错误:在操作数1处无效使用向量寄存器 [英] Error: invalid use of vector register at operand 1
问题描述
我正在64位Aarch64设备上的ARM环境下学习GCC内联汇编程序.我看到一条不太明白的错误消息.来自GCC内联汇编器的错误消息:
I'm learning GCC inline assembler under under ARM on a 64-bit Aarch64 device. I'm seeing an error message I don't quite understand. The error message in from GCC's inline assembler:
$ gcc -DNDEBUG -g3 -O1 -march=armv8-a+crc+crypto test.cc -o test.exe
/tmp/ccCHOWrn.s: Assembler messages:
/tmp/ccCHOWrn.s:19: Error: invalid use of vector register at operand 1 -- `pmull v0,v0,v0'
该示例程序只是尝试执行多项式乘法:
The sample program simply tries to exercise the polynomial multiply:
$ cat test.cc
#include <arm_neon.h>
int main(int argc, char* argv[])
{
uint64x2_t r = {0,0}, a = {2,4};
__asm__ __volatile__
(
"pmull %0, %1, %1;"
: "=w" (r)
: "w" (a), "w" (a)
: "cc"
);
return (int)r[0];
}
"w"是 Aarch64机器约束.在这种情况下，它描述为浮点或SIMD矢量寄存器" ，这似乎正是我想要的.
The "w" is an Aarch64 machine constraint. In this case, its described as "Floating point or SIMD vector register", which seems to be what I want.
uint64x2_t类型通常与ARM内部函数一起使用.但是它是一种128位的类型，并且已针对SIMD协处理器进行了对齐，因此对于该示例来说似乎是一个不错的选择.
The uint64x2_t type is typically used with ARM intrinsics. But its a 128-bit type and aligned for SIMD coprocessor, so it seemed like a good choice for the sample.
设备是 LeMaker HiKey ， Linaro映像和GCC 4.9.2编译器.看来此错误已在几年前修复，但我不确定是否与之相关: arm64上的fbb ftbfs .
The device is a LeMaker HiKey with a Linaro image and GCC 4.9.2 compiler. It looks like this bug was fixed a couple of years ago, but I'm not sure if its related: fbb ftbfs on arm64.
我有两个问题:
- 错误是什么意思，我该如何解决?
-
pmull和pmull2是否有内在函数?
- What does the error mean, and how can I fix it?
- Is there an intrinsic for
pmullandpmull2?
我尝试添加排列说明符，但是我不惊讶它不起作用，因为我不知道语法:
I tried adding the arrangement specifiers, but I'm not surprised it did not work since I don't know the syntax:
$ gcc -DNDEBUG -g3 -O1 -march=armv8-a+crc+crypto test.cc -o test.exe
test.cc: In function ‘int main(int, char**)’:
test.cc:8:15: error: expected ‘)’ before numeric constant
: "=w" (r.1q)
^
test.cc:8:15: error: expected ‘)’ before numeric constant
test.cc:9:6: error: expected ‘;’ before ‘:’ token
: "w" (a.1d), "w" (a.1d)
^
test.cc:9:6: error: expected primary-expression before ‘:’ token
我还尝试添加双百分号(即%%0和%%1)，因为汇编器在.att_stntax和.intel_syntax上遇到问题:
I also tried adding double percent signs (i.e., %%0 and %%1) since the assembler was having trouble with .att_stntax and .intel_syntax:
$ gcc -DNDEBUG -g3 -O1 -march=armv8-a+crc+crypto test.cc -o test.exe
/tmp/ccPpnvUP.s: Assembler messages:
/tmp/ccPpnvUP.s:19: Error: operand 1 should be a SIMD vector register -- `pmull %0,%1,%1'
推荐答案
错误是什么意思，我该如何解决?
What does the error mean, and how can I fix it?
