[PATCH] Fix up reassoc range test optimization (PR tree-optimization/59388)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

range->exp can in some cases be equal to op, as in the following testcase:
  <unnamed-unsigned:1> _2;
  int _3;
  _Bool _4;
  int a.0_5;
  _Bool _7;

  <bb 2>:
  _2 = b.f;
  _3 = (int) _2;
  _4 = _3 > 0;
  _7 = _2 | _4;
  a.0_5 = (int) _7;
  a = a.0_5;
  return a.0_5;

op here is _2 (and other range's op is _4), the two range tests have been
successfully merged and the code chose to use the first one to be the one
that is kept.  Normally the range test isn't a SSA_NAME itself, but say
comparison etc. and thus emitting the statements before the statement
is desirable, but in this case we can't emit the new statements before it,
as they use _2.  Fixed thusly, bootstrapped/regtested on x86_64-linux and
i686-linux, ok for trunk and 4.8 (for the latter the fix is tiny bit
different, therefore attached)?

2013-12-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/59388
	* tree-ssa-reassoc.c (update_range_test): If op == range->exp,
	gimplify tem after stmt rather than before it.

	* gcc.c-torture/execute/pr59388.c: New test.

--- gcc/tree-ssa-reassoc.c.jj	2013-11-23 15:21:23.000000000 +0100
+++ gcc/tree-ssa-reassoc.c	2013-12-06 17:27:01.908908702 +0100
@@ -2072,9 +2072,19 @@ update_range_test (struct range_entry *r
 
   tem = fold_convert_loc (loc, optype, tem);
   gsi = gsi_for_stmt (stmt);
-  tem = force_gimple_operand_gsi (&gsi, tem, true, NULL_TREE, true,
-				  GSI_SAME_STMT);
-  for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
+  /* In rare cases range->exp can be equal to lhs of stmt.
+     In that case we have to insert after the stmt rather then before
+     it.  */
+  if (op == range->exp)
+    tem = force_gimple_operand_gsi (&gsi, tem, true, NULL_TREE, false,
+				    GSI_CONTINUE_LINKING);
+  else
+    {
+      tem = force_gimple_operand_gsi (&gsi, tem, true, NULL_TREE, true,
+				      GSI_SAME_STMT);
+      gsi_prev (&gsi);
+    }
+  for (; !gsi_end_p (gsi); gsi_prev (&gsi))
     if (gimple_uid (gsi_stmt (gsi)))
       break;
     else
--- gcc/testsuite/gcc.c-torture/execute/pr59388.c.jj	2013-12-06 17:41:55.811244282 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr59388.c	2013-12-06 17:32:28.000000000 +0100
@@ -0,0 +1,11 @@
+/* PR tree-optimization/59388 */
+
+int a;
+struct S { unsigned int f:1; } b;
+
+int
+main ()
+{
+  a = (0 < b.f) | b.f;
+  return a;
+}

	Jakub

Attachment: gcc48-pr59388.patch
Description: Text document