Fix PR47576 and PR47555: add PARAM_SCEV_MAX_EXPR_COMPLEXITY.

2011-02-02  Sebastian Pop  <sebastian.pop@amd.com>

	PR tree-optimization/47576
	PR tree-optimization/47555
	* doc/invoke.texi (scev-max-expr-complexity): Documented.
	* params.def (PARAM_SCEV_MAX_EXPR_SIZE): Bump the value to 100.
	(PARAM_SCEV_MAX_EXPR_COMPLEXITY): Declared.
	* tree-scalar-evolution.c (follow_ssa_edge): Use
	PARAM_SCEV_MAX_EXPR_COMPLEXITY.

From-SVN: r169530

gcc/ChangeLog

+2011-02-02  Sebastian Pop  <sebastian.pop@amd.com>
+
+	PR tree-optimization/47576
+	PR tree-optimization/47555
+	* doc/invoke.texi (scev-max-expr-complexity): Documented.
+	* params.def (PARAM_SCEV_MAX_EXPR_SIZE): Bump the value to 100.
+	(PARAM_SCEV_MAX_EXPR_COMPLEXITY): Declared.
+	* tree-scalar-evolution.c (follow_ssa_edge): Use
+	PARAM_SCEV_MAX_EXPR_COMPLEXITY.
+
 2011-02-02  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/47566

gcc/doc/invoke.texi

@@ -8463,6 +8463,10 @@ optimization when a new iv is added to the set.
 Bound on size of expressions used in the scalar evolutions analyzer.
 Large expressions slow the analyzer.
 
+@item scev-max-expr-complexity
+Bound on the complexity of the expressions in the scalar evolutions analyzer.
+Complex expressions slow the analyzer.
+
 @item omega-max-vars
 The maximum number of variables in an Omega constraint system.
 The default value is 128.

gcc/params.def

@@ -481,7 +481,12 @@ DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
 DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
  	 "scev-max-expr-size",
 	 "Bound on size of expressions used in the scalar evolutions analyzer",
-	 20, 0, 0)
+	 100, 0, 0)
+
+DEFPARAM(PARAM_SCEV_MAX_EXPR_COMPLEXITY,
+	 "scev-max-expr-complexity",
+	 "Bound on the complexity of the expressions in the scalar evolutions analyzer",
+	 10, 0, 0)
 
 DEFPARAM(PARAM_OMEGA_MAX_VARS,
  	 "omega-max-vars",

gcc/tree-scalar-evolution.c

@@ -1399,7 +1399,7 @@ follow_ssa_edge (struct loop *loop, gimple def, gimple halting_phi,
     return t_false;
 
   /* Give up if the path is longer than the MAX that we allow.  */
-  if (limit > PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
+  if (limit > PARAM_VALUE (PARAM_SCEV_MAX_EXPR_COMPLEXITY))
     return t_dont_know;
 
   def_loop = loop_containing_stmt (def);