Re: [PATCH, PR 63551] Use proper type in evaluate_conditions_for_known_args

[Martin Jambor]

Hi,

On Fri, Nov 21, 2014 at 09:18:03PM +0100, Richard Biener wrote:
> On November 21, 2014 9:07:50 PM CET, Martin Jambor <mjam...@suse.cz> wrote:
> >the testcase of PR 63551 passes a union between a signed and an
> >unsigned integer between two functions as a parameter.  The caller
> >initializes to an unsigned integer with the highest order bit set, the
> >callee loads the data through the signed field and compares with zero.
> >evaluate_conditions_for_known_args then wrongly evaluated the
> >condition in these circumstances, which later on lead to insertion of
> >builtin_unreachable and miscompilation.
> >
> >Fixed by fold_converting the known value first.  I use the type of the
> >value in the condition which should do exactly the right thing because
> >the value is taken from the corresponding gimple_cond statement in
> >which types must match.
> >
> >Bootstrapped and tested on x86_64-linux.  OK for trunk?
> 
> I think you want to use fold_unary (VIEW_CONVERT,...) Here if you consider 
> the case with
> Int and float.  And "fail" if that returns NULL or not a constant.
> 

You are of course right.  The following does exactly that.
Bootstrapped and tested on x86_64-linux on trunk and the 4.9 branch.
OK for both?

Thanks,

Martin


2014-11-21  Martin Jambor  <mjam...@suse.cz>

        PR ipa/63551
        * ipa-inline-analysis.c (evaluate_conditions_for_known_args): Convert
        value of the argument to the type of the value in the condition.

testsuite/
        * gcc.dg/ipa/pr63551.c: New test.


Index: src/gcc/ipa-inline-analysis.c
===================================================================
--- src.orig/gcc/ipa-inline-analysis.c
+++ src/gcc/ipa-inline-analysis.c
@@ -880,7 +880,10 @@ evaluate_conditions_for_known_args (stru
        }
       if (c->code == IS_NOT_CONSTANT || c->code == CHANGED)
        continue;
-      res = fold_binary_to_constant (c->code, boolean_type_node, val, c->val);
+      val = fold_unary (VIEW_CONVERT_EXPR, TREE_TYPE (c->val), val);
+      res = val
+       ? fold_binary_to_constant (c->code, boolean_type_node, val, c->val)
+       : NULL;
       if (res && integer_zerop (res))
        continue;
       clause |= 1 << (i + predicate_first_dynamic_condition);
Index: src/gcc/testsuite/gcc.dg/ipa/pr63551.c
===================================================================
--- /dev/null
+++ src/gcc/testsuite/gcc.dg/ipa/pr63551.c
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+/* { dg-options "-Os" } */
+
+union U
+{
+  unsigned int f0;
+  int f1;
+};
+
+int a, d;
+
+void
+fn1 (union U p)
+{
+  if (p.f1 <= 0)
+    if (a)
+      d = 0;
+}
+
+void
+fn2 ()
+{
+  d = 0;
+  union U b = { 4294967286 };
+  fn1 (b);
+}
+
+int
+main ()
+{
+  fn2 ();
+  return 0;
+}