diff mbox

Fix cond updating in tree-ssa-dom (PR tree-optimization/77454)

Message ID 20160913074626.GB7282@tucnak.redhat.com
State New
Headers show

Commit Message

Jakub Jelinek Sept. 13, 2016, 7:46 a.m. UTC 
Hi!

The following testcase ICEs because SSA_NAME IMM links are broken.
I've tracked it to DOM's optimize_stmt, a GIMPLE_COND in there is
changed, marked as modified, then in optimize_stmt
  if (gimple_modified_p (stmt) || modified_p)
    {
      tree val = NULL;

      update_stmt_if_modified (stmt);
and a few lines later changed again:
              if (gimple_code (stmt) == GIMPLE_COND)
                {
                  if (integer_zerop (val))
                    gimple_cond_make_false (as_a <gcond *> (stmt));
                  else if (integer_onep (val))
                    gimple_cond_make_true (as_a <gcond *> (stmt));
without update_stmt.  As this is a function which update_stmt_if_modified
a few lines before, I think it is fine to update_stmt it immediately.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-09-13  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/77454
	* tree-ssa-dom.c (optimize_stmt): Call update_stmt after changing
	GIMPLE_COND.  Formatting fix.

	* gcc.dg/pr77454.c: New test.


	Jakub

Comments

Richard Biener Sept. 13, 2016, 1:21 p.m. UTC | #1 
On Tue, Sep 13, 2016 at 9:46 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> The following testcase ICEs because SSA_NAME IMM links are broken.
> I've tracked it to DOM's optimize_stmt, a GIMPLE_COND in there is
> changed, marked as modified, then in optimize_stmt
>   if (gimple_modified_p (stmt) || modified_p)
>     {
>       tree val = NULL;
>
>       update_stmt_if_modified (stmt);
> and a few lines later changed again:
>               if (gimple_code (stmt) == GIMPLE_COND)
>                 {
>                   if (integer_zerop (val))
>                     gimple_cond_make_false (as_a <gcond *> (stmt));
>                   else if (integer_onep (val))
>                     gimple_cond_make_true (as_a <gcond *> (stmt));
> without update_stmt.  As this is a function which update_stmt_if_modified
> a few lines before, I think it is fine to update_stmt it immediately.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok if it doesn't do the update twice this way (we do it the "fancy way" to
only update stmts we modified and do it only once).

Richard.

