Hi Nathan,
Thanks for your guide. When I debugged the exe file or make it ran on
8548 board, the vmhaddshs makes the exe file hang out. Could I compile
the source for 8540 (e500v1 instructions) only?
Thanks for your help,
Ha Luong
On Tue, Dec 16, 2008 at 9:45 PM, Nathan Froyd <froy...@codesourcery.com> wrote:
> On Tue, Dec 16, 2008 at 12:28:10PM +0700, Ha Luong wrote:
>> I used gcc-4.3.2 to compile the c source(*) and it generated
>> "vmhraddshs" instruction when I compiled with -mcpu=8540.
>> 000103A4: 11EB0321 vmhraddshs vr15,vr11,vr0,vr12
>
> You are running into the problem that the Altivec and SPE opcode spaces
> overlap, so the instructions that you see generated depend on what
> disassembler you use. For example, compiling the assembler file test.s:
>
> .text
> .long 0x10074B20
> .long 0x11eb0321
>
> with:
>
> powerpc-linux-gnu-gcc -c -o test.o test.s
>
> and disassembling:
>
> powerpc-linux-gnu-objdump -d test.o
>
> gives you:
>
> Disassembly of section .text:
>
> 00000000 <.text>:
> 0: 10 07 4b 20 vmhaddshs v0,v7,v9,v12
> 4: 11 eb 03 21 vmhraddshs v15,v11,v0,v12
>
> but if you tell objdump to disassemble e500 instructions instead (use -M
> e500x2 to include e500v2 instructions):
>
> powerpc-linux-gnu-objdump -d -M e500 test.o
>
> you see:
>
> Disassembly of section .text:
>
> 00000000 <.text>:
> 0: 10 07 4b 20 evstddx r0,r7,r9
> 4: 11 eb 03 21 evstdd r15,0(r11)
>
> The compiler is generating evstdd{,x} instructions, not vmhraddshs
> instructions.
>
> -Nathan
>
