Restructure code to let linker perform deadcode elimination step #1956
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This PR exceeds the recommended size of 200 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size. |
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The CLA thing isn't working for some reason. |
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This PR exceeds the recommended size of 200 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size. |
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Thanks @aarzilli ! |
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Unless I made a mistake there shouldn't be any behavior changes (as in, observable from the outside). Happy to explain anything about this if needed. |
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Ping? |
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This PR exceeds the recommended size of 200 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size. |
Cobra, in its default configuration, will execute a template to generate help, usage and version outputs. Text/template execution calls MethodByName and MethodByName disables dead code elimination in the Go linker, therefore all programs that make use of cobra will be linked with dead code elimination disabled, even if they end up replacing the default usage, help and version formatters with a custom function and no actual text/template evaluations are ever made at runtime. Dead code elimination in the linker helps reduce disk space and memory utilization of programs. For example, for the simple example program used by TestDeadcodeElimination 40% of the final executable size is dead code. For a more realistic example, 12% of the size of Delve's executable is deadcode. This PR changes Cobra so that, in its default configuration, it does not automatically inhibit deadcode elimination by: 1. changing Cobra's default behavior to emit output for usage and help using simple Go functions instead of template execution 2. quarantining all calls to template execution into SetUsageTemplate, SetHelpTemplate and SetVersionTemplate so that the linker can statically determine if they are reachable
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This PR exceeds the recommended size of 200 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size. |
Cobra, in its default configuration, will execute a template to generate help, usage and version outputs. Text/template execution calls MethodByName and MethodByName disables dead code elimination in the Go linker, therefore all programs that make use of cobra will be linked with dead code elimination disabled, even if they end up replacing the default usage, help and version formatters with a custom function and no actual text/template evaluations are ever made at runtime.
Dead code elimination in the linker helps reduce disk space and memory utilization of programs. For example, for the simple example program used by TestDeadcodeElimination 40% of the final executable size is dead code. For a more realistic example, 12% of the size of Delve's executable is deadcode.
This PR changes Cobra so that, in its default configuration, it does not automatically inhibit deadcode elimination by: