re PR tree-optimization/18463 (suboptimal use of fancy x86 addressing modes)

	PR tree-optimization/18463
	* tree-chrec.c (chrec_convert): Return fold_converted chrec if
	converting it directly is not possible.
	(chrec_convert_aggressive): New function.
	* tree-chrec.h (chrec_convert_aggressive): Declare.
	* tree-scalar-evolution.c (instantiate_parameters_1, resolve_mixers):
	Fold chrec conversions aggressively if asked to.
	(instantiate_parameters): Modified because of changes in
	instantiate_parameters_1.

From-SVN: r104443

gcc/ChangeLog

+2005-09-20  Zdenek Dvorak  <dvorakz@suse.cz>
+
+	PR tree-optimization/18463
+	* tree-chrec.c (chrec_convert): Return fold_converted chrec if
+	converting it directly is not possible.
+	(chrec_convert_aggressive): New function.
+	* tree-chrec.h (chrec_convert_aggressive): Declare.
+	* tree-scalar-evolution.c (instantiate_parameters_1, resolve_mixers):
+	Fold chrec conversions aggressively if asked to.
+	(instantiate_parameters): Modified because of changes in
+	instantiate_parameters_1.
+
 2005-09-19  Richard Henderson  <rth@redhat.com>
 
 	* config/i386/sse.md (reduc_splus_v4sf): Rename from reduc_plus_v4sf.

gcc/tree-chrec.c

@@ -1164,9 +1164,7 @@ chrec_convert (tree type, tree chrec, tree at_stmt)
 	      fprintf (dump_file, "\n)\n");
 	    }
 
-	  /* Directly convert to "don't know": no worth dealing with
-	     difficult cases.  */
-	  return chrec_dont_know;
+	  return fold_convert (type, chrec);
 	}
 
       return build_polynomial_chrec (CHREC_VARIABLE (chrec),
@@ -1201,6 +1199,35 @@ chrec_convert (tree type, tree chrec, tree at_stmt)
   return res;
 }
 
+/* Convert CHREC to TYPE, without regard to signed overflows.  Returns the new
+   chrec if something else than what chrec_convert would do happens, NULL_TREE
+   otherwise.  */
+
+tree
+chrec_convert_aggressive (tree type, tree chrec)
+{
+  tree inner_type, left, right, lc, rc;
+
+  if (automatically_generated_chrec_p (chrec)
+      || TREE_CODE (chrec) != POLYNOMIAL_CHREC)
+    return NULL_TREE;
+
+  inner_type = TREE_TYPE (chrec);
+  if (TYPE_PRECISION (type) > TYPE_PRECISION (inner_type))
+    return NULL_TREE;
+
+  left = CHREC_LEFT (chrec);
+  right = CHREC_RIGHT (chrec);
+  lc = chrec_convert_aggressive (type, left);
+  if (!lc)
+    lc = chrec_convert (type, left, NULL_TREE);
+  rc = chrec_convert_aggressive (type, right);
+  if (!rc)
+    rc = chrec_convert (type, right, NULL_TREE);
+
+  return build_polynomial_chrec (CHREC_VARIABLE (chrec), lc, rc);
+}
+
 /* Returns the type of the chrec.  */
 
 tree 

gcc/tree-chrec.h

@@ -68,6 +68,7 @@ extern tree chrec_fold_plus (tree, tree, tree);
 extern tree chrec_fold_minus (tree, tree, tree);
 extern tree chrec_fold_multiply (tree, tree, tree);
 extern tree chrec_convert (tree, tree, tree);
+extern tree chrec_convert_aggressive (tree, tree);
 extern tree chrec_type (tree);
 
 /* Operations.  */

gcc/tree-scalar-evolution.c

@@ -1955,20 +1955,27 @@ loop_closed_phi_def (tree var)
 }
 
 /* Analyze all the parameters of the chrec that were left under a symbolic form,
-   with respect to LOOP.  CHREC is the chrec to instantiate.  If
-   ALLOW_SUPERLOOP_CHRECS is true, replacing loop invariants with
-   outer loop chrecs is done.  CACHE is the cache of already instantiated
-   values.  */
+   with respect to LOOP.  CHREC is the chrec to instantiate.  CACHE is the cache
+   of already instantiated values.  FLAGS modify the way chrecs are
+   instantiated.  */
 
