Automatically generate xmm register name in gas macro?

Question

I would like to write a gas macro to generate code containing various movdqu commands in the xmm register depending on the parameter n.

.macro xxmov n, p1 .if (\n == 1) xor %eax, %eax .endif .if (\n - 1) xxmov (\n - 1), \p1 .endif movdqu ((\n - 1)*0x10)(\p1), %xmm0 .endm xxmov 14, %rsi 

After compiling the disassembled code,

  0000000000000000 <.text>: 0: 31 c0 xor %eax,%eax 2: f3 0f 6f 06 movdqu (%rsi),%xmm0 6: f3 0f 6f 46 10 movdqu 0x10(%rsi),%xmm0 b: f3 0f 6f 46 20 movdqu 0x20(%rsi),%xmm0 10: f3 0f 6f 46 30 movdqu 0x30(%rsi),%xmm0 15: f3 0f 6f 46 40 movdqu 0x40(%rsi),%xmm0 1a: f3 0f 6f 46 50 movdqu 0x50(%rsi),%xmm0 1f: f3 0f 6f 46 60 movdqu 0x60(%rsi),%xmm0 24: f3 0f 6f 46 70 movdqu 0x70(%rsi),%xmm0 29: f3 0f 6f 86 80 00 00 movdqu 0x80(%rsi),%xmm0 30: 00 31: f3 0f 6f 86 90 00 00 movdqu 0x90(%rsi),%xmm0 38: 00 39: f3 0f 6f 86 a0 00 00 movdqu 0xa0(%rsi),%xmm0 40: 00 41: f3 0f 6f 86 b0 00 00 movdqu 0xb0(%rsi),%xmm0 48: 00 49: f3 0f 6f 86 c0 00 00 movdqu 0xc0(%rsi),%xmm0 50: 00 51: f3 0f 6f 86 d0 00 00 movdqu 0xd0(%rsi),%xmm0 58: 00 

However, when I replaced% xmm0 with% xmm \ n in the above xxmov macro, I got a compilation error,

  $ gcc -c mac.s mac.s: Assembler messages: mac.s:17: Error: bad register name `%xmm(((((((((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm((((((((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm(((((((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm((((((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm(((((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm((((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm(((((((14 - 1)- 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm((((((14 - 1)- 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm(((((14 - 1)- 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm((((14 - 1)- 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm(((14 - 1)- 1)- 1)' mac.s:17: Error: bad register name `%xmm((14 - 1)- 1)' mac.s:17: Error: bad register name `%xmm(14 - 1)' 

So, is it anyway, can I manipulate my macro with the registration name xmm (from% xmm0 to% xmm_ {n-1})? I tried the \ @ (% xmm \ @) mentioned in http://sourceware.org/binutils/docs/as/Macro.html#Macro . However, this is not very good, because I would like to use this macro several times, while \ @ seems to grow monotonously.

Answer 1

How about, not counting, do you keep the variable counting? Like this:

 .macro xxmov n, p1, cnt=0 .if (\cnt == 0) xor %eax, %eax .endif .if (\cnt != \n) movdqu \@*0x10(\p1), %xmm\@ xxmov \n, \p1, (\cnt + 1) .endif .endm xxmov 14, %rsi 

What generates:

 0000000000000000 <.text>: 0: 31 c0 xor %eax,%eax 2: f3 0f 6f 06 movdqu (%rsi),%xmm0 6: f3 0f 6f 4e 10 movdqu 0x10(%rsi),%xmm1 b: f3 0f 6f 56 20 movdqu 0x20(%rsi),%xmm2 10: f3 0f 6f 5e 30 movdqu 0x30(%rsi),%xmm3 15: f3 0f 6f 66 40 movdqu 0x40(%rsi),%xmm4 1a: f3 0f 6f 6e 50 movdqu 0x50(%rsi),%xmm5 1f: f3 0f 6f 76 60 movdqu 0x60(%rsi),%xmm6 24: f3 0f 6f 7e 70 movdqu 0x70(%rsi),%xmm7 29: f3 44 0f 6f 86 80 00 00 00 movdqu 0x80(%rsi),%xmm8 32: f3 44 0f 6f 8e 90 00 00 00 movdqu 0x90(%rsi),%xmm9 3b: f3 44 0f 6f 96 a0 00 00 00 movdqu 0xa0(%rsi),%xmm10 44: f3 44 0f 6f 9e b0 00 00 00 movdqu 0xb0(%rsi),%xmm11 4d: f3 44 0f 6f a6 c0 00 00 00 movdqu 0xc0(%rsi),%xmm12 56: f3 44 0f 6f ae d0 00 00 00 movdqu 0xd0(%rsi),%xmm13 

Update: Unfortunately, this only works for using the first macro in the file. If you need to use it more than once in a single file, it seems that using the .altmacro syntax is the way to go (you can disable it again with .noaltmacro ):

 .altmacro .macro xxmov n, p .if (\n == 1) xor %eax, %eax .endif .if (\n > 1) xxmov %(\n - 1), \p .endif movdqu (\n - 1)*0x10 (%\p) , %xmm\n .endm xxmov 4, rsi xxmov 14, rsi