Message ID | patch-18254-tamar@arm.com |
---|---|
State | New |
Headers | show |
Series | middle-end: add two debug counters for early-break vectorization debugging | expand |
On Thu, 8 Feb 2024, Tamar Christina wrote: > Hi All, > > This adds two new debug counter to aid in debugging early break code. > > - vect_force_last_exit: when reached will always force the final loop exit. > - vect_skip_exit: when reached will skip selecting the current candidate exit > as the loop exit. > > The first counter essentially allows you to turn off the PEELED case and the > second counter to pick a different exit, which may mean you pick no exit at > all. > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > Ok for master? > > Thanks, > Tamar > > gcc/ChangeLog: > > * dbgcnt.def (vect_force_last_exit, vect_skip_exit): New. > * tree-vect-loop.cc (vec_init_loop_exit_info): Use them. > > --- inline copy of patch -- > diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def > index ed9f062eac2c28c52df76b39d4312dd9fde1c800..8f7bebf93fceabdf6ae86c2df591eae4848b8a5c 100644 > --- a/gcc/dbgcnt.def > +++ b/gcc/dbgcnt.def > @@ -213,5 +213,7 @@ DEBUG_COUNTER (stv_conversion) > DEBUG_COUNTER (tail_call) > DEBUG_COUNTER (tree_sra) > DEBUG_COUNTER (treepre_insert) > +DEBUG_COUNTER (vect_force_last_exit) > DEBUG_COUNTER (vect_loop) > +DEBUG_COUNTER (vect_skip_exit) > DEBUG_COUNTER (vect_slp) > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc > index eed2268e9bae7e7ad36d13da03e0b54eab26ef6f..854e9d78bc71721e6559a6bc5dff78c813603a78 100644 > --- a/gcc/tree-vect-loop.cc > +++ b/gcc/tree-vect-loop.cc > @@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see > #include "tree-eh.h" > #include "case-cfn-macros.h" > #include "langhooks.h" > +#include "dbgcnt.h" > > /* Loop Vectorization Pass. > > @@ -977,6 +978,20 @@ vec_init_loop_exit_info (class loop *loop) > if (exits.length () == 1) > return exits[0]; > > + /* Check to see if we've been asked to force the last exit. */ > + if (!dbg_cnt (vect_force_last_exit)) > + { > + 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; Err, that's quite odd. Why not just below do > + } > + > /* If we have multiple exits we only support counting IV at the moment. > Analyze all exits and return the last one we can analyze. */ > class tree_niter_desc niter_desc; > @@ -998,6 +1013,7 @@ vec_init_loop_exit_info (class loop *loop) > && exit->src == single_pred (loop->latch) > && (integer_nonzerop (may_be_zero) > || COMPARISON_CLASS_P (may_be_zero)))) > + && dbg_cnt (vect_skip_exit) && (dbg_cnt (vect_force_last_exit) || exit->src == single_pred (loop->latch)) (also computed above already)? It's also oddly named, it's more like vect_allow_peeled_exit or so. It's also seemingly redundant with vect_skip_exit, no? Note the counter gets incremented even if we'd not consider the exit because we have a later candidate already. I fear it's going to be quite random even with the debug counter. Can you see whether it really helps you? > && (!candidate > || dominated_by_p (CDI_DOMINATORS, exit->src, > candidate->src))) > > > > >
> -----Original Message----- > From: Richard Biener <rguenther@suse.de> > Sent: Thursday, February 8, 2024 2:16 PM > To: Tamar Christina <Tamar.Christina@arm.com> > Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; jlaw@ventanamicro.com > Subject: Re: [PATCH]middle-end: add two debug counters for early-break > vectorization debugging > > On Thu, 8 Feb 2024, Tamar Christina wrote: > > > Hi All, > > > > This adds two new debug counter to aid in debugging early break code. > > > > - vect_force_last_exit: when reached will always force the final loop exit. > > - vect_skip_exit: when reached will skip selecting the current candidate exit > > as the loop exit. > > > > The first counter essentially allows you to turn off the PEELED case and the > > second counter to pick a different exit, which may mean you pick no exit at > > all. > > > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > > > Ok for master? > > > > Thanks, > > Tamar > > > > gcc/ChangeLog: > > > > * dbgcnt.def (vect_force_last_exit, vect_skip_exit): New. > > * tree-vect-loop.cc (vec_init_loop_exit_info): Use them. > > > > --- inline copy of patch -- > > diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def > > index > ed9f062eac2c28c52df76b39d4312dd9fde1c800..8f7bebf93fceabdf6ae86c2df5 > 91eae4848b8a5c 100644 > > --- a/gcc/dbgcnt.def > > +++ b/gcc/dbgcnt.def > > @@ -213,5 +213,7 @@ DEBUG_COUNTER (stv_conversion) > > DEBUG_COUNTER (tail_call) > > DEBUG_COUNTER (tree_sra) > > DEBUG_COUNTER (treepre_insert) > > +DEBUG_COUNTER (vect_force_last_exit) > > DEBUG_COUNTER (vect_loop) > > +DEBUG_COUNTER (vect_skip_exit) > > DEBUG_COUNTER (vect_slp) > > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc > > index > eed2268e9bae7e7ad36d13da03e0b54eab26ef6f..854e9d78bc71721e6559a6bc > 5dff78c813603a78 100644 > > --- a/gcc/tree-vect-loop.cc > > +++ b/gcc/tree-vect-loop.cc > > @@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see > > #include "tree-eh.h" > > #include "case-cfn-macros.h" > > #include "langhooks.h" > > +#include "dbgcnt.h" > > > > /* Loop Vectorization Pass. > > > > @@ -977,6 +978,20 @@ vec_init_loop_exit_info (class loop *loop) > > if (exits.length () == 1) > > return exits[0]; > > > > + /* Check to see if we've been asked to force the last exit. */ > > + if (!dbg_cnt (vect_force_last_exit)) > > + { > > + 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; > > Err, that's quite odd. Why not just below do > > > + } > > + > > /* If we have multiple exits we only support counting IV at the moment. > > Analyze all exits and return the last one we can analyze. */ > > class tree_niter_desc niter_desc; > > @@ -998,6 +1013,7 @@ vec_init_loop_exit_info (class loop *loop) > > && exit->src == single_pred (loop->latch) > > && (integer_nonzerop (may_be_zero) > > || COMPARISON_CLASS_P (may_be_zero)))) > > + && dbg_cnt (vect_skip_exit) > > && (dbg_cnt (vect_force_last_exit) > || exit->src == single_pred (loop->latch)) > > (also computed above already)? It's also oddly named, it's more like > vect_allow_peeled_exit or so. Because this isn't deterministic. If a loop has n exits the above always forces you to pick the final one regardless of n, rather than just skip consideration of an exit. And in that case is there a point in analyzing all the exits just to throw away the information? Doing in inside the consideration check would only skip one exit unless I'm misunderstanding. > > It's also seemingly redundant with vect_skip_exit, no? > > Note the counter gets incremented even if we'd not consider the exit > because we have a later candidate already. > > I fear it's going to be quite random even with the debug counter. It is, I think the first counter is more useful. But in general the reason I kept the second counter which kinda does what was suggested in the RFC I sent before was that it should in theory at least allow us to test forcing of a PEELED case. Since we generally prefer the non-PEELED case if possible. At least that was the intention. Thanks, Tamar > > Can you see whether it really helps you? > > > && (!candidate > > || dominated_by_p (CDI_DOMINATORS, exit->src, > > candidate->src))) > > > > > > > > > > > > -- > Richard Biener <rguenther@suse.de> > SUSE Software Solutions Germany GmbH, > Frankenstrasse 146, 90461 Nuernberg, Germany; > GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
On Thu, 8 Feb 2024, Tamar Christina wrote: > > -----Original Message----- > > From: Richard Biener <rguenther@suse.de> > > Sent: Thursday, February 8, 2024 2:16 PM > > To: Tamar Christina <Tamar.Christina@arm.com> > > Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; jlaw@ventanamicro.com > > Subject: Re: [PATCH]middle-end: add two debug counters for early-break > > vectorization debugging > > > > On Thu, 8 Feb 2024, Tamar Christina wrote: > > > > > Hi All, > > > > > > This adds two new debug counter to aid in debugging early break code. > > > > > > - vect_force_last_exit: when reached will always force the final loop exit. > > > - vect_skip_exit: when reached will skip selecting the current candidate exit > > > as the loop exit. > > > > > > The first counter essentially allows you to turn off the PEELED case and the > > > second counter to pick a different exit, which may mean you pick no exit at > > > all. > > > > > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > > > > > Ok for master? > > > > > > Thanks, > > > Tamar > > > > > > gcc/ChangeLog: > > > > > > * dbgcnt.def (vect_force_last_exit, vect_skip_exit): New. > > > * tree-vect-loop.cc (vec_init_loop_exit_info): Use them. > > > > > > --- inline copy of patch -- > > > diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def > > > index > > ed9f062eac2c28c52df76b39d4312dd9fde1c800..8f7bebf93fceabdf6ae86c2df5 > > 91eae4848b8a5c 100644 > > > --- a/gcc/dbgcnt.def > > > +++ b/gcc/dbgcnt.def > > > @@ -213,5 +213,7 @@ DEBUG_COUNTER (stv_conversion) > > > DEBUG_COUNTER (tail_call) > > > DEBUG_COUNTER (tree_sra) > > > DEBUG_COUNTER (treepre_insert) > > > +DEBUG_COUNTER (vect_force_last_exit) > > > DEBUG_COUNTER (vect_loop) > > > +DEBUG_COUNTER (vect_skip_exit) > > > DEBUG_COUNTER (vect_slp) > > > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc > > > index > > eed2268e9bae7e7ad36d13da03e0b54eab26ef6f..854e9d78bc71721e6559a6bc > > 5dff78c813603a78 100644 > > > --- a/gcc/tree-vect-loop.cc > > > +++ b/gcc/tree-vect-loop.cc > > > @@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see > > > #include "tree-eh.h" > > > #include "case-cfn-macros.h" > > > #include "langhooks.h" > > > +#include "dbgcnt.h" > > > > > > /* Loop Vectorization Pass. > > > > > > @@ -977,6 +978,20 @@ vec_init_loop_exit_info (class loop *loop) > > > if (exits.length () == 1) > > > return exits[0]; > > > > > > + /* Check to see if we've been asked to force the last exit. */ > > > + if (!dbg_cnt (vect_force_last_exit)) > > > + { > > > + 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; > > > > Err, that's quite odd. Why not just below do > > > > > + } > > > + > > > /* If we have multiple exits we only support counting IV at the moment. > > > Analyze all exits and return the last one we can analyze. */ > > > class tree_niter_desc niter_desc; > > > @@ -998,6 +1013,7 @@ vec_init_loop_exit_info (class loop *loop) > > > && exit->src == single_pred (loop->latch) > > > && (integer_nonzerop (may_be_zero) > > > || COMPARISON_CLASS_P (may_be_zero)))) > > > + && dbg_cnt (vect_skip_exit) > > > > && (dbg_cnt (vect_force_last_exit) > > || exit->src == single_pred (loop->latch)) > > > > (also computed above already)? It's also oddly named, it's more like > > vect_allow_peeled_exit or so. > > Because this isn't deterministic. If a loop has n exits the above always forces > you to pick the final one regardless of n, rather than just skip consideration of an exit. Well, you can always do (before the loop) bool force_last_exit = dbg_cnt (vect_force_last_exit); to evaluate it only once. I think for debug counters we should avoid introducing more lines of code when possible (the above big odd blob). > And in that case is there a point in analyzing all the exits just to throw away the information? > > Doing in inside the consideration check would only skip one exit unless I'm misunderstanding. > > > > > It's also seemingly redundant with vect_skip_exit, no? > > > > Note the counter gets incremented even if we'd not consider the exit > > because we have a later candidate already. > > > > I fear it's going to be quite random even with the debug counter. > > It is, I think the first counter is more useful. But in general the reason I kept the second counter > which kinda does what was suggested in the RFC I sent before was that it should in theory at > least allow us to test forcing of a PEELED case. Since we generally prefer the non-PEELED case > if possible. > > At least that was the intention. For the PEELED case I wondered if a --param vect-allow-early-exit-peeled defaulted to 1 would make more sense. Of course it doesn't do this per loop. > Thanks, > Tamar > > > > > Can you see whether it really helps you? > > > > > && (!candidate > > > || dominated_by_p (CDI_DOMINATORS, exit->src, > > > candidate->src))) > > > > > > > > > > > > > > > > > > > -- > > Richard Biener <rguenther@suse.de> > > SUSE Software Solutions Germany GmbH, > > Frankenstrasse 146, 90461 Nuernberg, Germany; > > GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg) >
--- a/gcc/dbgcnt.def +++ b/gcc/dbgcnt.def @@ -213,5 +213,7 @@ DEBUG_COUNTER (stv_conversion) DEBUG_COUNTER (tail_call) DEBUG_COUNTER (tree_sra) DEBUG_COUNTER (treepre_insert) +DEBUG_COUNTER (vect_force_last_exit) DEBUG_COUNTER (vect_loop) +DEBUG_COUNTER (vect_skip_exit) DEBUG_COUNTER (vect_slp) diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index eed2268e9bae7e7ad36d13da03e0b54eab26ef6f..854e9d78bc71721e6559a6bc5dff78c813603a78 100644 --- a/gcc/tree-vect-loop.cc +++ b/gcc/tree-vect-loop.cc @@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see #include "tree-eh.h" #include "case-cfn-macros.h" #include "langhooks.h" +#include "dbgcnt.h" /* Loop Vectorization Pass. @@ -977,6 +978,20 @@ vec_init_loop_exit_info (class loop *loop) if (exits.length () == 1) return exits[0]; + /* Check to see if we've been asked to force the last exit. */ + if (!dbg_cnt (vect_force_last_exit)) + { + 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; + } + /* If we have multiple exits we only support counting IV at the moment. Analyze all exits and return the last one we can analyze. */ class tree_niter_desc niter_desc; @@ -998,6 +1013,7 @@ vec_init_loop_exit_info (class loop *loop) && exit->src == single_pred (loop->latch) && (integer_nonzerop (may_be_zero) || COMPARISON_CLASS_P (may_be_zero)))) + && dbg_cnt (vect_skip_exit) && (!candidate || dominated_by_p (CDI_DOMINATORS, exit->src, candidate->src)))