vec-threshold, Qvec-threshold
Sets a threshold for the vectorization of
loops.
Syntax
Linux:
-vec-threshold
[
n
]
Windows:
/Qvec-threshold
[[
:]
n
]
Arguments
- n
- Is an integer whose value is the threshold for the vectorization of loops. Possible values are 0 through 100.Ifnis 0, loops get vectorized always, regardless of computation work volume.Ifnis 100, loops get vectorized when performance gains are predicted based on the compiler analysis data. Loops get vectorized only if profitable vector-level parallel execution is almost certain.The intermediate 1 to 99 values represent the percentage probability for profitable speed-up. For example,n=50 directs the compiler to vectorize only if there is a 50% probability of the code speeding up if executed in vector form.
Default
- -vec-threshold100or/Qvec-threshold100
- Loops get vectorized only if profitable vector-level parallel execution is almost certain. This is also the default if you do not specifyn.
Description
This option sets a threshold for the vectorization of
loops based on the probability of profitable execution of the vectorized loop
in parallel.
This option is useful for loops whose computation work
volume cannot be determined at compile-time. The threshold is usually relevant
when the loop trip count is unknown at compile-time.
The compiler applies a heuristic that tries to balance
the overhead of creating multiple threads versus the amount of work available
to be shared amongst the threads.
This option only applies to host compilation. When
offloading is enabled, it does not impact device-specific compilation.
IDE Equivalent
Visual Studio:
Optimization > Threshold
For Vectorization
Eclipse:
Optimization > Enable Maximum Vector-level
Parallelism
Xcode:
Optimization > Enable Maximum Vector-level Parallelism
Alternate Options
None