From: Corey Minyard <minyard@acm.org>
To: Richard Henderson <rth@redhat.com>
Cc: gcc@gcc.gnu.org
Subject: Re: Loop optimization bug with Ada front end on PPC (and probably Alpha)
Date: Fri, 16 Nov 2001 03:42:00 -0000 [thread overview]
Message-ID: <3C01C4F3.2020403@acm.org> (raw)
In-Reply-To: <20011125175500.A11474@redhat.com>
That patch looks a lot better than mine :-). However, I'm getting a
segv compiling unwind-dw2-fde.c. I put a print in (I can't use gdb 5.0
with the output of gcc 3.0 on Linux PowerPC), and it's dying in the line:
&& INSN_IN_RANGE_P (JUMP_LABEL (insn), loop->top, loop->cont)
It looks like loop->top is alway NULL. I'm working with a slightly old
CVS, maybe I should update, or is this a real problem?
-Corey
Richard Henderson wrote:
>The problem is not limited to doloop -- the unroller ought
>to hit this problem as well. I'm testing the following.
>
>
>
>r~
>
>
>
>Index: loop.c
>===================================================================
>RCS file: /cvs/gcc/gcc/gcc/loop.c,v
>retrieving revision 1.369
>diff -c -p -d -r1.369 loop.c
>*** loop.c 2001/11/15 23:44:56 1.369
>--- loop.c 2001/11/26 01:52:34
>*************** typedef struct loop_replace_args
>*** 282,293 ****
> rtx insn;
> } loop_replace_args;
>
>- /* Nonzero iff INSN is between START and END, inclusive. */
>- #define INSN_IN_RANGE_P(INSN, START, END) \
>- (INSN_UID (INSN) < max_uid_for_loop \
>- && INSN_LUID (INSN) >= INSN_LUID (START) \
>- && INSN_LUID (INSN) <= INSN_LUID (END))
>-
> /* Indirect_jump_in_function is computed once per function. */
> static int indirect_jump_in_function;
> static int indirect_jump_in_function_p PARAMS ((rtx));
>--- 282,287 ----
>Index: loop.h
>===================================================================
>RCS file: /cvs/gcc/gcc/gcc/loop.h,v
>retrieving revision 1.56
>diff -c -p -d -r1.56 loop.h
>*** loop.h 2001/10/29 22:13:40 1.56
>--- loop.h 2001/11/26 01:52:34
>*************** Software Foundation, 59 Temple Place - S
>*** 50,55 ****
>--- 50,60 ----
> #define REGNO_FIRST_LUID(REGNO) uid_luid[REGNO_FIRST_UID (REGNO)]
> #define REGNO_LAST_LUID(REGNO) uid_luid[REGNO_LAST_UID (REGNO)]
>
>+ /* Nonzero iff INSN is between START and END, inclusive. */
>+ #define INSN_IN_RANGE_P(INSN, START, END) \
>+ (INSN_UID (INSN) < max_uid_for_loop \
>+ && INSN_LUID (INSN) >= INSN_LUID (START) \
>+ && INSN_LUID (INSN) <= INSN_LUID (END))
>
> /* A "basic induction variable" or biv is a pseudo reg that is set
> (within this loop) only by incrementing or decrementing it. */
>Index: unroll.c
>===================================================================
>RCS file: /cvs/gcc/gcc/gcc/unroll.c,v
>retrieving revision 1.147
>diff -c -p -d -r1.147 unroll.c
>*** unroll.c 2001/11/21 00:50:56 1.147
>--- unroll.c 2001/11/26 01:52:34
>*************** loop_iterations (loop)
>*** 3480,3485 ****
>--- 3480,3486 ----
> int unsigned_p, compare_dir, final_larger;
> rtx last_loop_insn;
> rtx reg_term;
>+ rtx insn;
> struct iv_class *bl;
>
> loop_info->n_iterations = 0;
>*************** loop_iterations (loop)
>*** 3705,3710 ****
>--- 3706,3762 ----
>
> if (initial_value == 0)
> return 0;
>+
>+ /* Some code transformations can result in code akin to
>+
>+ LOOP_BEG
>+ goto start;
>+ top:
>+ i++;
>+ start:
>+ ...
