package goexperiment

import "internal/goexperiment"

Package goexperiment implements support for toolchain experiments.

Toolchain experiments are controlled by the GOEXPERIMENT environment variable. GOEXPERIMENT is a comma-separated list of experiment names. GOEXPERIMENT can be set at make.bash time, which sets the default experiments for binaries built with the tool chain; or it can be set at build time. GOEXPERIMENT can also be set to "none", which disables any experiments that were enabled at make.bash time.

Experiments are exposed to the build in the following ways:

- Build tag goexperiment.x is set if experiment x (lower case) is enabled.

- For each experiment x (in camel case), this package contains a boolean constant x and an integer constant xInt.

- In runtime assembly, the macro GOEXPERIMENT_x is defined if experiment x (lower case) is enabled.

In the toolchain, the set of experiments enabled for the current build should be accessed via objabi.Experiment.

The set of experiments is included in the output of runtime.Version() and "go version <binary>" if it differs from the default experiments.

For the set of experiments supported by the current toolchain, see "go doc goexperiment.Flags".

Note that this package defines the set of experiments (in Flags) and records the experiments that were enabled when the package was compiled (as boolean and integer constants).

Note especially that this package does not itself change behavior at run time based on the GOEXPERIMENT variable. The code used in builds to interpret the GOEXPERIMENT variable is in the separate package internal/buildcfg.

Index ¶

• Constants
• type Flags

Constants ¶

const FieldTrack = false

const FieldTrackInt = 0

const PreemptibleLoops = false

const PreemptibleLoopsInt = 0

const Regabi = false

const RegabiArgs = false

const RegabiArgsInt = 0

const RegabiDefer = false

const RegabiDeferInt = 0

const RegabiG = false

const RegabiGInt = 0

const RegabiInt = 0

const RegabiReflect = false

const RegabiReflectInt = 0

const RegabiWrappers = false

const RegabiWrappersInt = 0

const StaticLockRanking = false

const StaticLockRankingInt = 0

Types ¶

type Flags ¶

type Flags struct {
	FieldTrack        bool
	PreemptibleLoops  bool
	StaticLockRanking bool

	// RegabiWrappers enables ABI wrappers for calling between
	// ABI0 and ABIInternal functions. Without this, the ABIs are
	// assumed to be identical so cross-ABI calls are direct.
	RegabiWrappers bool
	// RegabiG enables dedicated G and zero registers in
	// ABIInternal.
	//
	// Requires wrappers because it makes the ABIs incompatible.
	RegabiG bool
	// RegabiReflect enables the register-passing paths in
	// reflection calls. This is also gated by intArgRegs in
	// reflect and runtime (which are disabled by default) so it
	// can be used in targeted tests.
	RegabiReflect bool
	// RegabiDefer enables desugaring defer and go calls
	// into argument-less closures.
	RegabiDefer bool
	// RegabiArgs enables register arguments/results in all
	// compiled Go functions.
	//
	// Requires wrappers (to do ABI translation), g (because
	// runtime assembly that's been ported to ABIInternal uses the
	// G register), reflect (so reflection calls use registers),
	// and defer (because the runtime doesn't support passing
	// register arguments to defer/go).
	RegabiArgs bool
}

Flags is the set of experiments that can be enabled or disabled in the current toolchain.

When specified in the GOEXPERIMENT environment variable or as build tags, experiments use the strings.ToLower of their field name.

For the baseline experimental configuration, see objabi.experimentBaseline.

If you change this struct definition, run "go generate".

Source Files ¶

exp_fieldtrack_off.go exp_preemptibleloops_off.go exp_regabi_off.go exp_regabiargs_off.go exp_regabidefer_off.go exp_regabig_off.go exp_regabireflect_off.go exp_regabiwrappers_off.go exp_staticlockranking_off.go flags.go