Refine previous change.

[pf3gnuchains/gcc-fork.git] / gcc / stor-layout.c

diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c
index 0601440..e488741 100644 (file)
--- a/gcc/stor-layout.c
+++ b/gcc/stor-layout.c
@@ -2203,6 +2203,8 @@ initialize_sizetypes (void)
     precision = LONG_TYPE_SIZE;
   else if (strcmp (SIZE_TYPE, "long long unsigned int") == 0)
     precision = LONG_LONG_TYPE_SIZE;
+  else if (strcmp (SIZE_TYPE, "short unsigned int") == 0)
+    precision = SHORT_TYPE_SIZE;
   else
     gcc_unreachable ();
 
@@ -2245,7 +2247,11 @@ initialize_sizetypes (void)
     = size_int (GET_MODE_SIZE (TYPE_MODE (bitsizetype)));
   set_min_and_max_values_for_integral_type (bitsizetype, bprecision,
                                            /*is_unsigned=*/true);
-  /* ???  TYPE_MAX_VALUE is not properly sign-extended.  */
+  /* bitsizetype is unsigned but we need to fix TYPE_MAX_VALUE so that it is
+     sign-extended in a way consistent with force_fit_type.  */
+  TYPE_MAX_VALUE (bitsizetype)
+    = double_int_to_tree (bitsizetype,
+                         tree_to_double_int (TYPE_MAX_VALUE (bitsizetype)));
 
   /* Create the signed variants of *sizetype.  */
   ssizetype = make_signed_type (TYPE_PRECISION (sizetype));
@@ -2361,6 +2367,13 @@ fixup_unsigned_type (tree type)
 /* Find the best machine mode to use when referencing a bit field of length
    BITSIZE bits starting at BITPOS.
 
+   BITREGION_START is the bit position of the first bit in this
+   sequence of bit fields.  BITREGION_END is the last bit in this
+   sequence.  If these two fields are non-zero, we should restrict the
+   memory access to a maximum sized chunk of
+   BITREGION_END - BITREGION_START + 1.  Otherwise, we are allowed to touch
+   any adjacent non bit-fields.
+
    The underlying object is known to be aligned to a boundary of ALIGN bits.
    If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
    larger than LARGEST_MODE (usually SImode).
@@ -2378,18 +2391,29 @@ fixup_unsigned_type (tree type)
    decide which of the above modes should be used.  */
 
 enum machine_mode
-get_best_mode (int bitsize, int bitpos, unsigned int align,
+get_best_mode (int bitsize, int bitpos,
+              unsigned HOST_WIDE_INT bitregion_start,
+              unsigned HOST_WIDE_INT bitregion_end,
+              unsigned int align,
               enum machine_mode largest_mode, int volatilep)
 {
   enum machine_mode mode;
   unsigned int unit = 0;
+  unsigned HOST_WIDE_INT maxbits;
+
+  /* If unset, no restriction.  */
+  if (!bitregion_end)
+    maxbits = MAX_FIXED_MODE_SIZE;
+  else
+    maxbits = (bitregion_end - bitregion_start) % align + 1;
 
   /* Find the narrowest integer mode that contains the bit field.  */
   for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
        mode = GET_MODE_WIDER_MODE (mode))
     {
       unit = GET_MODE_BITSIZE (mode);
-      if ((bitpos % unit) + bitsize <= unit)
+      if (unit == GET_MODE_PRECISION (mode)
+         && (bitpos % unit) + bitsize <= unit)
        break;
     }
 
@@ -2414,9 +2438,11 @@ get_best_mode (int bitsize, int bitpos, unsigned int align,
           tmode = GET_MODE_WIDER_MODE (tmode))
        {
          unit = GET_MODE_BITSIZE (tmode);
-         if (bitpos / unit == (bitpos + bitsize - 1) / unit
+         if (unit == GET_MODE_PRECISION (tmode)
+             && bitpos / unit == (bitpos + bitsize - 1) / unit
              && unit <= BITS_PER_WORD
              && unit <= MIN (align, BIGGEST_ALIGNMENT)
+             && unit <= maxbits
              && (largest_mode == VOIDmode
                  || unit <= GET_MODE_BITSIZE (largest_mode)))
            wide_mode = tmode;