> 2016-09-13  Jakub Jelinek  <jakub@redhat.com>
>
>         PR tree-optimization/77454
>         * tree-ssa-dom.c (optimize_stmt): Call update_stmt after changing
>         GIMPLE_COND.  Formatting fix.
>
>         * gcc.dg/pr77454.c: New test.
>
> --- gcc/tree-ssa-dom.c.jj       2016-07-22 15:55:30.000000000 +0200
> +++ gcc/tree-ssa-dom.c  2016-09-09 12:29:28.006188533 +0200
> @@ -1927,8 +1927,9 @@ optimize_stmt (basic_block bb, gimple_st
>
>        if (gimple_code (stmt) == GIMPLE_COND)
>          val = fold_binary_loc (gimple_location (stmt),
> -                          gimple_cond_code (stmt), boolean_type_node,
> -                           gimple_cond_lhs (stmt),  gimple_cond_rhs (stmt));
> +                              gimple_cond_code (stmt), boolean_type_node,
> +                              gimple_cond_lhs (stmt),
> +                              gimple_cond_rhs (stmt));
>        else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
>         val = gimple_switch_index (swtch_stmt);
>
> @@ -1946,6 +1947,8 @@ optimize_stmt (basic_block bb, gimple_st
>                     gimple_cond_make_true (as_a <gcond *> (stmt));
>                   else
>                     gcc_unreachable ();
> +
> +                 update_stmt (stmt);
>                 }
>
>               /* Further simplifications may be possible.  */
> --- gcc/testsuite/gcc.dg/pr77454.c.jj   2016-09-09 12:34:47.540537483 +0200
> +++ gcc/testsuite/gcc.dg/pr77454.c      2016-09-09 12:32:47.000000000 +0200
> @@ -0,0 +1,28 @@
> +/* PR tree-optimization/77454 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +void
> +foo (unsigned char x, char y)
> +{
> +  while (x != 0)
> +    {
> +      unsigned char *a = &x;
> +      int b;
> +
> +      if (y != 0)
> +       a = (unsigned char *) &y;
> +      else if (y + 1 != 0)
> +       a = (unsigned char *) &y;
> +      for (x = 0; x < 1; ++x)
> +       b = 0;
> +      for (y = 0; y < 3; ++y)
> +       {
> +         y = !!y;
> +         if (y != 0)
> +           x = y;
> +       }
> +      if ((b != 0 ? -1 : *a) < (y = b))
> +       b = 1;
> +    }
> +}
>
>         Jakub
Jakub Jelinek Sept. 13, 2016, 1:32 p.m. UTC | #2 
On Tue, Sep 13, 2016 at 03:21:47PM +0200, Richard Biener wrote:
> > The following testcase ICEs because SSA_NAME IMM links are broken.
> > I've tracked it to DOM's optimize_stmt, a GIMPLE_COND in there is
> > changed, marked as modified, then in optimize_stmt
> >   if (gimple_modified_p (stmt) || modified_p)
> >     {
> >       tree val = NULL;
> >
> >       update_stmt_if_modified (stmt);
> > and a few lines later changed again:
> >               if (gimple_code (stmt) == GIMPLE_COND)
> >                 {
> >                   if (integer_zerop (val))
> >                     gimple_cond_make_false (as_a <gcond *> (stmt));
> >                   else if (integer_onep (val))
> >                     gimple_cond_make_true (as_a <gcond *> (stmt));
> > without update_stmt.  As this is a function which update_stmt_if_modified
> > a few lines before, I think it is fine to update_stmt it immediately.
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> Ok if it doesn't do the update twice this way (we do it the "fancy way" to
> only update stmts we modified and do it only once).

It does update it twice this way, the
       update_stmt_if_modified (stmt);
above is done first and then the newly added update_stmt again.

There is
      if (gimple_code (stmt) == GIMPLE_COND)
        val = fold_binary_loc (gimple_location (stmt),
                           gimple_cond_code (stmt), boolean_type_node,
                           gimple_cond_lhs (stmt),  gimple_cond_rhs (stmt));
      else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
        val = gimple_switch_index (swtch_stmt);

      if (val && TREE_CODE (val) == INTEGER_CST)
        {
          retval = find_taken_edge (bb, val);
and gimple_cond_make_{false,true} in between.  If none of these care about
the stmt being updated (gimple_cond_make_{false,true} and
gimple_switch_index is surely ok, dyn_cast too, not 100% sure about
fold_binary (if it can't use match.pd, though on the other side it is not
passed the stmt, but only its arguments), or find_taken_edge (most likely
ok)), then I could perhaps change the patch to do gimple_set_modified (stmt,
true); where I've added the update_stmt, and move the
update_stmt_if_modified call after the if (val && TREE_CODE (val) ==
INTEGER_CST) { ... } stmt.

