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Re: ldreqd instruction in arm version 4?
- From: Arvind Krishnaswamy <arvind at CS dot Arizona dot EDU>
- To: Alan Lehotsky <apl at alum dot mit dot edu>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Thu, 24 Jan 2002 19:13:20 -0700 (MST)
- Subject: Re: ldreqd instruction in arm version 4?
The ARM Architecture Reference Manual lists the ldrd/strd instructions as
part of the dsp enhanced instruction set
available in arm architecture versions 5 and above. Hence an explicit
switch of -march=armv4t shouldn't generate these instructions. Is there some way
by which (other than -march) that I can use to generate arm version 4T
instructions?
-Arvind
On Thu, 24 Jan 2002, Alan Lehotsky wrote:
> ldr<cond>d and str<cond>d are specific to Intel's ARM processor (think that documentation is available at Intel.com on this
> (and probably also at the ARM web site...).
>
> ldrd/strd use an even/odd register pair and an 8-byte aligned memory address to transfer 8 bytes of data.
> It's faster than ldm/stm....
>
>
>
> At 3:12 PM -0700 1/24/02, Arvind Krishnaswamy wrote:
>
> >Hi,
> >I used the -march=armv4t with both the arm-elf-gcc compiler and xscale-elf-gcc
> >compiler. But xscale-elf-gcc generates different code. The ldreqd instruction
> >is used code generated by xscale-elf-gcc bt is absent in code generated by
> >arm-elf-gcc. Doesn't -march=armv4t specify the instruction to be used? I also
> >checked the arm architecture reference manual for this instruction but the
> >opcode for this instruction does not match any ldr instructions there.
> >What am I missing?
> >
> >-Arvind
>
>