sh-coff-objdump cannot disassemble DSP instructions

sh-coff-objdump cannot disassemble DSP instructions

[Arati Dikey]

hi !

The sh-coff-objdump cannot disassemble DSP instructions 
while the sh-elf-objdump does so. It simply interprets them as data
(.word) 

After digging thru' the source code, I think that
this is because the assembler (sh-coff-as)
stores the bfd architecture as 'sh' and not 'sh-dsp'  (arch =
bfd_arch_sh , machine = 0).

The 'static int sh_dsp' in tc-sh.c is set when -dsp option is given to
assembler. 
How do I store this value in the bfd info ?

I have read the BFD manual but am still not sure
how and where to make modifications in the bfd backend. 

Any help/guidance on this will be greatly appreciated.

Regards,
Arati Dikey


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Re: sh-coff-objdump cannot disassemble DSP instructions

[Nick Clifton]

Hi Arati,

> The sh-coff-objdump cannot disassemble DSP instructions  
> while the sh-elf-objdump does so. It simply interprets them as data
> (.word)

Which version of binutils are you using ?  The current sources do not
appear to exhibit this behaviour.

> The 'static int sh_dsp' in tc-sh.c is set when -dsp option is given
> to assembler.  How do I store this value in the bfd info ?

By calling bfd_set_arch_mach().  For example you might do something
like this:

  bfd_set_arch_mach (stdoutput, TARGET_ARCH,
        sh_dsp ? bfd_mach_sh_dsp : bfd_mach_sh);

in gas/config/tc-sh.c:md_begin().

Cheers
        Nick

Re: sh-coff-objdump cannot disassemble DSP instructions

[Joern Rennecke]

Arati Dikey wrote:
> 
> hi !
> 
> The sh-coff-objdump cannot disassemble DSP instructions
> while the sh-elf-objdump does so. It simply interprets them as data
> (.word)

sh-elf stores the 'mach'(ine) information in the elf flags.  We have
no matching mechanism in place for sh-coff.  Hence objdump has no
way to tell what SH variant the code is for.  Note that sh-dsp
/ sh3-dsp use 0xfxxx opcodes for dsp instructions that are used by
the sh3e / sh4 or floating point, so there is no all-encompassing
instruction set that we could use.  We'd have to implement a way
to store the mach value for sh-coff.  That is, if we care about
not having to specify -msh_dsp to objdump when using coff for sh-dsp.
	
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RE: sh-coff-objdump cannot disassemble DSP instructions

[Arati Dikey]

Thanks Nick.
I am using the latest binutils sources. (GNU objdump 020106 20020106).
My test program is as follows.
test.s
	movs.w @-R4, A0
	mov.b   @r2,r3

sh-coff-as -dsp test.s -o test-coff.o
sh-coff-objdump -D test.coff.o -EB

the output is	
start-coff-o:     file format coff-shl

Disassembly of section .text:

00000000 <.text>:
   0:	f4 70       	.word 0xf470
   2:	63 20       	mov.b	@r2,r3
	...
Disassembly of section .data:

Now my problem is as follows.
1. I am not sure whether it is the assembler or the objdump utility
which needs to be changed.
2. Thinking its the assembler, I made following changes.
    1. tc-sh.h 
         extern int sh_dsp ;
	   #define TARGET_MACH_DSP (sh_dsp ? 1 : 0 )
    2. In obj-coff.c,
         in function write_object_file() I inserted the foll. code.
         #ifdef TARGET_MACH_DSP
  		bfd_set_arch_mach (abfd, BFD_ARCH, bfd_mach_sh_dsp);
	  #else
  		bfd_set_arch_mach (abfd, BFD_ARCH, machine);
	  #endif
   3. Removed the static qualifier to 'sh_dsp' in tc_sh.c
   4. Then, thru' gdb I verified the value of abfd->arch_info just
before bfd_write()
      and it displays everything correctly. (arch = bfd_arch_sh, mach =
45, arch_name = "sh",
      printable_name = "sh_dsp')
   5. Despite this, sh-coff-objdump produces the *same* wrong result.
   6. Incidently, if you supply -msh_dsp to sh-coff-objdump, it works
fine. But -m is an optional 	argument. And it works properly in
sh-elf-objdump w/o the -m option. 

I am not sure how to proceed. Please guide me.

Regards,
Arati 


-----Original Message-----
From: Nick Clifton [mailto:nickc@cambridge.redhat.com]
Sent: Tuesday, January 15, 2002 8:36 PM
To: Arati Dikey
Cc: binutils@sources.redhat.com
Subject: Re: sh-coff-objdump cannot disassemble DSP instructions


Hi Arati,

> The sh-coff-objdump cannot disassemble DSP instructions  
> while the sh-elf-objdump does so. It simply interprets them as data
> (.word)

Which version of binutils are you using ?  The current sources do not
appear to exhibit this behaviour.

> The 'static int sh_dsp' in tc-sh.c is set when -dsp option is given
> to assembler.  How do I store this value in the bfd info ?

By calling bfd_set_arch_mach().  For example you might do something
like this:

  bfd_set_arch_mach (stdoutput, TARGET_ARCH,
        sh_dsp ? bfd_mach_sh_dsp : bfd_mach_sh);

in gas/config/tc-sh.c:md_begin().

Cheers
        Nick