Re: [patch] Fix PHI optimization issue with boolean types

[Eric Botcazou]

> > But integer_truep is just integer_onep for BOOLEAN_TYPEs.
> 
> Yes, but it's more descriptive IMHO.

At the cost of consistency with fits_to_tree_p though.

> fits_to_tree_p avoids creating an INTEGER_CST in ggc memory and thus is the
> prefered way to test if you have a wide-int but not yet an INTEGER_CST.

OK, I was confused by int_fits_type_p, which calls it on an INTEGER_CST (which 
now breaks with the additional test in the function).

The attached fix seems to work and passes regression testing (all languages).


        * tree.h (wi::fits_to_tree_p): Accept only 0 and 1 for boolean types.
        * tree.c (int_fits_type_p): Likewise.  Pass the integer constant as a
        widest_int to above.

-- 
Eric Botcazou
Index: tree.c
===================================================================
--- tree.c	(revision 241437)
+++ tree.c	(working copy)
@@ -9065,8 +9065,8 @@ get_narrower (tree op, int *unsignedp_pt
   return win;
 }
 
-/* Returns true if integer constant C has a value that is permissible
-   for type TYPE (an INTEGER_TYPE).  */
+/* Return true if integer constant C has a value that is permissible
+   for TYPE, an integral type.  */
 
 bool
 int_fits_type_p (const_tree c, const_tree type)
@@ -9075,6 +9075,11 @@ int_fits_type_p (const_tree c, const_tre
   bool ok_for_low_bound, ok_for_high_bound;
   signop sgn_c = TYPE_SIGN (TREE_TYPE (c));
 
+  /* Short-circuit boolean types since various transformations assume that
+     they can only take values 0 and 1.  */
+  if (TREE_CODE (type) == BOOLEAN_TYPE)
+    return integer_zerop (c) || integer_truep (c);
+
 retry:
   type_low_bound = TYPE_MIN_VALUE (type);
   type_high_bound = TYPE_MAX_VALUE (type);
@@ -9154,7 +9159,7 @@ retry:
     }
 
   /* Or to fits_to_tree_p, if nothing else.  */
-  return wi::fits_to_tree_p (c, type);
+  return wi::fits_to_tree_p (wi::to_widest (c), type);
 }
 
 /* Stores bounds of an integer TYPE in MIN and MAX.  If TYPE has non-constant
Index: tree.h
===================================================================
--- tree.h	(revision 241437)
+++ tree.h	(working copy)
@@ -5295,6 +5295,11 @@ template <typename T>
 bool
 wi::fits_to_tree_p (const T &x, const_tree type)
 {
+  /* Short-circuit boolean types since various transformations assume that
+     they can only take values 0 and 1.  */
+  if (TREE_CODE (type) == BOOLEAN_TYPE)
+    return x == 0 || x == 1;
+
   if (TYPE_SIGN (type) == UNSIGNED)
     return eq_p (x, zext (x, TYPE_PRECISION (type)));
   else