  *poffset = offset;
+  if (offset)
+    {
+      *pbitpos = tree_low_cst (bit_offset, 0);
+      *poffset = offset;
+    }
+
+  /* We can use BLKmode for a byte-aligned BLKmode bitfield.  */
+  if (mode == VOIDmode
+      && blkmode_bitfield
+      && (*pbitpos % BITS_PER_UNIT) == 0
+      && (*pbitsize % BITS_PER_UNIT) == 0)
+    *pmode = BLKmode;
+  else
+    *pmode = mode;
 
   return exp;
 }