diff mbox

Fix PR tree-optimization/71170

Message ID CAELXzTPsEH67qeYf77dLfQYpEFQ=pFA2n+eXQkcB5qCVRfSmnw@mail.gmail.com
State New
Headers show

Commit Message

Kugan Vivekanandarajah May 24, 2016, 8:46 a.m. UTC 
On 24 May 2016 at 18:36, Christophe Lyon <christophe.lyon@linaro.org> wrote:
> On 24 May 2016 at 05:13, Kugan Vivekanandarajah

> <kugan.vivekanandarajah@linaro.org> wrote:

>> On 23 May 2016 at 21:35, Richard Biener <richard.guenther@gmail.com> wrote:

>>> On Sat, May 21, 2016 at 8:08 AM, Kugan Vivekanandarajah

>>> <kugan.vivekanandarajah@linaro.org> wrote:

>>>> On 20 May 2016 at 21:07, Richard Biener <richard.guenther@gmail.com> wrote:

>>>>> On Fri, May 20, 2016 at 1:51 AM, Kugan Vivekanandarajah

>>>>> <kugan.vivekanandarajah@linaro.org> wrote:

>>>>>> Hi Richard,

>>>>>>

>>>>>>> I think it should have the same rank as op or op + 1 which is the current

>>>>>>> behavior.  Sth else doesn't work correctly here I think, like inserting the

>>>>>>> multiplication not near the definition of op.

>>>>>>>

>>>>>>> Well, the whole "clever insertion" logic is simply flawed.

>>>>>>

>>>>>> What I meant to say was that the simple logic we have now wouldn’t

>>>>>> work. "clever logic" is knowing where exactly where it is needed and

>>>>>> inserting there.  I think thats what  you are suggesting below in a

>>>>>> simple to implement way.

>>>>>>

>>>>>>> I'd say that ideally we would delay inserting the multiplication to

>>>>>>> rewrite_expr_tree time.  For example by adding a ops->stmt_to_insert

>>>>>>> member.

>>>>>>>

>>>>>>

>>>>>> Here is an implementation based on above. Bootstrap on x86-linux-gnu

>>>>>> is OK. regression testing is ongoing.

>>>>>

>>>>> I like it.  Please push the insertion code to a helper as I think you need

>>>>> to post-pone setting the stmts UID to that point.

>>>>>

>>>>> Ideally we'd make use of the same machinery in attempt_builtin_powi,

>>>>> removing the special-casing of powi_result.  (same as I said that ideally

>>>>> the plus->mult stuff would use the repeat-ops machinery...)

>>>>>

>>>>> I'm not 100% convinced the place you insert the stmt is correct but I

>>>>> haven't spent too much time to decipher reassoc in this area.

>>>>

>>>>

>>>> Hi Richard,

>>>>

>>>> Thanks. Here is a tested version of the patch. I did miss one place

>>>> which I fixed now (tranform_stmt_to_copy) I also created a function to

>>>> do the insertion.

>>>>

>>>>

>>>> Bootstrap and regression testing on x86_64-linux-gnu are fine. Is this

>>>> OK for trunk.

>>>

>>> @@ -3798,6 +3805,7 @@ rewrite_expr_tree (gimple *stmt, unsigned int opindex,

>>>        oe1 = ops[opindex];

>>>        oe2 = ops[opindex + 1];

>>>

>>> +

>>>        if (rhs1 != oe1->op || rhs2 != oe2->op)

>>>         {

>>>           gimple_stmt_iterator gsi = gsi_for_stmt (stmt);

>>>

>>> please remove this stray change.

>>>

>>> Ok with that change.

>>

>> Hi Richard,

>>

>> Thanks for the review. I also found another issue with this patch.

>> I.e. for the stmt_to_insert we will get gimple_bb of NULL which is not

>> expected in sort_by_operand_rank. This only showed up only while

>> building a version of glibc.

>>

>> Bootstrap and regression testing are ongoing.Is this OK for trunk if

>> passes regression and bootstrap.

>>

>

> I'm seeing build failures in glibc after you committed r236619.

> This new patch is fixing it, right?



Yes (same patch attached). Also Bootstrap and regression testing on
x86_64-linux-gnu didn’t have no new failures.

Is this OK for trunk?

Thanks,
Kugan

gcc/ChangeLog:

2016-05-24  Kugan Vivekanandarajah  <kuganv@linaro.org>

    * tree-ssa-reassoc.c (sort_by_operand_rank): Check fgimple_bb for NULL.


gcc/testsuite/ChangeLog:

2016-05-24  Kugan Vivekanandarajah  <kuganv@linaro.org>

    * gcc.dg/tree-ssa/reassoc-44.c: New test.
diff mbox

Patch

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/reassoc-44.c b/gcc/testsuite/gcc.dg/tree-ssa/reassoc-44.c
index e69de29..9b12212 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/reassoc-44.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/reassoc-44.c
@@ -0,0 +1,10 @@ 
+
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+unsigned int a;
+int b, c;
+void fn1 ()
+{
+  b = a + c + c;
+}
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index fb683ad..06f4d1b 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -525,7 +525,7 @@  sort_by_operand_rank (const void *pa, const void *pb)
 	  gimple *stmtb = SSA_NAME_DEF_STMT (oeb->op);
 	  basic_block bba = gimple_bb (stmta);
 	  basic_block bbb = gimple_bb (stmtb);
-	  if (bbb != bba)
+	  if (bba && bbb && bbb != bba)
 	    {
 	      if (bb_rank[bbb->index] != bb_rank[bba->index])
 		return bb_rank[bbb->index] - bb_rank[bba->index];