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// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// 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.
package goexperiment
//go:generate go run mkconsts.go
// 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".
type Flags struct {
FieldTrack bool
PreemptibleLoops bool
StaticLockRanking bool
// Regabi is split into several sub-experiments that can be
// enabled individually. Not all combinations work.
// The "regabi" GOEXPERIMENT is an alias for all "working"
// subexperiments.
// 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