diff mbox series

[15/21] middle-end: [RFC] conditionally support forcing final edge for debugging

Message ID ZUiYpncaG9ka5vKl@arm.com
State Unresolved
Headers
Series None |

Checks

Context Check Description
snail/gcc-patch-check warning Git am fail log

Commit Message

Tamar Christina Nov. 6, 2023, 7:41 a.m. UTC 
  Hi All,

What do people think about having the ability to force only the latch connected
exit as the exit as a param? I.e. what's in the patch but as a param.

I found this useful when debugging large example failures as it tells me where
I should be looking.  No hard requirement but just figured I'd ask if we should.

Thanks,
Tamar

gcc/ChangeLog:

	* tree-vect-loop.cc (vec_init_loop_exit_info): Allow forcing of exit.

--- inline copy of patch -- 
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 27ab6abfa854f14f8a4cf3d9fcb1ac1c203a4198..d6b35372623e94e02965510ab557cb568c302ebe 100644




--
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 27ab6abfa854f14f8a4cf3d9fcb1ac1c203a4198..d6b35372623e94e02965510ab557cb568c302ebe 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -964,6 +964,7 @@ vec_init_loop_exit_info (class loop *loop)
   if (exits.length () == 1)
     return exits[0];
 
+#if 0
   /* If we have multiple exits we only support counting IV at the moment.  Analyze
      all exits and return one */
   class tree_niter_desc niter_desc;
@@ -982,6 +983,16 @@ vec_init_loop_exit_info (class loop *loop)
     }
 
   return candidate;
+#else
+  basic_block bb = ip_normal_pos (loop);
+  if (!bb)
+    return NULL;
+
+  edge exit = EDGE_SUCC (bb, 0);
+  if (exit->dest == loop->latch)
+    return EDGE_SUCC (bb, 1);
+  return exit;
+#endif
 }
 
 /* Function bb_in_loop_p

Comments

Richard Sandiford Dec. 9, 2023, 10:38 a.m. UTC | #1 
Tamar Christina <tamar.christina@arm.com> writes:
> Hi All,
>
> What do people think about having the ability to force only the latch connected
> exit as the exit as a param? I.e. what's in the patch but as a param.
>
> I found this useful when debugging large example failures as it tells me where
> I should be looking.  No hard requirement but just figured I'd ask if we should.

If it's useful for that, then perhaps it would be worth making it a
DEBUG_COUNTER instead of a --param, for easy bisection.

Thanks,
Richard

>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> 	* tree-vect-loop.cc (vec_init_loop_exit_info): Allow forcing of exit.
>
> --- inline copy of patch -- 
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 27ab6abfa854f14f8a4cf3d9fcb1ac1c203a4198..d6b35372623e94e02965510ab557cb568c302ebe 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -964,6 +964,7 @@ vec_init_loop_exit_info (class loop *loop)
>    if (exits.length () == 1)
>      return exits[0];
>  
> +#if 0
>    /* If we have multiple exits we only support counting IV at the moment.  Analyze
>       all exits and return one */
>    class tree_niter_desc niter_desc;
> @@ -982,6 +983,16 @@ vec_init_loop_exit_info (class loop *loop)
>      }
>  
>    return candidate;
> +#else
> +  basic_block bb = ip_normal_pos (loop);
> +  if (!bb)
> +    return NULL;
> +
> +  edge exit = EDGE_SUCC (bb, 0);
> +  if (exit->dest == loop->latch)
> +    return EDGE_SUCC (bb, 1);
> +  return exit;
> +#endif
>  }
>  
>  /* Function bb_in_loop_p
Richard Biener Dec. 11, 2023, 7:38 a.m. UTC | #2 
On Sat, 9 Dec 2023, Richard Sandiford wrote:

> Tamar Christina <tamar.christina@arm.com> writes:
> > Hi All,
> >
> > What do people think about having the ability to force only the latch connected
> > exit as the exit as a param? I.e. what's in the patch but as a param.
> >
> > I found this useful when debugging large example failures as it tells me where
> > I should be looking.  No hard requirement but just figured I'd ask if we should.
> 
> If it's useful for that, then perhaps it would be worth making it a
> DEBUG_COUNTER instead of a --param, for easy bisection.

Or even better, make a debug counter that would skip the IV edge and
choose the "next".

Richard.

