re PR tree-optimization/46562 (CCP currently needs iteration for &a[i])

2011-03-24  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/46562
	* tree.c (build_invariant_address): New function.
	* tree.h (build_invariant_address): Declare.
	* tree-dfa.c (get_addr_base_and_unit_offset): Wrap around
	a renamed function moved ...
	* tree-flow-inline.h (get_addr_base_and_unit_offset_1): ... here.
	Take valueization callback parameter.
	* tree-flow.h (gimple_fold_stmt_to_constant): Declare.
	* gimple-fold.h: New file.
	* tree-ssa-ccp.c (ccp_fold): Use gimple_fold_stmt_to_constant_1.
	(ccp_fold, fold_const_aggregate_ref,
	fold_ctor_reference, fold_nonarray_ctor_reference,
	fold_array_ctor_reference, fold_string_cst_ctor_reference,
	get_base_constructor): Move ...
	* gimple-fold.c: ... here.
	(gimple_fold_stmt_to_constant_1): New function
	split out from ccp_fold.  Take a valueization callback parameter.
	Valueize all operands.
	(gimple_fold_stmt_to_constant): New wrapper function.
	(fold_const_aggregate_ref_1): New function split out from
	fold_const_aggregate_ref.  Take a valueization callback parameter.
	(fold_const_aggregate_ref): Wrap fold_const_aggregate_ref_1.
	* tree-ssa-sccvn.c (simplify_binary_expression): Simplify
	invariant POINTER_PLUS_EXPRs to invariant form.
	(vn_valueize): New function.
	(try_to_simplify): Simplify by using gimple_fold_stmt_to_constant.
	* tree-vrp.c (vrp_valueize): New function.
	(vrp_visit_assignment_or_call): Use gimple_fold_stmt_to_constant
	to fold statements to constants.
	* tree-ssa-pre.c (eliminate): Properly guard propagation of
	function declarations.
	* Makefile.in (tree-ssa-sccvn.o, tree-vrp.o, gimple-fold.o,
	tree-ssa-ccp.o): Add gimple-fold.h dependencies.

	* c-c++-common/pr46562-2.c: New testcase.
	* c-c++-common/pr46562.c: Likewise.

From-SVN: r171386

1 files changed, 22 insertions, 2 deletions

diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 42ea910..466c3a0 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-scalar-evolution.h"
 #include "tree-ssa-propagate.h"
 #include "tree-chrec.h"
+#include "gimple-fold.h"
 
 
 /* Type of value ranges.  See value_range_d for a description of these
@@ -5614,6 +5615,21 @@ vrp_initialize (void)
     }
 }
 
+/* Return the singleton value-range for NAME or NAME.  */
+
+static inline tree
+vrp_valueize (tree name)
+{
+  if (TREE_CODE (name) == SSA_NAME)
+    {
+      value_range_t *vr = get_value_range (name);
+      if (vr->type == VR_RANGE
+	  && (vr->min == vr->max
+	      || operand_equal_p (vr->min, vr->max, 0)))
+	return vr->min;
+    }
+  return name;
+}
 
 /* Visit assignment STMT.  If it produces an interesting range, record
    the SSA name in *OUTPUT_P.  */
@@ -5637,7 +5653,12 @@ vrp_visit_assignment_or_call (gimple stmt, tree *output_p)
     {
       value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL };
 
-      if (code == GIMPLE_CALL)
+      /* Try folding the statement to a constant first.  */
+      tree tem = gimple_fold_stmt_to_constant (stmt, vrp_valueize);
+      if (tem && !is_overflow_infinity (tem))
+	set_value_range (&new_vr, VR_RANGE, tem, tem, NULL);
+      /* Then dispatch to value-range extracting functions.  */
+      else if (code == GIMPLE_CALL)
 	extract_range_basic (&new_vr, stmt);
       else
 	extract_range_from_assignment (&new_vr, stmt);
@@ -6366,7 +6387,6 @@ vrp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p)
       /* In general, assignments with virtual operands are not useful
 	 for deriving ranges, with the obvious exception of calls to
 	 builtin functions.  */
-
       if ((is_gimple_call (stmt)
 	   && gimple_call_fndecl (stmt) != NULL_TREE
 	   && DECL_IS_BUILTIN (gimple_call_fndecl (stmt)))