_MM_TRANSPOSE4_PS会导致GCC中的编译器错误？ [英] _MM_TRANSPOSE4_PS causes compiler errors in GCC?

问题描述

我第一次编译我的数学库在GCC而不是MSVC，并通过所有的小错误，我打了一个根本没有意义：

行284：错误：作为赋值的左操作数需要lvalue

this：

_MM_TRANSPOSE4_PS（r，u，t，_mm_setr_ps（0.0f，0.0f，0.0f，1.0f））; c $ c>

（r，u和t都是 __ m128 的实例）

熟悉 xmmintrin.h 的用户将会注意到 _MM_TRANSPOSE4_PS isn' t实际上是一个函数，而是一个宏，扩展为：

  / *转置由行[0- 3]。 * / 
 #define _MM_TRANSPOSE4_PS（row0，row1，row2，row3）\ 
 do {\ 
 __v4sf __r0 =（row0），__r1 =（row1），__r2 = ，__r3 =（row3）; \ 
 __v4sf __t0 = __builtin_ia32_unpcklps（__r0，__r1）; \ 
 __v4sf __t1 = __builtin_ia32_unpcklps（__r2，__r3）; \ 
 __v4sf __t2 = __builtin_ia32_unpckhps（__r0，__r1）; \ 
 __v4sf __t3 = __builtin_ia32_unpckhps（__r2，__r3）; \ 
（row0）= __builtin_ia32_movlhps（__t0，__t1）; \ 
（row1）= __builtin_ia32_movhlps（__t1，__t0）; \ 
（row2）= __builtin_ia32_movlhps（__t2，__t3）; \ 
（row3）= __builtin_ia32_movhlps（__t3，__t2）; \ 
} while（0）
  

那么...是什么原因导致我的编译器错误？我不在这里重新定义任何东西，我知道。

解决方案

您需要更改：

  _MM_TRANSPOSE4_PS（r，u，t，_mm_setr_ps（0.0f，0.0f，0.0f，1.0f））; 
  

到：

 code> __ m128 v = _mm_setr_ps（0.0f，0.0f，0.0f，1.0f）; 
 _MM_TRANSPOSE4_PS（r，u，t，v）; 
  

，因为这是一个就地转置，并且4个输入向量也用于输出。 / p>

I'm compiling my math library in GCC instead of MSVC for the first time and going through all the little errors, and I've hit one that simply makes no sense:

Line 284: error: lvalue required as left operand of assignment

What's on line 284? this:

_MM_TRANSPOSE4_PS(r, u, t, _mm_setr_ps(0.0f, 0.0f, 0.0f, 1.0f));

(r, u, and t are all instances of __m128)

Those familiar with using xmmintrin.h will be aware that _MM_TRANSPOSE4_PS isn't actually a function, but rather a macro, which expands to:

/* Transpose the 4x4 matrix composed of row[0-3].  */
#define _MM_TRANSPOSE4_PS(row0, row1, row2, row3)           \
do {                                    \
  __v4sf __r0 = (row0), __r1 = (row1), __r2 = (row2), __r3 = (row3);    \
  __v4sf __t0 = __builtin_ia32_unpcklps (__r0, __r1);           \
  __v4sf __t1 = __builtin_ia32_unpcklps (__r2, __r3);           \
  __v4sf __t2 = __builtin_ia32_unpckhps (__r0, __r1);           \
  __v4sf __t3 = __builtin_ia32_unpckhps (__r2, __r3);           \
  (row0) = __builtin_ia32_movlhps (__t0, __t1);             \
  (row1) = __builtin_ia32_movhlps (__t1, __t0);             \
  (row2) = __builtin_ia32_movlhps (__t2, __t3);             \
  (row3) = __builtin_ia32_movhlps (__t3, __t2);             \
} while (0)

So... what's causing my compiler errors? I don't redefine anything here, that I know of. This exact same code compiled and ran perfectly well when I was using MSVC.

解决方案

You need to change:

_MM_TRANSPOSE4_PS(r, u, t, _mm_setr_ps(0.0f, 0.0f, 0.0f, 1.0f));

to:

__m128 v = _mm_setr_ps(0.0f, 0.0f, 0.0f, 1.0f);
_MM_TRANSPOSE4_PS(r, u, t, v);

since this is an in-place transpose, and the 4 input vectors are also used for output.

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