qopt-streaming-stores, Qopt-streaming-stores

Intel® C++ Compiler Classic Developer Guide and Reference

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ID 767249

Date 12/16/2022

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Public

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qopt-streaming-stores, Qopt-streaming-stores

Enables generation of streaming stores for optimization.

Syntax

Linux and macOS:

-qopt-streaming-stores=keyword

-qno-opt-streaming-stores

Windows:

/Qopt-streaming-stores:keyword

/Qopt-streaming-stores-

Arguments

keyword

Specifies whether streaming stores are generated. Possible values are:

always

Enables generation of streaming stores for optimization. The compiler optimizes under the assumption that the application is memory bound.

When this option setting is specified, it is your responsibility to also insert any fences as required to ensure correct memory ordering within a thread or across threads. One typical way to do this is to insert a _mm_sfence() intrinsic call just after the loops (such as the initialization loop) where the compiler may insert streaming store instructions.

never

Disables generation of streaming stores for optimization. Normal stores are performed. This is the same as specifying -qno-opt-streaming-stores (Linux*) or /Qopt-streaming-stores- (Windows*).

auto

Lets the compiler decide which instructions to use.

Default

-qopt-streaming-stores=auto
or /Qopt-streaming-stores:auto

The compiler decides whether to use streaming stores or normal stores.

Description

This option enables generation of streaming stores for optimization. This method stores data with instructions that use a non-temporal buffer, which minimizes memory hierarchy pollution.

This option may be useful for applications that can benefit from streaming stores.

IDE EquivalentNone

Alternate Options

None

Example

The following example shows a way to insert fences when specifying -qopt-streaming-stores=always or /Qopt-streaming-stores:always:

void simple1(double * restrict a, double * restrict b, double * restrict c, double *d, int n)
{
    int i, j;

#pragma omp parallel for
      for (j=0; j<n; j++) {
        a[j] = 1.0;
        b[j] = 2.0;
        c[j] = 0.0;
        }

      _mm_sfence(); // OR _mm_mfence();

#pragma omp parallel for
    for (i=0; i<n; i++)
        a[i] = a[i] + c[i]*b[i];
}

Parent topic: Advanced Optimization Options

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qopt-streaming-stores, Qopt-streaming-stores

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