	Jakub
Richard Biener Sept. 13, 2016, 2:02 p.m. UTC | #3 
On September 13, 2016 3:32:33 PM GMT+02:00, Jakub Jelinek <jakub@redhat.com> wrote:
>On Tue, Sep 13, 2016 at 03:21:47PM +0200, Richard Biener wrote:
>> > The following testcase ICEs because SSA_NAME IMM links are broken.
>> > I've tracked it to DOM's optimize_stmt, a GIMPLE_COND in there is
>> > changed, marked as modified, then in optimize_stmt
>> >   if (gimple_modified_p (stmt) || modified_p)
>> >     {
>> >       tree val = NULL;
>> >
>> >       update_stmt_if_modified (stmt);
>> > and a few lines later changed again:
>> >               if (gimple_code (stmt) == GIMPLE_COND)
>> >                 {
>> >                   if (integer_zerop (val))
>> >                     gimple_cond_make_false (as_a <gcond *> (stmt));
>> >                   else if (integer_onep (val))
>> >                     gimple_cond_make_true (as_a <gcond *> (stmt));
>> > without update_stmt.  As this is a function which
>update_stmt_if_modified
>> > a few lines before, I think it is fine to update_stmt it
>immediately.
>> >
>> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for
>trunk?
>> 
>> Ok if it doesn't do the update twice this way (we do it the "fancy
>way" to
>> only update stmts we modified and do it only once).
>
>It does update it twice this way, the
>       update_stmt_if_modified (stmt);
>above is done first and then the newly added update_stmt again.
>
>There is
>      if (gimple_code (stmt) == GIMPLE_COND)
>        val = fold_binary_loc (gimple_location (stmt),
>                           gimple_cond_code (stmt), boolean_type_node,
>                      gimple_cond_lhs (stmt),  gimple_cond_rhs (stmt));
>      else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
>        val = gimple_switch_index (swtch_stmt);
>
>      if (val && TREE_CODE (val) == INTEGER_CST)
>        {
>          retval = find_taken_edge (bb, val);
>and gimple_cond_make_{false,true} in between.  If none of these care
>about
>the stmt being updated (gimple_cond_make_{false,true} and
>gimple_switch_index is surely ok, dyn_cast too, not 100% sure about
>fold_binary (if it can't use match.pd, though on the other side it is
>not
>passed the stmt, but only its arguments), or find_taken_edge (most
>likely
>ok)), then I could perhaps change the patch to do gimple_set_modified
>(stmt,
>true); where I've added the update_stmt, and move the
>update_stmt_if_modified call after the if (val && TREE_CODE (val) ==
>INTEGER_CST) { ... } stmt.

Yes please, this should be safe.  All of the above do not look at immediate uses but at most use-def links.

Richard.

>	Jakub
diff mbox

Patch

--- gcc/tree-ssa-dom.c.jj	2016-07-22 15:55:30.000000000 +0200
+++ gcc/tree-ssa-dom.c	2016-09-09 12:29:28.006188533 +0200
@@ -1927,8 +1927,9 @@  optimize_stmt (basic_block bb, gimple_st
 
       if (gimple_code (stmt) == GIMPLE_COND)
         val = fold_binary_loc (gimple_location (stmt),
-			   gimple_cond_code (stmt), boolean_type_node,
-                           gimple_cond_lhs (stmt),  gimple_cond_rhs (stmt));
+			       gimple_cond_code (stmt), boolean_type_node,
+			       gimple_cond_lhs (stmt),
+			       gimple_cond_rhs (stmt));
       else if (gswitch *swtch_stmt = dyn_cast <gswitch *> (stmt))
 	val = gimple_switch_index (swtch_stmt);
 
@@ -1946,6 +1947,8 @@  optimize_stmt (basic_block bb, gimple_st
 		    gimple_cond_make_true (as_a <gcond *> (stmt));
 		  else
 		    gcc_unreachable ();
+
+		  update_stmt (stmt);
 		}
 
 	      /* Further simplifications may be possible.  */
--- gcc/testsuite/gcc.dg/pr77454.c.jj	2016-09-09 12:34:47.540537483 +0200
+++ gcc/testsuite/gcc.dg/pr77454.c	2016-09-09 12:32:47.000000000 +0200
@@ -0,0 +1,28 @@ 
+/* PR tree-optimization/77454 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void
+foo (unsigned char x, char y)
+{
+  while (x != 0)
+    {
+      unsigned char *a = &x;
+      int b;
+
+      if (y != 0)
+	a = (unsigned char *) &y;
+      else if (y + 1 != 0)
+	a = (unsigned char *) &y;
+      for (x = 0; x < 1; ++x)
+	b = 0;
+      for (y = 0; y < 3; ++y)
+	{
+	  y = !!y;
+	  if (y != 0)
+	    x = y;
+	}
+      if ((b != 0 ? -1 : *a) < (y = b))
+	b = 1;
+    }
+}