在linux中计算结果为非正规数时,刷新为零 [英] Flush to Zero when a computation results in a denormal number in linux
问题描述
您还没有指定架构 - 我会猜测这是一个相对较新的x86 [在这种情况下,您可以使用 _mm_getcsr
, _mm_setcsr
来操作SSE控制寄存器c $ c>< xmmintrin.h> (或< immintrin.h>
)标题。 b $ b
'flush-to-zero'位设置为0x8000,'denormals-are-zero'(对于输入/ src)设置为0x0040。
$ b $ < pmmintrin.h> (SSE3) _mm_setcsr(_mm_getcsr()| 0x8040) :
_mm_setcsr(_mm_getcsr()|(_MM_FLUSH_ZERO_ON | _MM_DENORMALS_ZERO_ON));
这可能会更容易确定下溢的源头,但不应将其视为解决方案,因为FP环境不再符合IEEE-754标准。
A computation in my C code is producing a gradual underflow, and when it happens the program is terminating with SIGFPE. How can I flush the result to zero when a gradual underflow (Denormal) results from a computation, and not terminate the execution? (I am working on a redhat linux machine). Thanks.
You haven't specified the architecture - I'm going to take a guess that it's a relatively recent x86[-64], in which case you can manipulate the SSE control register using _mm_getcsr
, _mm_setcsr
, specified in the <xmmintrin.h>
(or <immintrin.h>
) header.
The 'flush-to-zero' bit is set with 0x8000, and 'denormals-are-zero' (for inputs / src) is set with 0x0040.
_mm_setcsr(_mm_getcsr() | 0x8040);
or with <pmmintrin.h>
(SSE3) :
_mm_setcsr(_mm_getcsr() | (_MM_FLUSH_ZERO_ON | _MM_DENORMALS_ZERO_ON));
This might make it easier to determine the source of the underflow, but it shouldn't be considered a solution, since the FP environment is no longer IEEE-754 compliant.
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