[Bug target/40457] New: use stm and ldm to access consecutive memory words

[Bug target/40457] New: use stm and ldm to access consecutive memory words

[carrot at google dot com]

Current gcc can't make use of stm and ldm to reduce code size.


-- 
           Summary: use stm and ldm to access consecutive memory words
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: carrot at google dot com
 GCC build triplet: i686-linux
  GCC host triplet: i686-linux
GCC target triplet: arm-eabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[carrot at google dot com]

------- Comment #1 from carrot at google dot com  2009-06-16 09:11 -------
Created an attachment (id=18005)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18005&action=view)
test case

For this function

void foo(int* p)
{
  p[0] = 1;
  p[1] = 2;
}

gcc generates:

mov     r1, #1
mov     r3, #2
str     r1, [r0]
str     r3, [r0, #4]
bx      lr

We use one stm instruction to replace two str instructions.

For the second case:

int bar(int* p)
{
  int x = p[0] + p[1];
  return x;
}

gcc generates:

ldr     r2, [r0, #4]
ldr     r3, [r0]
add     r0, r2, r3
bx      lr

In this case we can use on ldm to replace the two ldr instructions.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[ramana at gcc dot gnu dot org]

------- Comment #2 from ramana at gcc dot gnu dot org  2009-06-16 10:03 -------
Could you check to see why store_multiple_sequence doesn't find this in the
peephole in the ARM backend ? 

GCC does generate stm and ldm's in a number of other places using the old
peephole and store_multiple_sequence option. It might be worth digging into
this further. 


-- 

ramana at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |ramana at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-06-16 10:03:48
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2009-06-16 15:19 -------
I think these peepholes should moved over to peephole2 also if that area is
being touched.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
           Keywords|                            |missed-optimization


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[rearnsha at gcc dot gnu dot org]

------- Comment #4 from rearnsha at gcc dot gnu dot org  2009-06-16 15:50 -------
You haven't specified what compilation options you were using.


-- 

rearnsha at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rearnsha at gcc dot gnu dot
                   |                            |org
             Status|ASSIGNED                    |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[ubizjak at gmail dot com]

------- Comment #5 from ubizjak at gmail dot com  2009-06-16 18:16 -------
(In reply to comment #2)
> Could you check to see why store_multiple_sequence doesn't find this in the
> peephole in the ARM backend ? 

Registers also need to be consecutive, starting from certain register, i.e.:

str     r1, [r0]
str     r2, [r0, #4]

and

ldr     r3, [r0, #4]
ldr     r2, [r0]


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[rearnsha at arm dot com]

------- Comment #6 from rearnsha at arm dot com  2009-06-17 08:40 -------
Subject: Re:  use stm and ldm to access consecutive
        memory words

> ------- Comment #5 from ubizjak at gmail dot com  2009-06-16 18:16 -------
> Registers also need to be consecutive, starting from certain register, i.e.:
> 
> str     r1, [r0]
> str     r2, [r0, #4]

No, register numbers simply need to be ascending and loaded from
consecutive memory addresses, so {r0, r2, r3, r5} is valid, but {r2, r5,
r0, r3} is not.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[carrot at google dot com]

------- Comment #7 from carrot at google dot com  2009-06-17 09:30 -------
My command line option is -O2 -Os -mthumb

The compiler didn't run into load_multiple_sequence and
store_multiple_sequence. The peephole rules specified it applies to TARGET_ARM
only. Is there any special reason we didn't enable it in thumb mode?

For the ascending register number, do we have any code to rename a set of
registers to make them ascending? In the generated code for the second
function, the register numbers have different order compared with memory
offsets.

ldr     r2, [r0, #4]
ldr     r3, [r0]


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[ramana at gcc dot gnu dot org]

------- Comment #8 from ramana at gcc dot gnu dot org  2009-06-17 09:49 -------
(In reply to comment #7)
> My command line option is -O2 -Os -mthumb
> 
> The compiler didn't run into load_multiple_sequence and
> store_multiple_sequence. The peephole rules specified it applies to TARGET_ARM
> only. Is there any special reason we didn't enable it in thumb mode?

ldms and stms in thumb mode overwrite the base register that is used for
addresses and that's why this is not enabled for thumb mode. One could write a
peephole2 pattern that checked for liveness of the base register - if the base
register were dead after the instruction, then there could be an ldm or stm
peepholed.


> 
> For the ascending register number, do we have any code to rename a set of
> registers to make them ascending? In the generated code for the second
> function, the register numbers have different order compared with memory
> offsets.
> 
> ldr     r2, [r0, #4]
> ldr     r3, [r0]
> 

Not that I am aware of , it's as good as renaming but to allow combinations to
happen . It might be useful with PR9831 as well but is a separate problem. 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[ramana at gcc dot gnu dot org]

-- 

ramana at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |ASSIGNED
   Last reconfirmed|2009-06-16 10:03:48         |2009-06-19 10:18:34
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[ramana at gcc dot gnu dot org]

------- Comment #9 from ramana at gcc dot gnu dot org  2010-03-02 07:37 -------
Not working on this.


-- 

ramana at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|ramana at gcc dot gnu dot   |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[jiez at gcc dot gnu dot org]

-- 

jiez at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jiez at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[jiez at gcc dot gnu dot org]

------- Comment #10 from jiez at gcc dot gnu dot org  2010-03-16 09:08 -------
Not working on this.


