"xcrun metal" vs. "MTLDevice::newLibraryWithSource()" compile options

Question

OctoBHVR OP

Created Jan ’24

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Hi,

when compiling shaders, metal command line tool has more options than MTLDevice::newLibraryWithSource().

For instance, "man metal" mentions 10 levels of optimization (-O0, -O1, -O2, -O3, -Ofast, -Os ...) while MTLCompileOptions doc only shows 2 levels (Default, Size).

Is there a way to pass -O2 as optimization level to MTLDevice::newLibraryWithSource()?

Thanks

Answered by Graphics and Games Engineer in 775924022

You do not need to explicitly set any MTLCompileOption to get -O2 optimization level as that is the default. The explicit level in the API is MTLLibraryOptimizationLevelDefault.

While man metal mentions all those options, please note that in the Metal Shading Language Specification 3.1 §1.5.5 (Optimization Compiler Options) lists -O2 and -Os (just like the documentation for MTLLibraryOptimizationLevel) as the only supported options.

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Answer 1

Graphics and Games Engineer OP

Apple

Jan ’24

Accepted Answer

You do not need to explicitly set any MTLCompileOption to get -O2 optimization level as that is the default. The explicit level in the API is MTLLibraryOptimizationLevelDefault.

While man metal mentions all those options, please note that in the Metal Shading Language Specification 3.1 §1.5.5 (Optimization Compiler Options) lists -O2 and -Os (just like the documentation for MTLLibraryOptimizationLevel) as the only supported options.

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