[gcc r13-60] Denormalize VR_VARYING to VR_RANGE before passing it to set_range_info_raw.

[gcc r13-60] Denormalize VR_VARYING to VR_RANGE before passing it to set_range_info_raw.

[Aldy Hernandez]

https://gcc.gnu.org/g:75bbc3da3e5f75f683fa33e309045c582efd20eb

commit r13-60-g75bbc3da3e5f75f683fa33e309045c582efd20eb
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Fri Apr 29 22:46:25 2022 +0200

    Denormalize VR_VARYING to VR_RANGE before passing it to set_range_info_raw.
    
    We are ICEing in set_range_info_raw because value_range_kind cannot be
    VR_VARYING, since SSA_NAME_RANGE_TYPE can only hold VR_RANGE /
    VR_ANTI_RANGE.  Most of the time setting a VR_VARYING as a global
    range makes no sense.  However, we can have a range spanning the
    entire domain (VR_RANGE of [MIN,MAX] which is essentially a
    VR_VARYING), if the nonzero bits are set.
    
    This was working before because set_range_info_raw allows setting
    VR_RANGE of [MIN, MAX].  However, when going through an irange, we
    normalize this to a VR_VARYING, thus causing the ICE.  It's
    interesting that other calls to set_range_info with an irange haven't
    triggered this.
    
    One solution would be to just ignore VR_VARYING and bail, since
    set_range_info* is really an update of the current range semantic
    wise.  After all, we keep the nonzero bits which provide additional
    info.  But this would be a change in behavior, so not suitable until
    after GCC 12 is released.  So in order to keep with current behavior
    we can just denormalize the varying to VR_RANGE.
    
    Tested on x86-64 Linux.
    
                PR tree-optimization/105432
    
    gcc/ChangeLog:
    
            * tree-ssanames.cc (set_range_info): Denormalize VR_VARYING to
            VR_RANGE before passing a piecewise range to set_range_info_raw.

Diff:
---
 gcc/tree-ssanames.cc | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-ssanames.cc b/gcc/tree-ssanames.cc
index c957597af4f..05536cd2f74 100644
--- a/gcc/tree-ssanames.cc
+++ b/gcc/tree-ssanames.cc
@@ -395,8 +395,17 @@ set_range_info (tree name, enum value_range_kind range_type,
 {
   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 
-  /* A range of the entire domain is really no range at all.  */
   tree type = TREE_TYPE (name);
+  if (range_type == VR_VARYING)
+    {
+      /* SSA_NAME_RANGE_TYPE can only hold a VR_RANGE or
+	 VR_ANTI_RANGE.  Denormalize VR_VARYING to VR_RANGE.  */
+      range_type = VR_RANGE;
+      gcc_checking_assert (min == wi::min_value (type));
+      gcc_checking_assert (max == wi::max_value (type));
+    }
+
+  /* A range of the entire domain is really no range at all.  */
   if (min == wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type))
       && max == wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)))
     {