[PATCH][2/2] Get TREE_OVERFLOW somewhat under control

[Richard Biener]

This fixes CCP and DOM to not spread TREE_OVERFLOW eventually set
from fold.  I've chosen to change the lattice updating which is
easiest.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2013-11-07  Richard Biener  <rguenther@suse.de>

	* tree-ssa-ccp.c (canonicalize_float_value): Rename to ...
	(canonicalize_value): ... this.  Also handle stripping of
	TREE_OVERFLOW.
	(get_value, set_lattice_value, get_value_for_expr): Adjust.
	* gimple-fold.c (canonicalize_constructor_val): Strip
	TREE_OVERFLOW.
	* tree-ssa-threadedge.c (set_ssa_name_value): Likewise.

Index: gcc/tree-ssa-ccp.c
===================================================================
--- gcc/tree-ssa-ccp.c	(revision 204504)
+++ gcc/tree-ssa-ccp.c	(working copy)
@@ -168,7 +168,7 @@ typedef struct prop_value_d prop_value_t
 static prop_value_t *const_val;
 static unsigned n_const_val;
 
-static void canonicalize_float_value (prop_value_t *);
+static void canonicalize_value (prop_value_t *);
 static bool ccp_fold_stmt (gimple_stmt_iterator *);
 
 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX.  */
@@ -326,7 +326,7 @@ get_value (tree var)
   if (val->lattice_val == UNINITIALIZED)
     *val = get_default_value (var);
 
-  canonicalize_float_value (val);
+  canonicalize_value (val);
 
   return val;
 }
@@ -378,17 +378,24 @@ set_value_varying (tree var)
      that HONOR_NANS is false, and we try to change the value of x to 0,
      causing an ICE.  With HONOR_NANS being false, the real appearance of
      NaN would cause undefined behavior, though, so claiming that y (and x)
-     are UNDEFINED initially is correct.  */
+     are UNDEFINED initially is correct.
+
+  For other constants, make sure to drop TREE_OVERFLOW.  */
 
 static void
-canonicalize_float_value (prop_value_t *val)
+canonicalize_value (prop_value_t *val)
 {
   enum machine_mode mode;
   tree type;
   REAL_VALUE_TYPE d;
 
-  if (val->lattice_val != CONSTANT
-      || TREE_CODE (val->value) != REAL_CST)
+  if (val->lattice_val != CONSTANT)
+    return;
+
+  if (TREE_OVERFLOW_P (val->value))
+    val->value = drop_tree_overflow (val->value);
+
+  if (TREE_CODE (val->value) != REAL_CST)
     return;
 
   d = TREE_REAL_CST (val->value);
@@ -454,7 +461,7 @@ set_lattice_value (tree var, prop_value_
   /* We can deal with old UNINITIALIZED values just fine here.  */
   prop_value_t *old_val = &const_val[SSA_NAME_VERSION (var)];
 
-  canonicalize_float_value (&new_val);
+  canonicalize_value (&new_val);
 
   /* We have to be careful to not go up the bitwise lattice
      represented by the mask.
@@ -569,7 +576,7 @@ get_value_for_expr (tree expr, bool for_
       val.lattice_val = CONSTANT;
       val.value = expr;
       val.mask = double_int_zero;
-      canonicalize_float_value (&val);
+      canonicalize_value (&val);
     }
   else if (TREE_CODE (expr) == ADDR_EXPR)
     val = get_value_from_alignment (expr);
Index: gcc/gimple-fold.c
===================================================================
--- gcc/gimple-fold.c	(revision 204504)
+++ gcc/gimple-fold.c	(working copy)
@@ -205,6 +205,8 @@ canonicalize_constructor_val (tree cval,
 	cval = fold_convert (TREE_TYPE (orig_cval), cval);
       return cval;
     }
+  if (TREE_OVERFLOW_P (cval))
+    return drop_tree_overflow (cval);
   return orig_cval;
 }
 
Index: gcc/tree-ssa-threadedge.c
===================================================================
--- gcc/tree-ssa-threadedge.c	(revision 204504)
+++ gcc/tree-ssa-threadedge.c	(working copy)
@@ -58,6 +58,8 @@ set_ssa_name_value (tree name, tree valu
 {
   if (SSA_NAME_VERSION (name) >= ssa_name_values.length ())
     ssa_name_values.safe_grow_cleared (SSA_NAME_VERSION (name) + 1);
+  if (value && TREE_OVERFLOW_P (value))
+    value = drop_tree_overflow (value);
   ssa_name_values[SSA_NAME_VERSION (name)] = value;
 }