+/* Values for FLAGS.  */
+enum
+{
+  INSERT_SUPERLOOP_CHRECS = 1,  /* Loop invariants are replaced with chrecs
+				   in outer loops.  */
+  FOLD_CONVERSIONS = 2		/* The conversions that may wrap in
+				   signed/pointer type are folded, as long as the
+				   value of the chrec is preserved.  */
+};
+  
 static tree
-instantiate_parameters_1 (struct loop *loop, tree chrec,
-			  bool allow_superloop_chrecs,
-			  htab_t cache)
+instantiate_parameters_1 (struct loop *loop, tree chrec, int flags, htab_t cache)
 {
   tree res, op0, op1, op2;
   basic_block def_bb;
   struct loop *def_loop;
- 
+
   if (automatically_generated_chrec_p (chrec)
       || is_gimple_min_invariant (chrec))
     return chrec;
@@ -1981,7 +1988,7 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
       /* A parameter (or loop invariant and we do not want to include
 	 evolutions in outer loops), nothing to do.  */
       if (!def_bb
-	  || (!allow_superloop_chrecs
+	  || (!(flags & INSERT_SUPERLOOP_CHRECS)
 	      && !flow_bb_inside_loop_p (loop, def_bb)))
 	return chrec;
 
@@ -2036,8 +2043,7 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 	}
 
       else if (res != chrec_dont_know)
-	res = instantiate_parameters_1 (loop, res, allow_superloop_chrecs,
-					cache);
+	res = instantiate_parameters_1 (loop, res, flags, cache);
 
       bitmap_clear_bit (already_instantiated, SSA_NAME_VERSION (chrec));
 
@@ -2047,12 +2053,12 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 
     case POLYNOMIAL_CHREC:
       op0 = instantiate_parameters_1 (loop, CHREC_LEFT (chrec),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
 	return chrec_dont_know;
 
       op1 = instantiate_parameters_1 (loop, CHREC_RIGHT (chrec),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op1 == chrec_dont_know)
 	return chrec_dont_know;
 
@@ -2063,12 +2069,12 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 
     case PLUS_EXPR:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
 	return chrec_dont_know;
 
       op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op1 == chrec_dont_know)
 	return chrec_dont_know;
 
@@ -2079,12 +2085,12 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 
     case MINUS_EXPR:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
 	return chrec_dont_know;
 
       op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op1 == chrec_dont_know)
 	return chrec_dont_know;
 
@@ -2095,12 +2101,12 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 
     case MULT_EXPR:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
 	return chrec_dont_know;
 
       op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op1 == chrec_dont_know)
 	return chrec_dont_know;
 
@@ -2113,10 +2119,17 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
     case CONVERT_EXPR:
     case NON_LVALUE_EXPR:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
         return chrec_dont_know;
 
+      if (flags & FOLD_CONVERSIONS)
+	{
+	  tree tmp = chrec_convert_aggressive (TREE_TYPE (chrec), op0);
+	  if (tmp)
+	    return tmp;
+	}
+
       if (op0 == TREE_OPERAND (chrec, 0))
 	return chrec;
 
@@ -2136,17 +2149,17 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
     {
     case 3:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
 	return chrec_dont_know;
 
       op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op1 == chrec_dont_know)
 	return chrec_dont_know;
 
       op2 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 2),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op2 == chrec_dont_know)
         return chrec_dont_know;
 
@@ -2160,12 +2173,12 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 
     case 2:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
 	return chrec_dont_know;
 
       op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op1 == chrec_dont_know)
         return chrec_dont_know;
 
@@ -2176,7 +2189,7 @@ instantiate_parameters_1 (struct loop *loop, tree chrec,
 	    
     case 1:
       op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0),
-				      allow_superloop_chrecs, cache);
+				      flags, cache);
       if (op0 == chrec_dont_know)
         return chrec_dont_know;
       if (op0 == TREE_OPERAND (chrec, 0))
@@ -2214,7 +2227,7 @@ instantiate_parameters (struct loop *loop,
       fprintf (dump_file, ")\n");
     }
  
-  res = instantiate_parameters_1 (loop, chrec, true, cache);
+  res = instantiate_parameters_1 (loop, chrec, INSERT_SUPERLOOP_CHRECS, cache);
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
@@ -2229,13 +2242,15 @@ instantiate_parameters (struct loop *loop,
 }
 
 /* Similar to instantiate_parameters, but does not introduce the
-   evolutions in outer loops for LOOP invariants in CHREC.  */
+   evolutions in outer loops for LOOP invariants in CHREC, and does not
+   care about causing overflows, as long as they do not affect value
+   of an expression.  */
 
 static tree
 resolve_mixers (struct loop *loop, tree chrec)
 {
   htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info);
-  tree ret = instantiate_parameters_1 (loop, chrec, false, cache);
+  tree ret = instantiate_parameters_1 (loop, chrec, FOLD_CONVERSIONS, cache);
   htab_delete (cache);
   return ret;
 }