github.com/JimmyHuang454/JLS-go@v0.0.0-20230831150107-90d536585ba0/internal/goexperiment/flags.go (about)

     1  // Copyright 2021 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package goexperiment implements support for toolchain experiments.
     6  //
     7  // Toolchain experiments are controlled by the GOEXPERIMENT
     8  // environment variable. GOEXPERIMENT is a comma-separated list of
     9  // experiment names. GOEXPERIMENT can be set at make.bash time, which
    10  // sets the default experiments for binaries built with the tool
    11  // chain; or it can be set at build time. GOEXPERIMENT can also be set
    12  // to "none", which disables any experiments that were enabled at
    13  // make.bash time.
    14  //
    15  // Experiments are exposed to the build in the following ways:
    16  //
    17  // - Build tag goexperiment.x is set if experiment x (lower case) is
    18  // enabled.
    19  //
    20  // - For each experiment x (in camel case), this package contains a
    21  // boolean constant x and an integer constant xInt.
    22  //
    23  // - In runtime assembly, the macro GOEXPERIMENT_x is defined if
    24  // experiment x (lower case) is enabled.
    25  //
    26  // In the toolchain, the set of experiments enabled for the current
    27  // build should be accessed via objabi.Experiment.
    28  //
    29  // The set of experiments is included in the output of runtime.Version()
    30  // and "go version <binary>" if it differs from the default experiments.
    31  //
    32  // For the set of experiments supported by the current toolchain, see
    33  // "go doc goexperiment.Flags".
    34  //
    35  // Note that this package defines the set of experiments (in Flags)
    36  // and records the experiments that were enabled when the package
    37  // was compiled (as boolean and integer constants).
    38  //
    39  // Note especially that this package does not itself change behavior
    40  // at run time based on the GOEXPERIMENT variable.
    41  // The code used in builds to interpret the GOEXPERIMENT variable
    42  // is in the separate package internal/buildcfg.
    43  package goexperiment
    44  
    45  //go:generate go run mkconsts.go
    46  
    47  // Flags is the set of experiments that can be enabled or disabled in
    48  // the current toolchain.
    49  //
    50  // When specified in the GOEXPERIMENT environment variable or as build
    51  // tags, experiments use the strings.ToLower of their field name.
    52  //
    53  // For the baseline experimental configuration, see
    54  // objabi.experimentBaseline.
    55  //
    56  // If you change this struct definition, run "go generate".
    57  type Flags struct {
    58  	FieldTrack        bool
    59  	PreemptibleLoops  bool
    60  	StaticLockRanking bool
    61  	BoringCrypto      bool
    62  
    63  	// Unified enables the compiler's unified IR construction
    64  	// experiment.
    65  	Unified bool
    66  
    67  	// Regabi is split into several sub-experiments that can be
    68  	// enabled individually. Not all combinations work.
    69  	// The "regabi" GOEXPERIMENT is an alias for all "working"
    70  	// subexperiments.
    71  
    72  	// RegabiWrappers enables ABI wrappers for calling between
    73  	// ABI0 and ABIInternal functions. Without this, the ABIs are
    74  	// assumed to be identical so cross-ABI calls are direct.
    75  	RegabiWrappers bool
    76  	// RegabiArgs enables register arguments/results in all
    77  	// compiled Go functions.
    78  	//
    79  	// Requires wrappers (to do ABI translation), and reflect (so
    80  	// reflection calls use registers).
    81  	RegabiArgs bool
    82  
    83  	// HeapMinimum512KiB reduces the minimum heap size to 512 KiB.
    84  	//
    85  	// This was originally reduced as part of PacerRedesign, but
    86  	// has been broken out to its own experiment that is disabled
    87  	// by default.
    88  	HeapMinimum512KiB bool
    89  
    90  	// CoverageRedesign enables the new compiler-based code coverage
    91  	// tooling.
    92  	CoverageRedesign bool
    93  
    94  	// Arenas causes the "arena" standard library package to be visible
    95  	// to the outside world.
    96  	Arenas bool
    97  
    98  	// PageTrace enables GODEBUG=pagetrace=/path/to/result. This feature
    99  	// is a GOEXPERIMENT due to a security risk with setuid binaries:
   100  	// this compels the Go runtime to write to some arbitrary file, which
   101  	// may be exploited.
   102  	PageTrace bool
   103  }