(store_split_bit_field): If OP0 is a SUBREG, then compute WORD from the base register...

(store_split_bit_field): If OP0 is a SUBREG, then
compute WORD from the base register, instead of from the SUBREG.
(extract_split_bit_field): Likewise.
(extract_bit_field): Sign-extend multiword bitfield if necessary.

From-SVN: r6668

diff --git a/gcc/expmed.c b/gcc/expmed.c
index 5a06dbf5dc2def29e15e7b3e7489b4e5aff494f6..1d5d75eddac7b45fbcea06f7293fc5b586f64fee 100644 (file)
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -757,8 +757,19 @@ store_split_bit_field (op0, bitsize, bitpos, value, align)
 #endif
 
       /* If OP0 is a register, then handle OFFSET here.
-        In the register case, UNIT must be a whole word.  */
-      if (GET_CODE (op0) == SUBREG || GET_CODE (op0) == REG)
+
+        When handling multiword bitfields, extract_bit_field may pass
+        down a word_mode SUBREG of a larger REG for a bitfield that actually
+        crosses a word boundary.  Thus, for a SUBREG, we must find
+        the current word starting from the base register.  */
+      if (GET_CODE (op0) == SUBREG)
+       {
+         word = operand_subword (SUBREG_REG (op0),
+                                 SUBREG_WORD (op0) + offset, 1,
+                                 GET_MODE (SUBREG_REG (op0)));
+         offset = 0;
+       }
+      else if (GET_CODE (op0) == REG)
        {
          word = operand_subword (op0, offset, 1, GET_MODE (op0));
          offset = 0;
@@ -917,7 +928,15 @@ extract_bit_field (str_rtx, bitsize, bitnum, unsignedp,
            emit_move_insn (target_part, result_part);
        }
 
-      return target;
+      if (unsignedp)
+       return target;
+      /* Signed bit field: sign-extend with two arithmetic shifts.  */
+      target = expand_shift (LSHIFT_EXPR, mode, target,
+                            build_int_2 (GET_MODE_BITSIZE (mode) - bitsize, 0),
+                            NULL_RTX, 0);
+      return expand_shift (RSHIFT_EXPR, mode, target,
+                          build_int_2 (GET_MODE_BITSIZE (mode) - bitsize, 0),
+                          NULL_RTX, 0);
     }
   
   /* From here on we know the desired field is smaller than a word
@@ -1505,8 +1524,19 @@ extract_split_bit_field (op0, bitsize, bitpos, unsignedp, align)
       thissize = MIN (thissize, unit - thispos);
 
       /* If OP0 is a register, then handle OFFSET here.
-        In the register case, UNIT must be a whole word.  */
-      if (GET_CODE (op0) == SUBREG || GET_CODE (op0) == REG)
+
+        When handling multiword bitfields, extract_bit_field may pass
+        down a word_mode SUBREG of a larger REG for a bitfield that actually
+        crosses a word boundary.  Thus, for a SUBREG, we must find
+        the current word starting from the base register.  */
+      if (GET_CODE (op0) == SUBREG)
+       {
+         word = operand_subword_force (SUBREG_REG (op0),
+                                       SUBREG_WORD (op0) + offset,
+                                       GET_MODE (SUBREG_REG (op0)));
+         offset = 0;
+       }
+      else if (GET_CODE (op0) == REG)
        {
          word = operand_subword_force (op0, offset, GET_MODE (op0));
          offset = 0;