>+ LOOP_CONT
>+ if (i < n) goto top;
>+ LOOP_END
>+
>+ In this situation, we skip the increment the first time through
>+ the loop, which results in an incorrect estimate of the number
>+ of iterations. As we did for GIVs above, adjust the initial value
>+ to compensate. */
>+
>+ off_by_one = 0;
>+ for (insn = loop->start; insn != loop->top; insn = NEXT_INSN (insn))
>+ if (GET_CODE (insn) == JUMP_INSN)
>+ {
>+ if (any_uncondjump_p (insn)
>+ && JUMP_LABEL (insn)
>+ && INSN_IN_RANGE_P (JUMP_LABEL (insn), loop->top, loop->cont))
>+ {
>+ if (reg_set_between_p (bl->biv->src_reg, insn, JUMP_LABEL (insn)))
>+ off_by_one = 1;
>+ break;
>+ }
>+ /* No idea what's going on. */
>+ if (loop_dump_stream)
>+ fprintf (loop_dump_stream,
>+ "Loop iterations: Confused by jump before loop top.\n");
>+ return 0;
>+ }
>+
>+ if (off_by_one)
>+ {
>+ if (loop_dump_stream)
>+ fprintf (loop_dump_stream,
>+ "Loop iterations: Basic induction var skips initial incr.\n");
>+ if (GET_CODE (increment) != CONST_INT)
>+ {
>+ if (loop_dump_stream)
>+ fprintf (loop_dump_stream,
>+ "Loop iterations: Can't adjust with non-constant incr.\n");
>+ return 0;
>+ }
>+ initial_value = plus_constant (initial_value, -INTVAL (increment));
>+ }
>
> unsigned_p = 0;
> off_by_one = 0;
>
WARNING: multiple messages have this Message-ID
From: Corey Minyard <minyard@acm.org>
To: Richard Henderson <rth@redhat.com>
Cc: gcc@gcc.gnu.org
Subject: Re: Loop optimization bug with Ada front end on PPC (and probably Alpha)
Date: Sun, 25 Nov 2001 20:27:00 -0000 [thread overview]
Message-ID: <3C01C4F3.2020403@acm.org> (raw)
Message-ID: <20011125202700.jamJQYhOgOxswuevWTkbnP9TVaCDi13BP173H702Jbw@z> (raw)
In-Reply-To: <20011125175500.A11474@redhat.com>
That patch looks a lot better than mine :-). However, I'm getting a
segv compiling unwind-dw2-fde.c. I put a print in (I can't use gdb 5.0
with the output of gcc 3.0 on Linux PowerPC), and it's dying in the line:
&& INSN_IN_RANGE_P (JUMP_LABEL (insn), loop->top, loop->cont)
It looks like loop->top is alway NULL. I'm working with a slightly old
CVS, maybe I should update, or is this a real problem?
-Corey
Richard Henderson wrote:
>The problem is not limited to doloop -- the unroller ought
>to hit this problem as well. I'm testing the following.
>
>
>
>r~
>
>
>
>Index: loop.c
>===================================================================
>RCS file: /cvs/gcc/gcc/gcc/loop.c,v
>retrieving revision 1.369
>diff -c -p -d -r1.369 loop.c
>*** loop.c 2001/11/15 23:44:56 1.369
>--- loop.c 2001/11/26 01:52:34
>*************** typedef struct loop_replace_args
>*** 282,293 ****
> rtx insn;
> } loop_replace_args;
>
>- /* Nonzero iff INSN is between START and END, inclusive. */
>- #define INSN_IN_RANGE_P(INSN, START, END) \
>- (INSN_UID (INSN) < max_uid_for_loop \
>- && INSN_LUID (INSN) >= INSN_LUID (START) \
>- && INSN_LUID (INSN) <= INSN_LUID (END))
>-
> /* Indirect_jump_in_function is computed once per function. */
> static int indirect_jump_in_function;
> static int indirect_jump_in_function_p PARAMS ((rtx));
>--- 282,287 ----
>Index: loop.h
>===================================================================
>RCS file: /cvs/gcc/gcc/gcc/loop.h,v
>retrieving revision 1.56
>diff -c -p -d -r1.56 loop.h
>*** loop.h 2001/10/29 22:13:40 1.56
>--- loop.h 2001/11/26 01:52:34
>*************** Software Foundation, 59 Temple Place - S
>*** 50,55 ****
>--- 50,60 ----
> #define REGNO_FIRST_LUID(REGNO) uid_luid[REGNO_FIRST_UID (REGNO)]
> #define REGNO_LAST_LUID(REGNO) uid_luid[REGNO_LAST_UID (REGNO)]
>
>+ /* Nonzero iff INSN is between START and END, inclusive. */
>+ #define INSN_IN_RANGE_P(INSN, START, END) \
>+ (INSN_UID (INSN) < max_uid_for_loop \
>+ && INSN_LUID (INSN) >= INSN_LUID (START) \
>+ && INSN_LUID (INSN) <= INSN_LUID (END))
>
> /* A "basic induction variable" or biv is a pseudo reg that is set
> (within this loop) only by incrementing or decrementing it. */
>Index: unroll.c
>===================================================================
>RCS file: /cvs/gcc/gcc/gcc/unroll.c,v
>retrieving revision 1.147
>diff -c -p -d -r1.147 unroll.c
>*** unroll.c 2001/11/21 00:50:56 1.147
>--- unroll.c 2001/11/26 01:52:34
>*************** loop_iterations (loop)
>*** 3480,3485 ****
>--- 3480,3486 ----
> int unsigned_p, compare_dir, final_larger;
> rtx last_loop_insn;
> rtx reg_term;
>+ rtx insn;
> struct iv_class *bl;
>
> loop_info->n_iterations = 0;
>*************** loop_iterations (loop)
>*** 3705,3710 ****
>--- 3706,3762 ----
>
> if (initial_value == 0)
> return 0;
>+
>+ /* Some code transformations can result in code akin to
>+
>+ LOOP_BEG
>+ goto start;
>+ top:
>+ i++;
>+ start:
>+ ...
