[Bug tree-optimization] Fix for PR71994

[kugan]

Hi,

For testcase in pr71994, type of bb conditional result and the type of 
the PHI stmt are different (as om.0_1 is int and the first PHI argument 
is _bool; PHI stmt uses a constant zero that comes from edge 2). 
Therefore when we optimize final range test stmt, we end up setting 
integer 1 for other PHI argument. This results in ICE.

  <bb 2>:
  om.0_1 = om;
  _2 = om.0_1 >= 0;
  int _3 = (int) _2;
  if (om.0_1 != 0)
    goto <bb 3>;
  else
    goto <bb 4>;

  <bb 3>:
  int _4 = om.0_1 & _3;
  _Bool _12 = _4 != 0;
  <bb 4>:

  # _Bool _13 = PHI <0(2), _12(3)>


IMHO, the fix should be that, we should check the type before replacing 
the value (punt otherwise). Attached patch does that. Bootstrapped and 
regression tested on x86_64-linux-gnu with no new regressions. Is this 
OK for trunk?

Thanks,
Kugan

gcc/testsuite/ChangeLog:

2016-07-26  Kugan Vivekanandarajah  <kug...@linaro.org>

        * gcc.dg/torture/pr71994.c: New test.

gcc/ChangeLog:

2016-07-26  Kugan Vivekanandarajah  <kug...@linaro.org>

	* tree-ssa-reassoc.c (maybe_optimize_range_tests): Check type 
compatibility.

diff --git a/gcc/testsuite/gcc.dg/torture/pr71994.c 
b/gcc/testsuite/gcc.dg/torture/pr71994.c
index e69de29..8f5e92c 100644
--- a/gcc/testsuite/gcc.dg/torture/pr71994.c
+++ b/gcc/testsuite/gcc.dg/torture/pr71994.c
@@ -0,0 +1,14 @@
+/* PR tree-optimization/71994 */
+/* { dg-do compile } */
+int om, h6;
+
+void eo (void)
+{
+  const int tl = 1;
+  int ln;
+
+  h6 = (om + tl) > 0;
+  ln = om && (om & h6);
+  h6 = om;
+  om = ln < h6;
+}
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index 18cf978..91d7f06 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -3635,8 +3635,15 @@ maybe_optimize_range_tests (gimple *stmt)
                {
                  gcc_assert (bb == last_bb);
                  new_op = ops[bbinfo[idx].first_idx++]->op;
+                 if (!types_compatible_p (TREE_TYPE (new_op),
+                                          TREE_TYPE (bbinfo[idx].op))
+                     && TREE_CODE (new_op) == INTEGER_CST)
+                   new_op = fold_convert (TREE_TYPE (bbinfo[idx].op),
+                                          new_op);
                }
-             if (bbinfo[idx].op != new_op)
+             if (bbinfo[idx].op != new_op
+                 && types_compatible_p (TREE_TYPE (new_op),
+                                        TREE_TYPE (bbinfo[idx].op)))
                {
                  imm_use_iterator iter;
                  use_operand_p use_p;