Intel 64 and IA-32 Architectures Software Developers Manual Volume 1, Basic Architecture

Vol. 1 12-9
PROGRAMMING WITH SSE3 AND SUPPLEMENTAL SSE3
// if we get here, MONITOR/MWAIT is not available
MONITOR_MWAIT_works = FALSE;
}
12.4.3 Enable FTZ and DAZ for SIMD Floating-Point Computation
Enabling the FTZ and DAZ flags in the MXCSR register is likely to accelerate SIMD
floating-point computation where strict compliance to the IEEE standard 754-1985 is
not required. The FTZ flag is available to Intel 64 and IA-32 processors that support
the SSE; DAZ is available to Intel 64 processors and to most IA-32 processors that
support SSE/SSE2/SSE3.
Software can detect the presence of DAZ, modify the MXCSR register, and save and
restore state information by following the techniques discussed in Section 11.6.3
through Section 11.6.6.
12.4.4 Programming SSE3 with SSE/SSE2 Extensions
SIMD instructions in SSE3 extensions are intended to complement the use of
SSE/SSE2 in programming SIMD applications. Application software that intends to
use SSE3 instructions should also check for the availability of SSE/SSE2 instructions.
The FISTTP instruction in SSE3 is intended to accelerate x87 style programming
where performance is limited by frequent floating-point conversion to integers; this
happens when the x87 FPU control word is modified frequently. Use of FISTTP can
eliminate the need to access the x87 FPU control word.
12.5 OVERVIEW OF SSSE3 INSTRUCTIONS
SSSE3 provides 32 instructions to accelerate a variety of multimedia and signal
processing applications employing SIMD integer data. See:
• Section 12.6, “SSSE3 Instructions,” provides an introduction to individual SSE3
instructions.
• Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volumes
2A & 2B, provide detailed information on individual instructions.
• Chapter 12, “System Programming for Streaming SIMD Instruction Sets,” in the
Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A,
gives guidelines for integrating SSE/SSE2/SSE3/SSSE3 extensions into an
operating-system environment.