tree-ssanames: Allow non-SSA_NAME arguments to get_range_info

My recent match.pd change required quite a lot of code due to the separate
need to handle INTEGER_CSTs and SSA_NAMEs, and after all, I didn't even
handle one case there, when in x * y / y the x is INTEGER_CST and y is
SSA_NAME.
The following patch allows to simplify it, by allowing non-SSA_NAME argument
to get_range_info, for INTEGER_CSTs it will return VR_RANGE with *min == *max
equal to the constnat, and for non-INTEGER_CST/SSA_NAMEs it will just return
VR_VARYING.

This allows not to simplify just the match.pd, but some other spots too.

2020-11-27  Jakub Jelinek  <jakub@redhat.com>

	* tree-ssanames.c (get_range_info): Handle INTEGER_CST by returning
	VR_RANGE with both *min and *max set to the wide_int value of the
	INTEGER_CST.  Return VR_VARYING for non-SSA_NAMEs.
	* match.pd ((t * 2) / 2) -> t): Handle also @0 being INTEGER_CST.
	Simplify by calling get_range_info on everything.
	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Simplify by calling
	get_range_info on everything.
	* tree-scalar-evolution.c (iv_can_overflow_p): Likewise.

1 files changed, 14 insertions, 5 deletions

diff --git a/gcc/tree-ssanames.c b/gcc/tree-ssanames.c
index ec4681f..1b9dcec 100644
--- a/gcc/tree-ssanames.c
+++ b/gcc/tree-ssanames.c
@@ -420,21 +420,30 @@ set_range_info (tree name, const value_range &vr)
    is used to determine if MIN and MAX are valid values.  */
 
 enum value_range_kind
-get_range_info (const_tree name, wide_int *min, wide_int *max)
+get_range_info (const_tree expr, wide_int *min, wide_int *max)
 {
-  gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
+  gcc_assert (!POINTER_TYPE_P (TREE_TYPE (expr)));
   gcc_assert (min && max);
-  range_info_def *ri = SSA_NAME_RANGE_INFO (name);
+  if (TREE_CODE (expr) == INTEGER_CST)
+    {
+      *min = wi::to_wide (expr);
+      *max = *min;
+      return VR_RANGE;
+    }
+  if (TREE_CODE (expr) != SSA_NAME)
+    return VR_VARYING;
+
+  range_info_def *ri = SSA_NAME_RANGE_INFO (expr);
 
   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
-  if (!ri || (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (TREE_TYPE (name)))
+  if (!ri || (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (TREE_TYPE (expr)))
 	      > 2 * HOST_BITS_PER_WIDE_INT))
     return VR_VARYING;
 
   *min = ri->get_min ();
   *max = ri->get_max ();
-  return SSA_NAME_RANGE_TYPE (name);
+  return SSA_NAME_RANGE_TYPE (expr);
 }
 
 /* Gets range information corresponding to ssa_name NAME and stores it