+2005-02-26 Zdenek Dvorak <dvorakz@suse.cz>
+
+ * tree-ssa-dom.c (simple_iv_increment_p): New function.
+ (simplify_rhs_and_lookup_avail_expr, eliminate_redundant_computations):
+ Do not propagate value of iv before increment over the increment.
+
2005-02-25 Joseph S. Myers <joseph@codesourcery.com>
* c-parser.c: New file.
2005-02-25 Zdenek Dvorak <dvorakz@suse.cz>
- * tree-ssa-dom.c (simple_iv_increment_p): New function.
- (simplify_rhs_and_lookup_avail_expr, eliminate_redundant_computations):
- Do not propagate value of iv before increment over the increment.
-
-2005-02-25 Zdenek Dvorak <dvorakz@suse.cz>
-
PR tree-optimization/19937
* tree-ssa-loop-ivopts.c (rewrite_use_compare): Cast the final value
to the type of the induction variable.
&& FLOAT_TYPE_P (TREE_TYPE (exp)));
}
+/* Returns true when STMT is a simple iv increment. It detects the
+ following situation:
+
+ i_1 = phi (..., i_2)
+ i_2 = i_1 +/- ... */
+
+static bool
+simple_iv_increment_p (tree stmt)
+{
+ tree lhs, rhs, preinc, phi;
+ unsigned i;
+
+ if (TREE_CODE (stmt) != MODIFY_EXPR)
+ return false;
+
+ lhs = TREE_OPERAND (stmt, 0);
+ if (TREE_CODE (lhs) != SSA_NAME)
+ return false;
+
+ rhs = TREE_OPERAND (stmt, 1);
+
+ if (TREE_CODE (rhs) != PLUS_EXPR
+ && TREE_CODE (rhs) != MINUS_EXPR)
+ return false;
+
+ preinc = TREE_OPERAND (rhs, 0);
+ if (TREE_CODE (preinc) != SSA_NAME)
+ return false;
+
+ phi = SSA_NAME_DEF_STMT (preinc);
+ if (TREE_CODE (phi) != PHI_NODE)
+ return false;
+
+ for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
+ if (PHI_ARG_DEF (phi, i) == lhs)
+ return true;
+
+ return false;
+}
+
/* STMT is a MODIFY_EXPR for which we were unable to find RHS in the
hash tables. Try to simplify the RHS using whatever equivalences
we may have recorded.
{
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
+ /* If the statement defines an induction variable, do not propagate
+ its value, so that we do not create overlapping life ranges. */
+ if (simple_iv_increment_p (rhs_def_stmt))
+ goto dont_fold_assoc;
+
/* See if the RHS_DEF_STMT has the same form as our statement. */
if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR)
{
|| ! def
|| TREE_CODE (def) != SSA_NAME
|| SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def)
- || NUM_V_MAY_DEFS (v_may_defs) != 0)
+ || NUM_V_MAY_DEFS (v_may_defs) != 0
+ /* Do not record equivalences for increments of ivs. This would create
+ overlapping live ranges for a very questionable gain. */
+ || simple_iv_increment_p (stmt))
insert = false;
/* Check if the expression has been computed before. */