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Diffstat (limited to 'src/internal/goexperiment/flags.go')
| -rw-r--r-- | src/internal/goexperiment/flags.go | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/src/internal/goexperiment/flags.go b/src/internal/goexperiment/flags.go new file mode 100644 index 0000000..dacc4c3 --- /dev/null +++ b/src/internal/goexperiment/flags.go @@ -0,0 +1,130 @@ +// 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 + BoringCrypto 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 + // RegabiArgs enables register arguments/results in all + // compiled Go functions. + // + // Requires wrappers (to do ABI translation), and reflect (so + // reflection calls use registers). + RegabiArgs bool + + // HeapMinimum512KiB reduces the minimum heap size to 512 KiB. + // + // This was originally reduced as part of PacerRedesign, but + // has been broken out to its own experiment that is disabled + // by default. + HeapMinimum512KiB bool + + // CoverageRedesign enables the new compiler-based code coverage + // tooling. + CoverageRedesign bool + + // Arenas causes the "arena" standard library package to be visible + // to the outside world. + Arenas bool + + // PageTrace enables GODEBUG=pagetrace=/path/to/result. This feature + // is a GOEXPERIMENT due to a security risk with setuid binaries: + // this compels the Go runtime to write to some arbitrary file, which + // may be exploited. + PageTrace bool + + // CgoCheck2 enables an expensive cgo rule checker. + // When this experiment is enabled, cgo rule checks occur regardless + // of the GODEBUG=cgocheck setting provided at runtime. + CgoCheck2 bool + + // LoopVar changes loop semantics so that each iteration gets its own + // copy of the iteration variable. + LoopVar bool + + // CacheProg adds support to cmd/go to use a child process to implement + // the build cache; see https://github.com/golang/go/issues/59719. + CacheProg bool + + // NewInliner enables a new+improved version of the function + // inlining phase within the Go compiler. + NewInliner bool + + // RangeFunc enables range over func. + RangeFunc bool + + // Range enables range over int and func. + Range bool + + // AllocHeaders enables a different, more efficient way for the GC to + // manage heap metadata. + AllocHeaders bool + + // ExecTracer2 controls whether to use the new execution trace + // implementation. + ExecTracer2 bool +} |