我猜该错误意味着发生约束冲突.看起来下面的方法可以解决问题:
I guess the error means a constraint violation occurred. It looks like the following does the trick:
$ cat test.cc
#include <arm_neon.h>
#include <stdio.h>
int main(int argc, char* argv[])
{
uint64x2_t r = {0,0}, a = {2,4};
__asm__ __volatile__
(
"pmull %0.1q, %1.1d, %1.1d;"
: "=w" (r)
: "w" (a[0]), "w" (a[1])
: "cc"
);
fprintf(stdout, "%d, %d\n", r[0], r[1]);
return 0;
}
并且:
$ gcc -march=armv8-a+crc+crypto test.cc -o test.exe
$ ./test.exe
4, 0
并且:
$ gdb -batch -ex 'disassemble main' ./test.exe
Dump of assembler code for function main:
0x00000000004005f0 <+0>: stp x29, x30, [sp,#-64]!
0x00000000004005f4 <+4>: mov x29, sp
0x00000000004005f8 <+8>: str w0, [x29,#28]
0x00000000004005fc <+12>: str x1, [x29,#16]
0x0000000000400600 <+16>: movi v0.4s, #0x0
0x0000000000400604 <+20>: mov x0, v0.d[0]
0x0000000000400608 <+24>: mov x1, v0.d[1]
0x000000000040060c <+28>: fmov d0, x0
0x0000000000400610 <+32>: mov v0.d[1], x1
0x0000000000400614 <+36>: str q0, [x29,#48]
0x0000000000400618 <+40>: ldr q0, 0x4006a0
0x000000000040061c <+44>: mov x0, v0.d[0]
0x0000000000400620 <+48>: mov x1, v0.d[1]
0x0000000000400624 <+52>: fmov d0, x0
0x0000000000400628 <+56>: mov v0.d[1], x1
0x000000000040062c <+60>: str q0, [x29,#32]
0x0000000000400630 <+64>: ldr x0, [x29,#32]
0x0000000000400634 <+68>: ldr x1, [x29,#40]
0x0000000000400638 <+72>: fmov d0, x0
0x000000000040063c <+76>: fmov d1, x1
0x0000000000400640 <+80>: pmull v0.1q, v0.1d, v0.1d
0x0000000000400644 <+84>: mov x0, v0.d[0]
0x0000000000400648 <+88>: mov x1, v0.d[1]
0x000000000040064c <+92>: fmov d0, x0
0x0000000000400650 <+96>: mov v0.d[1], x1
0x0000000000400654 <+100>: str q0, [x29,#48]
0x0000000000400658 <+104>: adrp x0, 0x410000
0x000000000040065c <+108>: add x0, x0, #0x9f0
0x0000000000400660 <+112>: ldr x4, [x0]
0x0000000000400664 <+116>: ldr x1, [x29,#48]
0x0000000000400668 <+120>: ldr x2, [x29,#56]
0x000000000040066c <+124>: adrp x0, 0x400000
0x0000000000400670 <+128>: add x0, x0, #0x748
0x0000000000400674 <+132>: mov x3, x2
0x0000000000400678 <+136>: mov x2, x1
0x000000000040067c <+140>: mov x1, x0
0x0000000000400680 <+144>: mov x0, x4
0x0000000000400684 <+148>: bl 0x4004a0 <fprintf@plt>
0x0000000000400688 <+152>: mov w0, #0x0 // #0
0x000000000040068c <+156>: ldp x29, x30, [sp],#64
0x0000000000400690 <+160>: ret
End of assembler dump.
pmull和pmull2是否有内在函数?
Is there an intrinsic for pmull and pmull2?
似乎有一些内在函数:
$ gcc -march=armv8-a+crc+crypto -E test.cc | grep -B 4 pmull
__extension__ static __inline poly16x8_t __attribute__ ((__always_inline__))
vmull_high_p8 (poly8x16_t a, poly8x16_t b)
{
poly16x8_t result;
__asm__ ("pmull2 %0.8h,%1.16b,%2.16b"
--
__extension__ static __inline poly16x8_t __attribute__ ((__always_inline__))
vmull_p8 (poly8x8_t a, poly8x8_t b)
{
poly16x8_t result;
__asm__ ("pmull %0.8h, %1.8b, %2.8b"
--
static __inline poly128_t
vmull_p64 (poly64_t a, poly64_t b)
{
return
__builtin_aarch64_crypto_pmulldi_ppp (a, b);
--
static __inline poly128_t
vmull_high_p64 (poly64x2_t a, poly64x2_t b)
{
return __builtin_aarch64_crypto_pmullv2di_ppp (a, b);
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