Intel-Specific Pragma Reference

Intel® C++ Compiler Classic Developer Guide and Reference

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ID 767249

Date 3/31/2023

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Intel-Specific Pragma Reference

Pragmas specific to the Intel® C++ Compiler Classic are listed in the following table.

Some pragmas are available for both Intel® microprocessors and non-Intel microprocessors, but may perform additional optimizations for Intel® microprocessors than for non-Intel microprocessors.

Pragma	Description
alloc_section	Allocates one or more variables in the specified section. Controls section attribute specification for variables.
block_loop/noblock_loop	Enables or disables loop blocking for the immediately following nested loops. block_loop enables loop blocking for the nested loops. noblock_loop disables loop blocking for the nested loops.
code_align	Specifies the byte alignment for a loop
distribute_point	Instructs the compiler to prefer loop distribution at the location indicated.
inline/noinline/forceinline	Specifies inlining of all calls in a statement. This also describes pragmas forceinline and noinline.
intel omp task	For Intel legacy tasking, specifies a unit of work, potentially executed by a different thread.
intel omp taskq	For Intel legacy tasking, specifies an environment for the while loop in which to queue the units of work specified by the enclosed `task` pragma.
ivdep	Instructs the compiler to ignore assumed vector dependencies.
loop_count	Specifies the iterations for a for loop.
nofusion	Prevents a loop from fusing with adjacent loops.
novector	Specifies that a particular loop should never be vectorized.
omp simd early_exit	Extends #pragma omp simd, allowing vectorization of multiple exit loops.
optimization_level	Controls optimization for one function or all functions after its first occurrence.
optimization_parameter	Passes certain information about a function to the optimizer.
optimize	Enables or disables optimizations for code after this pragma until another optimize pragma or end of the translation unit.
parallel/noparallel	Resolves dependencies to facilitate auto-parallelization of the immediately following loop (parallel) or prevents auto-parallelization of the immediately following loop (noparallel).
prefetch/noprefetch	Invites the compiler to issue or disable requests to prefetch data from memory. This pragma applies only to Intel® Advanced Vector Extensions 512 (Intel® AVX-512).
simd	Enforces vectorization of loops.
simdoff	Specifies a block of code in the SIMD loop or SIMD-enabled function that should be executed serially, in a logical order of SIMD lanes.
unroll/nounroll	Tells the compiler to unroll or not to unroll a counted loop.
unroll_and_jam/nounroll_and_jam	Enables or disables loop unrolling and jamming. These pragmas can only be applied to iterative for loops.
unused	Describes variables that are unused (warnings not generated).
vector	Tells the compiler that the loop should be vectorized according to the argument keywords.

Parent topic: Pragmas

alloc_section
Allocates one or more variables in the specified section. Controls section attribute specification for variables.
block_loop/noblock_loop
Enables or disables loop blocking for the immediately following nested loops. block_loop enables loop blocking for the nested loops. noblock_loop disables loop blocking for the nested loops.
code_align
Specifies the byte alignment for a loop
distribute_point
Instructs the compiler to prefer loop distribution at the location indicated.
inline, noinline, forceinline
Specifies inlining of all calls in a statement. This also describes pragmas forceinline and noinline.
intel omp task
For Intel legacy tasking, specifies a unit of work, potentially executed by a different thread.
intel omp taskq
For Intel legacy tasking, specifies an environment for the while loop in which to queue the units of work specified by the enclosed task pragma.
ivdep
Instructs the compiler to ignore assumed vector dependencies.
loop_count
Specifies the iterations for a for loop.
nofusion
Prevents a loop from fusing with adjacent loops.
novector
Specifies that a particular loop should never be vectorized.
omp simd early_exit
Extends #pragma omp simd, allowing vectorization of multiple exit loops.
optimize
Enables or disables optimizations for code after this pragma until another optimize pragma or end of the translation unit.
optimization_level
Controls optimization for one function or all functions after its first occurrence.
optimization_parameter
Passes certain information about a function to the optimizer.
parallel/noparallel
Resolves dependencies to facilitate auto-parallelization of the immediately following loop (parallel) or prevents auto-parallelization of the immediately following loop (noparallel).
prefetch/noprefetch
Invites the compiler to issue or disable requests to prefetch data from memory. This pragma applies only to Intel® Advanced Vector Extensions 512 (Intel® AVX-512).
simd
Enforces vectorization of loops.
simdoff
Specifies a block of code in the SIMD loop or SIMD-enabled function that should be executed serially, in a logical order of SIMD lanes.
unroll/nounroll
Tells the compiler to unroll or not to unroll a counted loop.
unroll_and_jam/nounroll_and_jam
Enables or disables loop unrolling and jamming. These pragmas can only be applied to iterative for loops.
unused
Describes variables that are unused (warnings not generated).
vector
Tells the compiler that the loop should be vectorized according to the argument keywords.

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