[gcc r13-2876] Set ranges from unreachable edges for all known ranges.

[gcc r13-2876] Set ranges from unreachable edges for all known ranges.

[Aldy Hernandez]

https://gcc.gnu.org/g:2460f7cdef7ef9c971de79271afc0db73687a272

commit r13-2876-g2460f7cdef7ef9c971de79271afc0db73687a272
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Fri Sep 23 19:47:33 2022 +0200

    Set ranges from unreachable edges for all known ranges.
    
    In the conversion of DOM+evrp to DOM+ranger, we missed that evrp was
    exporting ranges for unreachable edges for all SSA names for which we
    have ranges for.  Instead we have only been exporting ranges for the
    SSA name in the final conditional to the BB involving the unreachable
    edge.
    
    This patch adjusts adjusts DOM to iterate over the exports, similarly
    to what evrp was doing.
    
    Note that I also noticed that we don't calculate the nonzero bit mask
    for op1, when 0 = op1 & MASK.  This isn't needed for this PR,
    since maybe_set_nonzero_bits() is chasing the definition and
    parsing the bitwise and on its own.  However, I'll be adding the
    functionality for completeness sake, plus we could probably drop the
    maybe_set_nonzero_bits legacy call entirely.
    
            PR tree-optimization/107009
    
    gcc/ChangeLog:
    
            * tree-ssa-dom.cc
            (dom_opt_dom_walker::set_global_ranges_from_unreachable_edges):
            Iterate over exports.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/pr107009.c: New test.

Diff:
---
 gcc/testsuite/gcc.dg/tree-ssa/pr107009.c | 15 ++++++++++++++
 gcc/tree-ssa-dom.cc                      | 35 ++++++++++++++++----------------
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr107009.c b/gcc/testsuite/gcc.dg/tree-ssa/pr107009.c
new file mode 100644
index 00000000000..5010aed1723
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr107009.c
@@ -0,0 +1,15 @@
+// { dg-do compile }
+// { dg-options "-O2 -fdump-tree-dom2-alias" }
+
+typedef __SIZE_TYPE__ size_t;
+
+void saxpy(size_t n)
+{
+  if (n == 0 || n % 8 != 0)
+    __builtin_unreachable();
+
+  extern void foobar (size_t n);
+  foobar (n);
+}
+
+// { dg-final { scan-tree-dump "NONZERO.*fff8" "dom2" } }
diff --git a/gcc/tree-ssa-dom.cc b/gcc/tree-ssa-dom.cc
index 513e0c88254..84bef798f52 100644
--- a/gcc/tree-ssa-dom.cc
+++ b/gcc/tree-ssa-dom.cc
@@ -1227,29 +1227,30 @@ void
 dom_opt_dom_walker::set_global_ranges_from_unreachable_edges (basic_block bb)
 {
   edge pred_e = single_pred_edge_ignoring_loop_edges (bb, false);
-
   if (!pred_e)
     return;
 
   gimple *stmt = last_stmt (pred_e->src);
+  if (!stmt
+      || gimple_code (stmt) != GIMPLE_COND
+      || !assert_unreachable_fallthru_edge_p (pred_e))
+    return;
+
   tree name;
-  if (stmt
-      && gimple_code (stmt) == GIMPLE_COND
-      && (name = gimple_cond_lhs (stmt))
-      && TREE_CODE (name) == SSA_NAME
-      && assert_unreachable_fallthru_edge_p (pred_e)
-      && all_uses_feed_or_dominated_by_stmt (name, stmt))
-    {
-      Value_Range r (TREE_TYPE (name));
+  gori_compute &gori = m_ranger->gori ();
+  FOR_EACH_GORI_EXPORT_NAME (gori, pred_e->src, name)
+    if (all_uses_feed_or_dominated_by_stmt (name, stmt))
+      {
+	Value_Range r (TREE_TYPE (name));
 
-      if (m_ranger->range_on_edge (r, pred_e, name)
-	  && !r.varying_p ()
-	  && !r.undefined_p ())
-	{
-	  set_range_info (name, r);
-	  maybe_set_nonzero_bits (pred_e, name);
-	}
-    }
+	if (m_ranger->range_on_edge (r, pred_e, name)
+	    && !r.varying_p ()
+	    && !r.undefined_p ())
+	  {
+	    set_range_info (name, r);
+	    maybe_set_nonzero_bits (pred_e, name);
+	  }
+      }
 }
 
 /* Record any equivalences created by the incoming edge to BB into