Clang集成汇编器和求反期间的“表达式中的未知令牌" [英] Clang integrated assembler and “unknown token in expression” during negate

问题描述

我们在默认配置中使用Clang.在默认配置中，使用的是Clang的集成汇编程序(而不是系统汇编程序，如GAS).我无法确定以下问题的确切问题(并解决):

We are using Clang in a default configuration. In the default configuration, Clang's Integrated Assembler is used (and not the system assembler, like GAS). I'm having trouble determining the exact problem (and fix) for:

make
...
clang++ -DNDEBUG -g2 -O3 -Wall -fPIC -arch i386 -arch x86_64 -pipe -Wno-tautological-compare -c integer.cpp
integer.cpp:542:2: error: unknown token in expression
        AS1(    neg             %1)
        ^
./cpu.h:220:17: note: expanded from macro 'AS1'
        #define AS1(x) GNU_AS1(x)
                       ^
./cpu.h:215:24: note: expanded from macro 'GNU_AS1'
        #define GNU_AS1(x) "\n\t" #x ";"
                              ^
<inline asm>:3:6: note: instantiated into assembly here
        neg %rcx;
            ^

有问题的代码在下面.

我 认为 ，以上错误可能与内联汇编和兼容性.一个简单的 negq％1 不能按预期工作:

I think the error above may be related to Inline Assembly and Compatibility. A simple negq %1 did not work as expected:

integer.cpp:543:2: error: unknown token in expression
        AS1(    negq    %1)
        ^
./cpu.h:220:17: note: expanded from macro 'AS1'
        #define AS1(x) GNU_AS1(x)
                       ^
./cpu.h:215:24: note: expanded from macro 'GNU_AS1'
        #define GNU_AS1(x) "\n\t" #x ";"
                              ^
<inline asm>:3:7: note: instantiated into assembly here
        negq %rcx;
             ^

自从其Intel大会以来，我还尝试了 negq [％1] ， neg DWORD PTR [％1] 和 negq DWORD PTR [％1] 不高兴.

Since its Intel assembly, I also tried negq [%1], neg DWORD PTR [%1] and negq DWORD PTR [%1] with no joy.

表达式中的未知标记"似乎是虚假消息，因为它抱怨的汇编指令似乎没有问题.因此，我怀疑Clang集成汇编程序还有其他令人反感的地方.

"unknown token in expression" appears to be a bogus message since the assembly instruction its complaining about does not seem to have a problem. So I suspect there is something else the Clang integrated assembler finds offensive.

代码有什么问题?

导致编译错误的代码:

int Baseline_Add(size_t N, word *C, const word *A, const word *B)
{
    word result;
    __asm__ __volatile__
    (
      ".intel_syntax;" "\n"
      AS1(  neg     %1)
      ASJ(  jz,     1, f)
      AS2(  mov     %0,[%3+8*%1])
      AS2(  add     %0,[%4+8*%1])
      AS2(  mov     [%2+8*%1],%0)
      ASL(0)
      AS2(  mov     %0,[%3+8*%1+8])
      AS2(  adc     %0,[%4+8*%1+8])
      AS2(  mov     [%2+8*%1+8],%0)
      AS2(  lea     %1,[%1+2])
      ASJ(  jrcxz,  1, f)
      AS2(  mov     %0,[%3+8*%1])
      AS2(  adc     %0,[%4+8*%1])
      AS2(  mov     [%2+8*%1],%0)
      ASJ(  jmp,    0, b)
      ASL(1)
      AS2(  mov     %0, 0)
      AS2(  adc     %0, %0)

      ".att_syntax;" "\n"
      : "=&r" (result), "+c" (N)
      : "r" (C+N), "r" (A+N), "r" (B+N)
      : "memory", "cc"
    );
    return (int)result;
}

推荐答案

这似乎是集成汇编程序中的一个问题.在CFE-dev邮件列表中询问该问题后，一位LLVM开发人员打开了PR.另请参见 LLVM错误24232-[X86]内联汇编操作数不适用于.intel_syntax .

This appears to be an issue in the Integrated Assembler. One of the LLVM developers opened a PR after the question was asked on the CFE-dev mailing list. Also see LLVM Bug 24232 - [X86] Inline assembly operands don't work with .intel_syntax.

我认为，这意味着如果我们有时间和精力来重写1000行的块，迈克尔的评论可能是一个解决方案.

I think that means Michael's comment could be a solution if we had the time and energy to rewrite blocks with 1000's of lines.

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