[COMMITTED] PR tree-optimization/106621 - Check for undefined and varying first.

[Andrew MacLeod via Gcc-patches]

We treat POLY_INT_CSTs as VARYING, but the check in irange::set for them 
was occurring after we called irange::set_range.  This patch merely 
shuffles the orders of checks around such that we check for undefined, 
and then varying/polyints before the other cases.  Performance impact is 
negligible.

bootstraps on 86_64-pc-linux-gnu with no regressions. Compilation 
reproduced the PR and patch passes the test on a cross compiler for 
aarch64.  I have no access to bootstrap on aarch64. Hopefully the 
testcase works as provided :)

pushed.

Andrew

commit 265cdd067afd56293137ecb3057c5ba28a7c9480
Author: Andrew MacLeod <amacl...@redhat.com>
Date:   Mon Aug 15 10:16:23 2022 -0400

    Check for undefined and varying first.
    
    Rearrange order in irange:set to ensure all POLY_INTs map to varying.
    
            PR tree-optimization/106621
            gcc/
            * value-range.cc (irange::set): Check for POLY_INT_CST early.
    
            gcc/testsuite/
            * gcc.dg/pr106621.c

diff --git a/gcc/testsuite/gcc.dg/pr106621.c b/gcc/testsuite/gcc.dg/pr106621.c
new file mode 100644
index 00000000000..0465de4f14f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr106621.c
@@ -0,0 +1,30 @@
+/* { dg-do compile { target aarch64*-*-* } } */
+/* { dg-options "-mcpu=neoverse-v1 -O2 -fvect-cost-model=dynamic -fno-tree-scev-cprop" } */
+
+int m, n;
+
+void
+foo (unsigned int x, short int y)
+{
+  if (m)
+    for (;;)
+      {
+        ++m;
+        while (m < 1)
+          {
+            n += m + x;
+            ++m;
+          }
+      }
+
+  for (;;)
+    if (y)
+      {
+        ++x;
+        if (x)
+          for (y = 0; y < 75; y += 2)
+            {
+            }
+      }
+}
+
diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index a2273f540e8..d056f7356e1 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -716,25 +716,6 @@ irange::irange_set_anti_range (tree min, tree max)
 void
 irange::set (tree min, tree max, value_range_kind kind)
 {
-  if (kind != VR_UNDEFINED)
-    {
-      if (TREE_OVERFLOW_P (min))
-	min = drop_tree_overflow (min);
-      if (TREE_OVERFLOW_P (max))
-	max = drop_tree_overflow (max);
-    }
-
-  if (!legacy_mode_p ())
-    {
-      if (kind == VR_RANGE)
-	irange_set (min, max);
-      else
-	{
-	  gcc_checking_assert (kind == VR_ANTI_RANGE);
-	  irange_set_anti_range (min, max);
-	}
-      return;
-    }
   if (kind == VR_UNDEFINED)
     {
       irange::set_undefined ();
@@ -749,6 +730,22 @@ irange::set (tree min, tree max, value_range_kind kind)
       return;
     }
 
+  if (TREE_OVERFLOW_P (min))
+    min = drop_tree_overflow (min);
+  if (TREE_OVERFLOW_P (max))
+    max = drop_tree_overflow (max);
+
+  if (!legacy_mode_p ())
+    {
+      if (kind == VR_RANGE)
+	irange_set (min, max);
+      else
+	{
+	  gcc_checking_assert (kind == VR_ANTI_RANGE);
+	  irange_set_anti_range (min, max);
+	}
+      return;
+    }
   // Nothing to canonicalize for symbolic ranges.
   if (TREE_CODE (min) != INTEGER_CST
       || TREE_CODE (max) != INTEGER_CST)