Remove special checks for equivalences of the form: X .relop. Y.

It turns out these "equivalences" really only register overflow checks.  They notice:

unsigned_sum = unsigned_a + 1
if (unsigned_sum > unsigned_a)

and register that unsigned_a < MAXINT.

Instead of special checking this in the comparison and trap code, set gori_computable=false
in the overflow checking code.

2 files changed, 9 insertions, 6 deletions

diff --git a/gcc/gimple-ssa-evrp-analyze.c b/gcc/gimple-ssa-evrp-analyze.c
index d214418..0f14713 100644
--- a/gcc/gimple-ssa-evrp-analyze.c
+++ b/gcc/gimple-ssa-evrp-analyze.c
@@ -204,14 +204,8 @@ vr_gori_comparison::compare (tree name, edge e, vr_values *vr)
     {
       gcond *gc = as_a<gcond *> (stmt);
       tree lhs = gimple_cond_lhs (gc);
-      tree rhs = gimple_cond_rhs (gc);
       if (TREE_CODE (lhs) == SSA_NAME)
 	{
-	  // Comparison between two SSA_NAMEs are equivalences which the
-	  // ranger will handle.
-	  if (TREE_CODE (rhs) == SSA_NAME)
-	    return;
-
 	  // Ignore problematic casts for which evrp lies and ignores
 	  // the upper bits.
 	  //
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 2a9e434..1270d19 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -1863,6 +1863,15 @@ register_edge_assert_for_2 (tree name, edge e,
     {
       enum tree_code new_code = ((comp_code == GT_EXPR || comp_code == GE_EXPR)
 				 ? GT_EXPR : LE_EXPR);
+
+      // When noticing an overflow check:
+      //
+      //   unsigned_sum = unsigned_a + 1
+      //   if (unsigned_sum > unsigned_a)
+      //
+      // ...evrp registers that unsigned_a < MAXINT.
+      // This is technically an equivalence, so keep gori from checking this.
+      gori_computable set_gori_computable (false);
       add_assert_info (asserts, name, name, new_code, x);
     }
   add_assert_info (asserts, name, name, comp_code, val);