diff mbox

[PR70920] transform (intptr_t) x eq/ne CST to x eq/ne (typeof x) cst

Message ID CAAgBjMmz2tWj4WL2sKtKJtZfY2OjN+xpRGf7QNOFyhTXkw6h1g@mail.gmail.com
State Superseded
Headers show

Commit Message

Prathamesh Kulkarni July 29, 2016, 2:32 p.m. UTC 
On 29 July 2016 at 12:42, Richard Biener <rguenther@suse.de> wrote:
> On Fri, 29 Jul 2016, Prathamesh Kulkarni wrote:

>

>> On 28 July 2016 at 19:18, Richard Biener <rguenther@suse.de> wrote:

>> > On Thu, 28 Jul 2016, Prathamesh Kulkarni wrote:

>> >

>> >> On 28 July 2016 at 15:58, Andreas Schwab <schwab@suse.de> wrote:

>> >> > On Mo, Jul 25 2016, Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> wrote:

>> >> >

>> >> >> diff --git a/gcc/testsuite/gcc.dg/pr70920-4.c b/gcc/testsuite/gcc.dg/pr70920-4.c

>> >> >> new file mode 100644

>> >> >> index 0000000..dedb895

>> >> >> --- /dev/null

>> >> >> +++ b/gcc/testsuite/gcc.dg/pr70920-4.c

>> >> >> @@ -0,0 +1,21 @@

>> >> >> +/* { dg-do compile } */

>> >> >> +/* { dg-options "-O2 -fdump-tree-ccp-details -Wno-int-to-pointer-cast" } */

>> >> >> +

>> >> >> +#include <stdint.h>

>> >> >> +

>> >> >> +void f1();

>> >> >> +void f2();

>> >> >> +

>> >> >> +void

>> >> >> +foo (int a)

>> >> >> +{

>> >> >> +  void *cst = 0;

>> >> >> +  if ((int *) a == cst)

>> >> >> +    {

>> >> >> +      f1 ();

>> >> >> +      if (a)

>> >> >> +     f2 ();

>> >> >> +    }

>> >> >> +}

>> >> >> +

>> >> >> +/* { dg-final { scan-tree-dump "gimple_simplified to if \\(_\[0-9\]* == 0\\)" "ccp1" } } */

>> >> >

>> >> > This fails on all ilp32 platforms.

>> >> Oops, sorry for the breakage.

>> >> With -m32, the pattern is applied during forwprop1 rather than ccp1.

>> >> I wonder though why ccp1 fails to fold the pattern with -m32 ?

>> >> Looking at the dumps:

>> >>

>> >> without -m32:

>> >> input to ccp1 pass:

>> >>   <bb 2>:

>> >>   cst_4 = 0B;

>> >>   _1 = (long int) a_5(D);

>> >>   _2 = (void *) _1;

>> >>   if (cst_4 == _2)

>> >>     goto <bb 3>;

>> >>   else

>> >>     goto <bb 5>;

>> >>

>> >> cc1 pass dump shows:

>> >> Substituting values and folding statements

>> >>

>> >> Folding statement: _1 = (long int) a_5(D);

>> >> Not folded

>> >> Folding statement: _2 = (void *) _1;

>> >> Not folded

>> >> Folding statement: if (cst_4 == _2)

>> >> which is likely CONSTANT

>> >> Applying pattern match.pd:2537, gimple-match.c:6530

>> >> gimple_simplified to if (_1 == 0)

>> >> Folded into: if (_1 == 0)

>> >>

>> >> with -m32:

>> >> input to ccp1 pass:

>> >>  <bb 2>:

>> >>   cst_3 = 0B;

>> >>   a.0_1 = (void *) a_4(D);

>> >>   if (cst_3 == a.0_1)

>> >>     goto <bb 3>;

>> >>   else

>> >>     goto <bb 5>;

>> >>

>> >> ccp1 pass dump shows:

>> >> Substituting values and folding statements

>> >>

>> >> Folding statement: a.0_1 = (void *) a_4(D);

>> >> Not folded

>> >> Folding statement: if (cst_3 == a.0_1)

>> >> which is likely CONSTANT

>> >> Folded into: if (a.0_1 == 0B)

>> >>

>> >> I am not able to understand why it doesn't fold it to

>> >> if (a_4(D) == 0) ?

>> >> forwprop1 folds a.0_1 == 0B to a_4(D) == 0.

>> >

>> > It's because CCP folds with follow-single-use edges but the

>> > match-and-simplify code uses a single callback to valueize and

>> > decide whether its valid to follow the SSA edge.  I did have some

>> > old patches trying to fix that but never followed up on those.

>> Thanks for the explanation.

>> >

>> >> I suppose the test-case would need to scan ccp1 for non-ilp targets

>> >> and forwprop1 for

>> >> ilp targets. How do update the test-case to reflect this ?

>> >

>> > It's simpler to verify that at some point (forwprop) we have the

>> > expected IL rather than testing for the match debug prints.

>> In forwprop dump,

>> For m32, we have if (a_4(D) == 0)

>> and without m32: if (_1 == 0)

>> So need to match either a default def or anonymous name

>> in the test-case, which I am having a bit of trouble writing regex for.

>> In the patch i simply chose to match "== 0\\)", not sure if that's a good idea.

>> Also how do I update the test-case so that it gets tested twice, once with -m32

>> and once without ?

>

> I don't think just matching == 0 is a good idea.  I suggest to

> restrict the testcase to lp64 targets and maybe add a ilp32 variant.

Hi,
I restricted the test-case to lp64 targets.
Is this OK to commit ?

Thanks,
Prathamesh
>

> Richard.

>

>> Thanks,

>> Prathamesh

>> >

>> > Richard.

>> >

>> >> Thanks,

>> >> Prathamesh

>> >> >

>> >> > Andreas.

>> >> >

>> >> > --

>> >> > Andreas Schwab, SUSE Labs, schwab@suse.de

>> >> > GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7

>> >> > "And now for something completely different."

>> >>

>> >>

>> >

>> > --

>> > Richard Biener <rguenther@suse.de>

>> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)

>>

>

> --

> Richard Biener <rguenther@suse.de>

> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
2016-07-29  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

testsuite/
	gcc.dg/pr70920-4.c: Restrict to lp64 targets and make scan-tree-dump
	to scan forwprop1 dump pass.
diff mbox

Patch

diff --git a/gcc/testsuite/gcc.dg/pr70920-4.c b/gcc/testsuite/gcc.dg/pr70920-4.c
index dedb895..ab2748b 100644
--- a/gcc/testsuite/gcc.dg/pr70920-4.c
+++ b/gcc/testsuite/gcc.dg/pr70920-4.c
@@ -1,5 +1,6 @@ 
+/* { dg-require-effective-target lp64 } */
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-ccp-details -Wno-int-to-pointer-cast" } */
+/* { dg-options "-O2 -fdump-tree-forwprop-details -Wno-int-to-pointer-cast" } */
 
 #include <stdint.h>
 
@@ -18,4 +19,4 @@  foo (int a)
     }
 }
 
-/* { dg-final { scan-tree-dump "gimple_simplified to if \\(_\[0-9\]* == 0\\)" "ccp1" } } */
+/* { dg-final { scan-tree-dump "if \\(_\[0-9\]* == 0\\)" "forwprop1" } } */