intel / media-driver

Intel Graphics Media Driver to support hardware decode, encode and video processing.
https://github.com/intel/media-driver/wiki
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[All] Using code lower scope micro-optimization #1877

Open GermanAizek opened 2 weeks ago

GermanAizek commented 2 weeks ago

In the case C++ compilers, it is better to reduce scope visibility as little as possible for better branching code generation, strict indication scope optimizes code guaranteed on all compilers.

Reference: https://stackoverflow.com/questions/26333583/c-c-compiler-optimization-regarding-variable-scope

Example:

clang-19 -O2 lower scope variables (3 pcs move instr)

изображение

clang-19 -O2 without PR changes (much more instr and CPU clock cycles)

изображение