x, Qx

Tells the compiler to generate optimized code specialized for the Intel processor that executes your program.

IDE Equivalent

Windows: Code Generation > Intel Processor-Specific Optimization

Linux: Code Generation > Intel Processor-Specific Optimization

Mac OS X: Code Generation > Intel Processor-Specific Optimization

Architectures

IA-32, Intel® 64 architectures

Syntax

Linux and Mac OS X:

-xprocessor

Windows:

/Qxprocessor

Arguments

processor

Indicates the processor for which code is generated. Many of the following descriptions refer to Intel® Streaming SIMD Extensions (Intel® SSE) and Supplemental Streaming SIMD Extensions (Intel® SSSE). Possible values are:

Host	Can generate instructions for the highest instruction set available on the compilation host processor. On Intel processors, this may correspond to the most suitable –x (Linux* and Mac OS* X) or /Qx (Windows*) option. On non-Intel processors, this may correspond to the most suitable –m (Linux and Mac OS X) or /arch (Windows) option. The resulting executable may not run on a processor different from the host in the following cases: If the processor does not support all of the instructions supported by the host processor. If the host is an Intel processor and the other processor is a non-Intel processor.
AVX	Optimizes for Intel processors that support Intel® Advanced Vector Extensions (Intel® AVX).
SSE4.2	Can generate Intel® SSE4 Efficient Accelerated String and Text Processing instructions supported by Intel® Core™ i7 processors. Can generate Intel® SSE4 Vectorizing Compiler and Media Accelerator, Intel® SSSE3, SSE3, SSE2, and SSE instructions and it can optimize for the Intel® Core™ processor family.
SSE4.1	Can generate Intel® SSE4 Vectorizing Compiler and Media Accelerator instructions for Intel processors. Can generate Intel® SSSE3, SSE3, SSE2, and SSE instructions and it can optimize for Intel® 45nm Hi-k next generation Intel® Core™ microarchitecture. This replaces value S, which is deprecated.
SSE3_ATOM	Optimizes for the Intel® Atom™ processor and Intel® Centrino® Atom™ Processor Technology. Can generate MOVBE instructions, depending on the setting of option -minstruction (Linux and Mac OS) or /Qinstruction (Windows).
SSSE3	Can generate Intel® SSSE3, SSE3, SSE2, and SSE instructions for Intel processors and it can optimize for the Intel® Core™2 Duo processor family. For Mac OS* X systems, this value is only supported on Intel® 64 architecture. This replaces value T, which is deprecated.
SSE3	Can generate Intel® SSE3, SSE2, and SSE instructions for Intel processors and it can optimize for processors based on Intel® Core™ microarchitecture and Intel NetBurst® microarchitecture. For Mac OS* X systems, this value is only supported on IA-32 architecture.This replaces value P, which is deprecated.
SSE2	Can generate Intel® SSE2 and SSE instructions for Intel processors, and it can optimize for Intel® Pentium® 4 processors, Intel® Pentium® M processors, and Intel® Xeon® processors with Intel® SSE2. This value is not available on Mac OS* X systems. This replaces value N, which is deprecated.

Default

Windows* systems: None
Linux* systems: None
Mac OS* X systems using IA-32 architecture: SSE3
Mac OS* X systems using Intel® 64 architecture: SSSE3

On Windows systems, if neither /Qx nor /arch is specified, the default is /arch:SSE2.

On Linux systems, if neither -x nor -m is specified, the default is -msse2.

Description

This option tells the compiler to generate optimized code specialized for the Intel processor that executes your program. It also enables optimizations in addition to Intel processor-specific optimizations. The specialized code generated by this option may run only on a subset of Intel processors.

This option can enable optimizations depending on the argument specified. For example, it may enable Intel® Streaming SIMD Extensions 4 (Intel® SSE4), Intel® Supplemental Streaming SIMD Extensions 3 (Intel® SSSE3), Intel® Streaming SIMD Extensions 3 (Intel® SSE3), Intel® Streaming SIMD Extensions 2 (Intel® SSE2), or Intel® Streaming SIMD Extensions (Intel® SSE) instructions.

The binaries produced by these values will run on Intel processors that support all of the features for the targeted processor. For example, binaries produced with SSE3 will run on an Intel® Core™ 2 Duo processor, because that processor completely supports all of the capabilities of the Intel® Pentium® 4 processor, which the SSE3 value targets. Specifying the SSSE3 value has the potential of using more features and optimizations available to the Intel® Core™ 2 Duo processor.

Do not use processor values to create binaries that will execute on a processor that is not compatible with the targeted processor. The resulting program may fail with an illegal instruction exception or display other unexpected behavior. For example, binaries produced with SSE3 may produce code that will not run on Intel® Pentium® III processors or earlier processors that do not support SSE3 instructions.

Compiling the function main() with any of the processor values produces binaries that display a fatal run-time error if they are executed on unsupported processors. For more information, see Optimizing Applications.

If you specify more than one processor value, code is generated for only the highest-performing processor specified. The highest-performing to lowest-performing processor values are: SSE4.2, SSE4.1, SSSE3, SSE3, SSE2. Note that processor values AVX and SSE3_ATOM do not fit within this group.

Compiler options m and arch produce binaries that should run on processors not made by Intel that implement the same capabilities as the corresponding Intel processors.

Previous value O is deprecated and has been replaced by option -msse3 (Linux and Mac OS X) and option /arch:SSE3 (Windows).

Previous values W and K are deprecated. The details on replacements are as follows:

Mac OS X systems: On these systems, there is no exact replacement for W or K. You can upgrade to the default option -msse3 (IA-32 architecture) or option -mssse3 (Intel® 64 architecture).
Windows and Linux systems: The replacement for W is -msse2 (Linux) or /arch:SSE2 (Windows). There is no exact replacement for K. However, on Windows systems, /QxK is interpreted as /arch:IA32; on Linux systems, -xK is interpreted as -mia32. You can also do one of the following:
- Upgrade to option -msse2 (Linux) or option /arch:SSE2 (Windows). This will produce one code path that is specialized for Intel® SSE2. It will not run on earlier processors
- Specify the two option combination -mia32 -axSSE2 (Linux) or /arch:IA32 /QaxSSE2 (Windows). This combination will produce an executable that runs on any processor with IA-32 architecture but with an additional specialized Intel® SSE2 code path.

The -x and /Qx options enable additional optimizations not enabled with option -m or option /arch.

On Windows* systems, options /Qx and /arch are mutually exclusive. If both are specified, the compiler uses the last one specified and generates a warning. Similarly, on Linux* and Mac OS* X systems, options -x and -m are mutually exclusive. If both are specified, the compiler uses the last one specified and generates a warning.

Alternate Options

None