> Thanks,
> Richard
> 
> >
> > Thanks,
> > Tamar
> >
> > gcc/ChangeLog:
> >
> > 	* tree-vect-loop.cc (vec_init_loop_exit_info): Allow forcing of exit.
> >
> > --- inline copy of patch -- 
> > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> > index 27ab6abfa854f14f8a4cf3d9fcb1ac1c203a4198..d6b35372623e94e02965510ab557cb568c302ebe 100644
> > --- a/gcc/tree-vect-loop.cc
> > +++ b/gcc/tree-vect-loop.cc
> > @@ -964,6 +964,7 @@ vec_init_loop_exit_info (class loop *loop)
> >    if (exits.length () == 1)
> >      return exits[0];
> >  
> > +#if 0
> >    /* If we have multiple exits we only support counting IV at the moment.  Analyze
> >       all exits and return one */
> >    class tree_niter_desc niter_desc;
> > @@ -982,6 +983,16 @@ vec_init_loop_exit_info (class loop *loop)
> >      }
> >  
> >    return candidate;
> > +#else
> > +  basic_block bb = ip_normal_pos (loop);
> > +  if (!bb)
> > +    return NULL;
> > +
> > +  edge exit = EDGE_SUCC (bb, 0);
> > +  if (exit->dest == loop->latch)
> > +    return EDGE_SUCC (bb, 1);
> > +  return exit;
> > +#endif
> >  }
> >  
> >  /* Function bb_in_loop_p
>
Tamar Christina Dec. 11, 2023, 8:49 a.m. UTC | #3 
> -----Original Message-----
> From: Richard Biener <rguenther@suse.de>
> Sent: Monday, December 11, 2023 7:38 AM
> To: Richard Sandiford <Richard.Sandiford@arm.com>
> Cc: Tamar Christina <Tamar.Christina@arm.com>; gcc-patches@gcc.gnu.org; nd
> <nd@arm.com>; jlaw@ventanamicro.com
> Subject: Re: [PATCH 15/21]middle-end: [RFC] conditionally support forcing final
> edge for debugging
> 
> On Sat, 9 Dec 2023, Richard Sandiford wrote:
> 
> > Tamar Christina <tamar.christina@arm.com> writes:
> > > Hi All,
> > >
> > > What do people think about having the ability to force only the latch connected
> > > exit as the exit as a param? I.e. what's in the patch but as a param.
> > >
> > > I found this useful when debugging large example failures as it tells me where
> > > I should be looking.  No hard requirement but just figured I'd ask if we should.
> >
> > If it's useful for that, then perhaps it would be worth making it a
> > DEBUG_COUNTER instead of a --param, for easy bisection.
> 
> Or even better, make a debug counter that would skip the IV edge and
> choose the "next".
> 

Ah, I'd never heard of debug counters. They look very useful!

Did you mean everytime the counter is reached it picks the n-th successor?

So If the counter is hit twice it picks the 3rd exit?

Thanks,
Tamar
Richard Biener Dec. 11, 2023, 9 a.m. UTC | #4 
On Mon, 11 Dec 2023, Tamar Christina wrote:

> > -----Original Message-----
> > From: Richard Biener <rguenther@suse.de>
> > Sent: Monday, December 11, 2023 7:38 AM
> > To: Richard Sandiford <Richard.Sandiford@arm.com>
> > Cc: Tamar Christina <Tamar.Christina@arm.com>; gcc-patches@gcc.gnu.org; nd
> > <nd@arm.com>; jlaw@ventanamicro.com
> > Subject: Re: [PATCH 15/21]middle-end: [RFC] conditionally support forcing final
> > edge for debugging
> > 
> > On Sat, 9 Dec 2023, Richard Sandiford wrote:
> > 
> > > Tamar Christina <tamar.christina@arm.com> writes:
> > > > Hi All,
> > > >
> > > > What do people think about having the ability to force only the latch connected
> > > > exit as the exit as a param? I.e. what's in the patch but as a param.
> > > >
> > > > I found this useful when debugging large example failures as it tells me where
> > > > I should be looking.  No hard requirement but just figured I'd ask if we should.
> > >
> > > If it's useful for that, then perhaps it would be worth making it a
> > > DEBUG_COUNTER instead of a --param, for easy bisection.
> > 
> > Or even better, make a debug counter that would skip the IV edge and
> > choose the "next".
> > 
> 
> Ah, I'd never heard of debug counters. They look very useful!
> 
> Did you mean everytime the counter is reached it picks the n-th successor?
> 
> So If the counter is hit twice it picks the 3rd exit?

  if (!dbg_cnt (...))
    do not take this exit, try next

which means it might even fail to find an exit.


> Thanks,
> Tamar
>
diff mbox series

Patch

--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -964,6 +964,7 @@  vec_init_loop_exit_info (class loop *loop)
   if (exits.length () == 1)
     return exits[0];
 
+#if 0
   /* If we have multiple exits we only support counting IV at the moment.  Analyze
      all exits and return one */
   class tree_niter_desc niter_desc;
@@ -982,6 +983,16 @@  vec_init_loop_exit_info (class loop *loop)
     }
 
   return candidate;
+#else
+  basic_block bb = ip_normal_pos (loop);
+  if (!bb)
+    return NULL;
+
+  edge exit = EDGE_SUCC (bb, 0);
+  if (exit->dest == loop->latch)
+    return EDGE_SUCC (bb, 1);
+  return exit;
+#endif
 }
 
 /* Function bb_in_loop_p