[Bug target/45094] New: [arm] wrong instructions for dword move in some cases

[Bug target/45094] New: [arm] wrong instructions for dword move in some cases

[akos dot pasztory at gmail dot com]

gcc 4.5.0

$ cat /tmp/bug.c
extern int printf(const char *fmt, ...);
void foo(void *x) { printf("%p\n", x); }
void bar(long long *x) { printf("%lld ", *x); foo(x); }

int main()
{
        bar(&(long long){0ll});
        bar(&(long long){1ll});
        bar(&(long long){2ll});
        bar(&(long long){3ll});
        bar(&(long long){4ll});
        bar(&(long long){5ll});
        bar(&(long long){6ll});
        bar(&(long long){7ll});
        bar(&(long long){8ll});
        bar(&(long long){9ll});
        bar(&(long long){10ll});
        bar(&(long long){11ll});
        bar(&(long long){12ll});
        bar(&(long long){13ll});
        bar(&(long long){14ll});
        bar(&(long long){15ll});
        bar(&(long long){16ll});
        bar(&(long long){17ll});
        bar(&(long long){18ll});
        bar(&(long long){19ll});
        bar(&(long long){20ll});
        bar(&(long long){21ll});
        bar(&(long long){22ll});
        bar(&(long long){23ll});
        bar(&(long long){24ll});
        bar(&(long long){25ll});
        bar(&(long long){26ll});
        bar(&(long long){27ll});
        bar(&(long long){28ll});
        bar(&(long long){29ll});
        bar(&(long long){30ll});
        bar(&(long long){31ll});
        bar(&(long long){32ll});
        bar(&(long long){33ll});
        bar(&(long long){34ll});
        bar(&(long long){35ll});
        bar(&(long long){36ll});
        bar(&(long long){37ll});
        bar(&(long long){38ll});
        bar(&(long long){39ll});
        bar(&(long long){40ll});
        bar(&(long long){41ll});
        bar(&(long long){42ll});
        bar(&(long long){43ll});
        bar(&(long long){44ll});
        return 0;
}

$ cc -mcpu=cortex-a8 -mfpu=neon -mfloat-abi=softfp -S -O2 /tmp/bug.c

inspect bug.s.  for a while gcc emits correct instructions:

...
        mov     r2, #29
        mov     r3, #0
        strd    r2, [r0, #-240]!
        bl      bar
        add     r0, sp, #360
        mov     r2, #30
        mov     r3, #0
        strd    r2, [r0, #-248]!
        bl      bar

however when reaching offset -256, it emits LDRs instead of STRs:

        add     r0, sp, #360
        mov     r2, #31
        mov     r3, #0
        ldr     r2, [r0, #-256]!
        ldr     r3, [r0, #4]
        bl      bar

the issue seems to be a typo in gcc/config/arm/arm.c:output_move_double()
introduced by commit [1].  i've tried to fix by applying the following:

--- ../gcc-4.5.0/gcc/config/arm/arm.c.orig      2010-07-27 14:22:42.000000000
+0300
+++ ../gcc-4.5.0/gcc/config/arm/arm.c   2010-07-27 14:23:05.000000000 +0300
@@ -12182,13 +12182,13 @@ output_move_double (rtx *operands)
            {
              if (GET_CODE (XEXP (operands[0], 0)) == PRE_MODIFY)
                {
-                 output_asm_insn ("ldr%?\t%0, [%1, %2]!", otherops);
-                 output_asm_insn ("ldr%?\t%H0, [%1, #4]", otherops);
+                 output_asm_insn ("str%?\t%0, [%1, %2]!", otherops);
+                 output_asm_insn ("str%?\t%H0, [%1, #4]", otherops);
                }
              else
                {
-                 output_asm_insn ("ldr%?\t%H0, [%1, #4]", otherops);
-                 output_asm_insn ("ldr%?\t%0, [%1], %2", otherops);
+                 output_asm_insn ("str%?\t%H0, [%1, #4]", otherops);
+                 output_asm_insn ("str%?\t%0, [%1], %2", otherops);
                }
            }
          else if (GET_CODE (XEXP (operands[0], 0)) == PRE_MODIFY)

[1]
http://repo.or.cz/w/official-gcc.git/commitdiff/f1225f6f0f9b7acb3a64314f2113807ebeea5abf?hp=78f46d4510475cdb9532b10787e82b476c9eeef1


-- 
           Summary: [arm] wrong instructions for dword move in some cases
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: akos dot pasztory at gmail dot com
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: arm-linux-gnueabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[ramana at gcc dot gnu dot org]

------- Comment #1 from ramana at gcc dot gnu dot org  2010-07-27 12:47 -------
Patches should be submitted to gcc-patches@gcc.gnu.org after having been
regression tested. Please also submit a testcase and appropriate Changelog
entries as documented here -  http://gcc.gnu.org/contribute.html#patches


Having said that however, this patch looks alright to me from the naked eye and
code inspection.


-- 

ramana at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2010-07-27 12:47:57
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[siarhei dot siamashka at gmail dot com]

------- Comment #2 from siarhei dot siamashka at gmail dot com  2010-07-27 20:07 -------
Created an attachment (id=21327)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21327&action=view)
simplified testcase

Confirmed with gcc 4.5.0 here. Also tried but could not reproduce the problem
with gcc 4.4 (it just does not seem to be able to emit ldrd/strd instructions
with pre/post increment).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[qiyao at gcc dot gnu dot org]

------- Comment #3 from qiyao at gcc dot gnu dot org  2010-08-01 08:44 -------
(In reply to comment #2)
> Created an attachment (id=21327)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21327&action=view) [edit]
> simplified testcase

Update this test case a little bit, with test commands.
Post patch here http://gcc.gnu.org/ml/gcc-patches/2010-08/msg00001.html



-- 

qiyao at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |qiyao at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[akos dot pasztory at gmail dot com]

------- Comment #4 from akos dot pasztory at gmail dot com  2010-08-01 11:18 -------
> Post patch here http://gcc.gnu.org/ml/gcc-patches/2010-08/msg00001.html

+                 output_asm_insn ("strr%?\t%H0, [%1, #4]", otherops);

s/strr/str/ ?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[qiyao at gcc dot gnu dot org]

------- Comment #5 from qiyao at gcc dot gnu dot org  2010-08-02 00:38 -------
(In reply to comment #4)
> > Post patch here http://gcc.gnu.org/ml/gcc-patches/2010-08/msg00001.html
> 
> +                 output_asm_insn ("strr%?\t%H0, [%1, #4]", otherops);
> 
> s/strr/str/ ?
> 
Right, it is a typo.  Latest patch is posted here,
http://gcc.gnu.org/ml/gcc-patches/2010-08/msg00018.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[qiyao at gcc dot gnu dot org]

------- Comment #6 from qiyao at gcc dot gnu dot org  2010-08-18 12:34 -------
Subject: Bug 45094

Author: qiyao
Date: Wed Aug 18 12:33:43 2010
New Revision: 163338

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=163338
Log:
gcc/
        PR target/45094
        * config/arm/arm.c (output_move_double): Fix typo generating 
        instructions ('ldr'->'str').

gcc/testsuite/

        PR target/45094
        * gcc.target/arm/pr45094.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/arm/pr45094.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/arm/arm.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094

[Bug target/45094] [arm] wrong instructions for dword move in some cases

[ramana at gcc dot gnu dot org]

------- Comment #7 from ramana at gcc dot gnu dot org  2010-08-27 12:14 -------
can this be backported to the 4.5 branch please ? 


-- 

ramana at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.5.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45094