[gcc r12-5628] Always track arguments, even when ignoring equiv params.

[Andrew Macleod <amacleod@gcc.gnu.org>]

https://gcc.gnu.org/g:e43b15c88c242b14a8ced8e631c1f9b80e83d63c

commit r12-5628-ge43b15c88c242b14a8ced8e631c1f9b80e83d63c
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Mon Nov 29 09:19:34 2021 -0500

    Always track arguments, even when ignoring equiv params.
    
    To "ignore" ranges from equivalences, we should track the range separately,
    but still do the other name processing which determiens if there is a single
    name or not for equivalence.  Otherwise we mistakently think we can introduce
    an equivalences.
    
            gcc/
            PR tree-optimization/103440
            * gimple-range-fold.cc (fold_using_range::range_of_phi): Continue
            normal param processing for equiv params.
    
            gcc/testsuite/
            * gcc.dg/pr103440.c: New.

Diff:
---
 gcc/gimple-range-fold.cc        | 21 +++++++++------------
 gcc/testsuite/gcc.dg/pr103440.c | 24 ++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/gcc/gimple-range-fold.cc b/gcc/gimple-range-fold.cc
index d66ada5bb7c..58122297c0b 100644
--- a/gcc/gimple-range-fold.cc
+++ b/gcc/gimple-range-fold.cc
@@ -795,20 +795,17 @@ fold_using_range::range_of_phi (irange &r, gphi *phi, fur_source &src)
       // Get the range of the argument on its edge.
       src.get_phi_operand (arg_range, arg, e);
 
-      // Likewise, if the incoming PHI argument is equivalent to this
-      // PHI definition, it provides no new info.  Accumulate these ranges
-      // in case all arguments are equivalences.
-      if (src.query ()->query_relation (e, arg, phi_def, false) == EQ_EXPR)
-	{
-	  single_arg = arg;
-	  equiv_range.union_(arg_range);
-	  continue;
-	}
-
       if (!arg_range.undefined_p ())
 	{
 	  // Register potential dependencies for stale value tracking.
-	  r.union_ (arg_range);
+	  // Likewise, if the incoming PHI argument is equivalent to this
+	  // PHI definition, it provides no new info.  Accumulate these ranges
+	  // in case all arguments are equivalences.
+	  if (src.query ()->query_relation (e, arg, phi_def, false) == EQ_EXPR)
+	    equiv_range.union_(arg_range);
+	  else
+	    r.union_ (arg_range);
+
 	  if (gimple_range_ssa_p (arg) && src.gori ())
 	    src.gori ()->register_dependency (phi_def, arg);
 
@@ -829,7 +826,7 @@ fold_using_range::range_of_phi (irange &r, gphi *phi, fur_source &src)
 
     // If all arguments were equivalences, use the equivalence ranges as no
     // arguments were processed.
-    if (!seen_arg)
+    if (r.undefined_p () && !equiv_range.undefined_p ())
       r = equiv_range;
 
     // If the PHI boils down to a single effective argument, look at it.
diff --git a/gcc/testsuite/gcc.dg/pr103440.c b/gcc/testsuite/gcc.dg/pr103440.c
new file mode 100644
index 00000000000..b97f45cd3ed
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr103440.c
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+/* { dg-options "-Os" } */
+/* { dg-timeout 10 } */
+
+int a, b, c, d, e;
+int main() {
+  int f = 2, g = 1, h = -3;
+L1:
+  c = b ^ 1;
+  if (!f)
+    goto L3;
+  if (d)
+    g = e;
+  f = h;
+  if (!c)
+    goto L1;
+L2:
+  if (g)
+    a = 0;
+L3:
+  if (d == g)
+    goto L2;
+  return 0;
+}