-- 

jiez at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|jiez at gcc dot gnu dot org |unassigned at gcc dot gnu
                   |                            |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[bernds at codesourcery dot com]

------- Comment #11 from bernds at codesourcery dot com  2010-04-20 11:47 -------
http://gcc.gnu.org/ml/gcc-patches/2010-04/msg01231.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[bernds at gcc dot gnu dot org]

------- Comment #12 from bernds at gcc dot gnu dot org  2010-08-02 10:07 -------
Subject: Bug 40457

Author: bernds
Date: Mon Aug  2 10:06:47 2010
New Revision: 162815

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=162815
Log:
        PR target/40457
        * config/arm/arm.h (arm_regs_in_sequence): Declare.
        * config/arm/arm-protos.h (emit_ldm_seq, emit_stm_seq,
        load_multiple_sequence, store_multiple_sequence): Delete
        declarations.
        (arm_gen_load_multiple, arm_gen_store_multiple): Adjust
        declarations.
        * config/arm/ldmstm.md: New file.
        * config/arm/arm.c (arm_regs_in_sequence): New array.
        (load_multiple_sequence): Now static.  New args SAVED_ORDER,
        CHECK_REGS.  All callers changed.
        If SAVED_ORDER is nonnull, copy the computed order into it.
        If CHECK_REGS is false, don't sort REGS.  Handle Thumb mode.
        (store_multiple_sequence): Now static.  New args NOPS_TOTAL,
        SAVED_ORDER, REG_RTXS and CHECK_REGS.  All callers changed.
        If SAVED_ORDER is nonnull, copy the computed order into it.
        If CHECK_REGS is false, don't sort REGS.  Set up REG_RTXS just
        like REGS.  Handle Thumb mode.
        (arm_gen_load_multiple_1): New function, broken out of
        arm_gen_load_multiple.
        (arm_gen_store_multiple_1): New function, broken out of
        arm_gen_store_multiple.
        (arm_gen_multiple_op): New function, with code from
        arm_gen_load_multiple and arm_gen_store_multiple moved here.
        (arm_gen_load_multiple, arm_gen_store_multiple): Now just
        wrappers around arm_gen_multiple_op.  Remove argument UP, all callers
        changed.
        (gen_ldm_seq, gen_stm_seq, gen_const_stm_seq): New functions.
        * config/arm/predicates.md (commutative_binary_operator): New.
        (load_multiple_operation, store_multiple_operation): Handle more
        variants of these patterns with different starting offsets.  Handle
        Thumb-1.
        * config/arm/arm.md: Include "ldmstm.md".
        (ldmsi_postinc4, ldmsi_postinc4_thumb1, ldmsi_postinc3, ldmsi_postinc2,
        ldmsi4, ldmsi3, ldmsi2, stmsi_postinc4, stmsi_postinc4_thumb1,
        stmsi_postinc3, stmsi_postinc2, stmsi4, stmsi3, stmsi2 and related
        peepholes): Delete.
        * config/arm/ldmstm.md: New file.
        * config/arm/arm-ldmstm.ml: New file.

testsuite/
        PR target/40457
        * gcc.target/arm/pr40457-1.c: New test.
        * gcc.target/arm/pr40457-2.c: New test.


Added:
    trunk/gcc/config/arm/arm-ldmstm.ml
    trunk/gcc/config/arm/ldmstm.md
    trunk/gcc/testsuite/gcc.target/arm/pr40457-1.c
    trunk/gcc/testsuite/gcc.target/arm/pr40457-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/arm/arm-protos.h
    trunk/gcc/config/arm/arm.c
    trunk/gcc/config/arm/arm.h
    trunk/gcc/config/arm/arm.md
    trunk/gcc/config/arm/predicates.md
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

[Bug target/40457] use stm and ldm to access consecutive memory words

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

--- Comment #13 from Bernd Schmidt <bernds at gcc dot gnu.org> 2010-09-29 20:06:58 UTC ---
Author: bernds
Date: Wed Sep 29 20:06:55 2010
New Revision: 164732

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164732
Log:
    PR target/40457
    * postreload.c (move2add_use_add2_insn): Use full_costs for
    comparison.
    (move2add_use_add3_insn): Likewise.
    (reload_cse_move2add): Likewise.
    * rtlanal.c (get_full_rtx_cost): New function.
    * rtl.h (struct full_rtx_costs): New.
    (init_costs_to_max, init_costs_to_zero, costs_lt_p,
    costs_add_n_insns): New inline functions.
    (get_full_rtx_cost): Declare.

testsuite/
    PR target/40457
    * gcc.target/arm/pr40457-3.c: New test.


Added:
    trunk/gcc/testsuite/gcc.target/arm/pr40457-3.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/postreload.c
    trunk/gcc/rtl.h
    trunk/gcc/rtlanal.c
    trunk/gcc/testsuite/ChangeLog

[Bug target/40457] use stm and ldm to access consecutive memory words

[ramana at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |ramana at gcc dot gnu.org
         Resolution|                            |FIXED
   Target Milestone|---                         |4.6.0

--- Comment #14 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> 2011-02-01 01:10:53 UTC ---
Now fixed I think looking at the output from trunk.

[Bug target/40457] use stm and ldm to access consecutive memory words

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40457

--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alexandre Oliva <aoliva@gcc.gnu.org>:

https://gcc.gnu.org/g:acddf6665f067bc98a2529a699b1d4509a7387cb

commit r13-5160-gacddf6665f067bc98a2529a699b1d4509a7387cb
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Fri Jan 13 21:15:41 2023 -0300

    [PR40457] [arm] expand SI-aligned movdi into pair of movsi

    When expanding a misaligned DImode move, emit aligned SImode moves if
    the parts are sufficiently aligned.  This enables neighboring stores
    to be peephole-combined into stm, as expected by the PR40457 testcase,
    even after SLP vectorizes the originally aligned SImode stores into a
    misaligned DImode store.


    for  gcc/ChangeLog

            PR target/40457
            * config/arm/arm.md (movmisaligndi): Prefer aligned SImode
            moves.