[Bug middle-end/55142] [4.8 Regression] internal compiler error: in plus_constant, at explow.c:88

["hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55142

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> 2012-10-31 12:19:56 UTC ---
Does this make any senses?

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 5ea5110..50879d6 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7038,6 +7038,24 @@ fold_to_nonsharp_ineq_using_bound (location_t loc, tree
ineq, tree bound)
   return fold_build2_loc (loc, GE_EXPR, type, a, y);
 }

+static unsigned int
+unsigned_expr_operands (tree op)
+{
+  switch (TREE_CODE (op))
+    {
+    case MULT_EXPR:
+      if (!unsigned_expr_operands (TREE_OPERAND (op, 0)))
+    return 0;
+      return unsigned_expr_operands (TREE_OPERAND (op, 1));
+
+    case NOP_EXPR:
+      return unsigned_expr_operands (TREE_OPERAND (op, 0));
+
+    default:
+      return TYPE_UNSIGNED (TREE_TYPE (op));
+    }
+}
+
 /* Fold a sum or difference of at least one multiplication.
    Returns the folded tree or NULL if no simplification could be made.  */

@@ -7048,6 +7066,17 @@ fold_plusminus_mult_expr (location_t loc, enum tree_code
code, tree type,
   tree arg00, arg01, arg10, arg11;
   tree alt0 = NULL_TREE, alt1 = NULL_TREE, same;

+  /* Make sure the type is not saturating and has the signedness of
+     the stripped operands, as fold_plusminus_mult_expr will re-associate.
+     ??? The latter condition should use TYPE_OVERFLOW_* flags instead.  */
+  if (!((TREE_CODE (arg0) == MULT_EXPR
+       || TREE_CODE (arg1) == MULT_EXPR)
+      && !TYPE_SATURATING (type)
+      && TYPE_UNSIGNED (type) == unsigned_expr_operands (arg0)
+      && TYPE_UNSIGNED (type) == unsigned_expr_operands (arg1)
+      && (!FLOAT_TYPE_P (type) || flag_associative_math)))
+    return NULL_TREE;
+
   /* (A * C) +- (B * C) -> (A+-B) * C.
      (A * C) +- A -> A * (C+-1).
      We are most concerned about the case where C is a constant,
@@ -10042,17 +10071,7 @@ fold_binary_loc (location_t loc,
         }
     }

-      /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
-     one.  Make sure the type is not saturating and has the signedness of
-     the stripped operands, as fold_plusminus_mult_expr will re-associate.
-     ??? The latter condition should use TYPE_OVERFLOW_* flags instead.  */
-      if ((TREE_CODE (arg0) == MULT_EXPR
-       || TREE_CODE (arg1) == MULT_EXPR)
-      && !TYPE_SATURATING (type)
-      && TYPE_UNSIGNED (type) == TYPE_UNSIGNED (TREE_TYPE (arg0))
-      && TYPE_UNSIGNED (type) == TYPE_UNSIGNED (TREE_TYPE (arg1))
-      && (!FLOAT_TYPE_P (type) || flag_associative_math))
-        {
+    {
       tree tem = fold_plusminus_mult_expr (loc, code, type, arg0, arg1);
       if (tem)
         return tem;
@@ -10668,17 +10687,7 @@ fold_binary_loc (location_t loc,
       && (tem = distribute_real_division (loc, code, type, arg0, arg1)))
     return tem;

-      /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
-     one.  Make sure the type is not saturating and has the signedness of
-     the stripped operands, as fold_plusminus_mult_expr will re-associate.
-     ??? The latter condition should use TYPE_OVERFLOW_* flags instead.  */
-      if ((TREE_CODE (arg0) == MULT_EXPR
-       || TREE_CODE (arg1) == MULT_EXPR)
-      && !TYPE_SATURATING (type)
-      && TYPE_UNSIGNED (type) == TYPE_UNSIGNED (TREE_TYPE (arg0))
-      && TYPE_UNSIGNED (type) == TYPE_UNSIGNED (TREE_TYPE (arg1))
-      && (!FLOAT_TYPE_P (type) || flag_associative_math))
-        {
+    {
       tree tem = fold_plusminus_mult_expr (loc, code, type, arg0, arg1);
       if (tem)
         return tem;