[Bug inline-asm/64681] New: gcc assign wrong register for arm inline assembly

[Bug inline-asm/64681] New: gcc assign wrong register for arm inline assembly

[zhongwei.yao at arm dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64681

            Bug ID: 64681
           Summary: gcc assign wrong register for arm inline assembly
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: blocker
          Priority: P3
         Component: inline-asm
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhongwei.yao at arm dot com

Created attachment 34492
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34492&action=edit
all related file.

I compile following code on linux by arm-linux-androideabi-gcc (gcc version 4.9
20140827) with following command:

 arm-linux-androideabi-g++ -mfloat-abi=softfp -mfpu=neon -mthumb -Wall -Wextra
-march=armv7-a --sysroot=$ndk/platforms/android-21/arch-arm -O2 -Wall main.cpp

==c code start==
#include <arm_neon.h>

int main(void) {
  return 0;
}

char buffer[32];

void bar(int n) {
  int j = 0;
  int64x1_t s = vdup_n_s64(0);
  int64x1_t onev = vdup_n_s64(1);
  int64_t sum = 0;

  for (j = 0; j <= n; j++) {
    asm ("vsub.s64 %0, %0, d1"
          : "+w" (s): : "memory");
  }
  sum = (int64_t)j;
  sum >>= vget_lane_s64(s, 0);
  if(sum >0)
    s = vsub_s64(s, onev);
  vst1_s64((int64_t*)buffer, s);
}
==code end==

It returns:
/tmp/ccE0j9sL.s: Assembler messages:
/tmp/ccE0j9sL.s:55: Error: invalid instruction shape -- `vsub.s64 s14,s14,d1'

I think it is the bug in gcc that assign wrong register for variable s. It
should be d14 here, while it assignes s14.

The generated assembly file is:

==asm code start==
    .syntax unified
    .arch armv7-a
    .eabi_attribute 27, 3
    .fpu neon
    .eabi_attribute 20, 1
    .eabi_attribute 21, 1
    .eabi_attribute 23, 3
    .eabi_attribute 24, 1
    .eabi_attribute 25, 1
    .eabi_attribute 26, 2
    .eabi_attribute 30, 2
    .eabi_attribute 34, 1
    .eabi_attribute 18, 4
    .thumb
    .file    "main.cpp"
    .section    .text.startup,"ax",%progbits
    .align    2
    .global    main
    .thumb
    .thumb_func
    .type    main, %function
main:
    .fnstart
.LFB1870:
    @ args = 0, pretend = 0, frame = 0
    @ frame_needed = 0, uses_anonymous_args = 0
    @ link register save eliminated.
    movs    r0, #0
    bx    lr
    .cantunwind
    .fnend
    .size    main, .-main
    .text
    .align    2
    .global    _Z3bari
    .thumb
    .thumb_func
    .type    _Z3bari, %function
_Z3bari:
    .fnstart
.LFB1871:
    @ args = 0, pretend = 0, frame = 0
    @ frame_needed = 0, uses_anonymous_args = 0
    cmp    r0, #0
    vmov.i32    d7, #0  @ di
    push    {lr}
    blt    .L5
    adds    r0, r0, #1
    movs    r2, #0
.L4:
    adds    r2, r2, #1
    cmp    r2, r0
#APP
@ 17 "src/main.cpp" 1
    vsub.s64 s14, s14, d1
@ 0 "" 2
    .thumb
    bne    .L4
    fmrs    r1, s14    @ int
    asrs    r3, r2, #31
    rsb    r0, r1, #32
    subs    lr, r1, #32
    lsl    r0, r3, r0
    lsr    r2, r2, r1
    it    pl
    asrpl    lr, r3, lr
    orr    r2, r2, r0
    it    pl
    orrpl    r2, r2, lr
    asrs    r3, r3, r1
    cmp    r2, #1
    sbcs    r3, r3, #0
    blt    .L5
    vmov.i32    d16, #0xffffffff  @ di
    vadd.i64    d7, d7, d16
.L5:
    ldr    r3, .L10
.LPIC1:
    add    r3, pc
    ldr    r3, [r3]
    vst1.64    {d7}, [r3:64]
    ldr    pc, [sp], #4
.L11:
    .align    2
.L10:
    .word    buffer(GOT_PREL)+(.-(.LPIC1+4))
    .cantunwind
    .fnend
    .size    _Z3bari, .-_Z3bari
    .global    buffer
    .bss
    .align    3
    .type    buffer, %object
    .size    buffer, 32
buffer:
    .space    32
    .ident    "GCC: (GNU) 4.9 20140827 (prerelease)"
    .section    .note.GNU-stack,"",%progbits
==asm code end==

[Bug inline-asm/64681] gcc assign wrong register for arm inline assembly

[schwab@linux-m68k.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64681

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|blocker                     |normal

--- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> ---
You need to format the operand as %P0.

[Bug inline-asm/64681] gcc assign wrong register for arm inline assembly

[zhongwei.yao at arm dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64681

zhongwei.yao <zhongwei.yao at arm dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |---

--- Comment #3 from zhongwei.yao <zhongwei.yao at arm dot com> ---
(In reply to Andreas Schwab from comment #1)
> You need to format the operand as %P0.

Hi, Andreas, Thanks for pointing out this. Is this syntax documented in GCC
doc?

[Bug inline-asm/64681] gcc assign wrong register for arm inline assembly

[gccbugzilla at limegreensocks dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64681

David <gccbugzilla at limegreensocks dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gccbugzilla@limegreensocks.
                   |                            |com

--- Comment #4 from David <gccbugzilla at limegreensocks dot com> ---
Until very recently, *none* of the modifiers were documented.  In the current
docs
(https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#i386Operandmodifiers),
only the i386 modifiers are doc'ed.

That said, you can always check out the gcc source.  For example:

The comments above output_asm_insn in
https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/final.c?view=co&content-type=text%2Fplain
describe some global modifiers.

For i386-specific modifiers, look above ix86_print_operand in
https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/config/i386/i386.c?view=co&content-type=text%2Fplain

For arm, look above arm_print_operand in
https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/config/arm/arm.c?view=co&content-type=text%2Fplain

Presumably there are similar sections for other configs.

[Bug inline-asm/64681] Document print modifiers for ARM

[ramana at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64681

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |documentation
             Target|                            |arm*
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-01-26
                 CC|                            |ramana at gcc dot gnu.org
            Summary|gcc assign wrong register   |Document print modifiers
                   |for arm inline assembly     |for ARM
     Ever confirmed|0                           |1

[Bug inline-asm/64681] Document print modifiers for ARM

[zhongwei.yao at arm dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64681

zhongwei.yao <zhongwei.yao at arm dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WORKSFORME

--- Comment #5 from zhongwei.yao <zhongwei.yao at arm dot com> ---
(In reply to David from comment #4)
> Until very recently, *none* of the modifiers were documented.  In the
> current docs
> (https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#i386Operandmodifiers),
> only the i386 modifiers are doc'ed.
> 
> That said, you can always check out the gcc source.  For example:
> 
> The comments above output_asm_insn in
> https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/final.c?view=co&content-
> type=text%2Fplain describe some global modifiers.
> 
> For i386-specific modifiers, look above ix86_print_operand in
> https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/config/i386/i386.c?view=co&content-
> type=text%2Fplain
> 
> For arm, look above arm_print_operand in
> https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/config/arm/arm.c?view=co&content-
> type=text%2Fplain
> 
> Presumably there are similar sections for other configs.

Thanks!