>+ LOOP_CONT
>+ if (i < n) goto top;
>+ LOOP_END
>+
>+ In this situation, we skip the increment the first time through
>+ the loop, which results in an incorrect estimate of the number
>+ of iterations. As we did for GIVs above, adjust the initial value
>+ to compensate. */
>+
>+ off_by_one = 0;
>+ for (insn = loop->start; insn != loop->top; insn = NEXT_INSN (insn))
>+ if (GET_CODE (insn) == JUMP_INSN)
>+ {
>+ if (any_uncondjump_p (insn)
>+ && JUMP_LABEL (insn)
>+ && INSN_IN_RANGE_P (JUMP_LABEL (insn), loop->top, loop->cont))
>+ {
>+ if (reg_set_between_p (bl->biv->src_reg, insn, JUMP_LABEL (insn)))
>+ off_by_one = 1;
>+ break;
>+ }
>+ /* No idea what's going on. */
>+ if (loop_dump_stream)
>+ fprintf (loop_dump_stream,
>+ "Loop iterations: Confused by jump before loop top.\n");
>+ return 0;
>+ }
>+
>+ if (off_by_one)
>+ {
>+ if (loop_dump_stream)
>+ fprintf (loop_dump_stream,
>+ "Loop iterations: Basic induction var skips initial incr.\n");
>+ if (GET_CODE (increment) != CONST_INT)
>+ {
>+ if (loop_dump_stream)
>+ fprintf (loop_dump_stream,
>+ "Loop iterations: Can't adjust with non-constant incr.\n");
>+ return 0;
>+ }
>+ initial_value = plus_constant (initial_value, -INTVAL (increment));
>+ }
>
> unsigned_p = 0;
> off_by_one = 0;
>
next prev parent reply other threads:[~2001-11-26 4:27 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-11-13 5:20 Corey Minyard
2001-11-13 6:05 ` David Edelsohn
2001-11-14 8:05 ` Corey Minyard
2001-11-13 8:02 ` guerby
2001-11-13 9:48 ` Corey Minyard
2001-11-16 22:19 ` David Edelsohn
2001-11-26 7:39 ` David Edelsohn
2001-11-15 0:48 ` Richard Henderson
2001-11-15 14:19 ` Andreas Schwab
2001-11-15 16:20 ` Richard Henderson
2001-11-25 12:23 ` Richard Henderson
2001-11-18 9:18 ` Richard Henderson
2001-11-27 0:02 ` Richard Henderson
2001-11-25 8:57 ` Andreas Schwab
2001-11-15 18:02 ` Corey Minyard
2001-11-15 19:37 ` Richard Henderson
2001-11-25 15:52 ` Richard Henderson
2001-11-16 3:13 ` Richard Henderson
2001-11-16 3:42 ` Corey Minyard [this message]
2001-11-16 8:54 ` Bryce McKinlay
2001-11-26 0:47 ` Bryce McKinlay
2001-11-25 20:27 ` Corey Minyard
2001-11-17 1:33 ` Corey Minyard
2001-11-17 6:09 ` Corey Minyard
2001-11-26 10:22 ` Corey Minyard
2001-11-17 11:51 ` Richard Henderson
2001-11-17 15:20 ` Corey Minyard
2001-11-26 14:45 ` Corey Minyard
2001-11-18 5:15 ` Corey Minyard
2001-11-18 8:59 ` Richard Henderson
2001-11-19 2:58 ` Corey Minyard
2001-11-19 3:11 ` Richard Henderson
2001-11-19 5:36 ` Corey Minyard
2001-11-19 7:48 ` Richard Henderson
2001-11-19 7:58 ` Corey Minyard
2001-11-19 9:43 ` Richard Henderson
2001-11-19 12:44 ` Corey Minyard
2001-11-19 13:53 ` Richard Henderson
2001-11-20 11:20 ` Corey Minyard
2001-11-27 19:57 ` Corey Minyard
2001-11-27 15:31 ` Richard Henderson
2001-11-27 15:04 ` Corey Minyard
2001-11-27 14:27 ` Richard Henderson
2001-11-27 13:25 ` Corey Minyard
2001-11-27 12:58 ` Richard Henderson
2001-11-27 11:51 ` Corey Minyard
2001-11-27 10:29 ` Richard Henderson
2001-11-27 10:08 ` Corey Minyard
2001-11-26 23:18 ` Richard Henderson
2001-11-26 17:15 ` Corey Minyard
2001-11-26 13:49 ` Richard Henderson
2001-11-26 8:58 ` Corey Minyard
2001-11-25 17:58 ` Richard Henderson
2001-11-25 15:06 ` Corey Minyard
2001-11-15 18:47 Richard Kenner
2001-11-25 15:13 ` Richard Kenner
2001-11-15 19:05 dewar
2001-11-25 15:20 ` dewar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3C01C4F3.2020403@acm.org \
--to=minyard@acm.org \
--cc=gcc@gcc.gnu.org \
--cc=rth@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).