In Intel® processors, the flush-to-zero (FTZ) and denormals-are-zero (DAZ) flags in the MXCSR register are used to control floating-point calculations. Intel® Streaming SIMD Extensions (Intel® SSE) and Intel® Advanced Vector Extensions (Intel® AVX) instructions, including scalar and vector instructions, benefit from enabling the FTZ and DAZ flags. Floating-point computations using the Intel® SSE and Intel® AVX instructions are accelerated when the FTZ and DAZ flags are enabled. This improves the application's performance.
Manually set the flags with the following macros:
Feature |
Examples |
|---|---|
Enable FTZ |
_MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON) |
Enable DAZ |
_MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON) |
The prototypes for these macros are in xmmintrin.h (FTZ) and pmmintrin.h (DAZ).