Fix volatile issues in optimize_bit_field_compare.

2013-10-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        Fix volatile issues in optimize_bit_field_compare.
        * fold-const.c (optimize_bit_field_compare): Bail out if
        lvolatilep or rvolatilep.

From-SVN: r203899

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fd9123f6ae0cb75a03edbe1b5b1715f68ca06ab7..e839517732c14b0f8e51d03cbc310c89b3c8461b 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2013-10-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+       Fix volatile issues in optimize_bit_field_compare.
+       * fold-const.c (optimize_bit_field_compare): Bail out if
+       lvolatilep or rvolatilep.
+
 2013-10-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
        Fix DECL_BIT_FIELD depencency on flag_strict_volatile_bitfields

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 0f9454d4be6e6904e0e40f28a46383bec246d15d..2c2b929d6e296d4d4f23508e70c773bbbd86ab64 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -3473,11 +3473,6 @@ optimize_bit_field_compare (location_t loc, enum tree_code code,
   tree mask;
   tree offset;
 
-  /* In the strict volatile bitfields case, doing code changes here may prevent
-     other optimizations, in particular in a SLOW_BYTE_ACCESS setting.  */
-  if (flag_strict_volatile_bitfields > 0)
-    return 0;
-
   /* Get all the information about the extractions being done.  If the bit size
      if the same as the size of the underlying object, we aren't doing an
      extraction at all and so can do nothing.  We also don't want to
@@ -3486,7 +3481,7 @@ optimize_bit_field_compare (location_t loc, enum tree_code code,
   linner = get_inner_reference (lhs, &lbitsize, &lbitpos, &offset, &lmode,
                                &lunsignedp, &lvolatilep, false);
   if (linner == lhs || lbitsize == GET_MODE_BITSIZE (lmode) || lbitsize < 0
-      || offset != 0 || TREE_CODE (linner) == PLACEHOLDER_EXPR)
+      || offset != 0 || TREE_CODE (linner) == PLACEHOLDER_EXPR || lvolatilep)
     return 0;
 
  if (!const_p)
@@ -3498,22 +3493,17 @@ optimize_bit_field_compare (location_t loc, enum tree_code code,
 
      if (rinner == rhs || lbitpos != rbitpos || lbitsize != rbitsize
         || lunsignedp != runsignedp || offset != 0
-        || TREE_CODE (rinner) == PLACEHOLDER_EXPR)
+        || TREE_CODE (rinner) == PLACEHOLDER_EXPR || rvolatilep)
        return 0;
    }
 
   /* See if we can find a mode to refer to this field.  We should be able to,
      but fail if we can't.  */
-  if (lvolatilep
-      && GET_MODE_BITSIZE (lmode) > 0
-      && flag_strict_volatile_bitfields > 0)
-    nmode = lmode;
-  else
-    nmode = get_best_mode (lbitsize, lbitpos, 0, 0,
-                          const_p ? TYPE_ALIGN (TREE_TYPE (linner))
-                          : MIN (TYPE_ALIGN (TREE_TYPE (linner)),
-                                 TYPE_ALIGN (TREE_TYPE (rinner))),
-                          word_mode, lvolatilep || rvolatilep);
+  nmode = get_best_mode (lbitsize, lbitpos, 0, 0,
+                        const_p ? TYPE_ALIGN (TREE_TYPE (linner))
+                        : MIN (TYPE_ALIGN (TREE_TYPE (linner)),
+                               TYPE_ALIGN (TREE_TYPE (rinner))),
+                        word_mode, false);
   if (nmode == VOIDmode)
     return 0;
 
@@ -3602,11 +3592,6 @@ optimize_bit_field_compare (location_t loc, enum tree_code code,
      appropriate number of bits and mask it with the computed mask
      (in case this was a signed field).  If we changed it, make a new one.  */
   lhs = make_bit_field_ref (loc, linner, unsigned_type, nbitsize, nbitpos, 1);
-  if (lvolatilep)
-    {
-      TREE_SIDE_EFFECTS (lhs) = 1;
-      TREE_THIS_VOLATILE (lhs) = 1;
-    }
 
   rhs = const_binop (BIT_AND_EXPR,
                     const_binop (LSHIFT_EXPR,