cmd: move GOEXPERIMENT knob from make.bash to cmd/go

This CL changes GOEXPERIMENT to act like other GO[CONFIG] environment
variables. Namely, that it can be set at make.bash time to provide a
default value used by the toolchain, but then can be manually set when
running either cmd/go or the individual tools (compiler, assembler,
linker).

For example, it's now possible to test rsc.io/tmp/fieldtrack by simply
running:

GOEXPERIMENT=fieldtrack go test -gcflags=-l rsc.io/tmp/fieldtrack \
  -ldflags=-k=rsc.io/tmp/fieldtrack.tracked

without needing to re-run make.bash. (-gcflags=-l is needed because
the compiler's inlining abilities have improved, so calling a function
with a for loop is no longer sufficient to suppress inlining.)

Fixes #42681.

Change-Id: I2cf8995d5d0d05f6785a2ee1d3b54b2cfb3331ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/300991
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

diff --git a/src/cmd/asm/internal/lex/input.go b/src/cmd/asm/internal/lex/input.go
index da4ebe6d6e3447fa5a672863b68e459b720646ec..1d4d4be7bd6db30ca7c69e4cf3ba5e5465cb65d5 100644 (file)
--- a/src/cmd/asm/internal/lex/input.go
+++ b/src/cmd/asm/internal/lex/input.go
@@ -45,6 +45,16 @@ func NewInput(name string) *Input {
 // predefine installs the macros set by the -D flag on the command line.
 func predefine(defines flags.MultiFlag) map[string]*Macro {
        macros := make(map[string]*Macro)
+
+       if *flags.CompilingRuntime && objabi.Regabi_enabled != 0 {
+               const name = "GOEXPERIMENT_REGABI"
+               macros[name] = &Macro{
+                       name:   name,
+                       args:   nil,
+                       tokens: Tokenize("1"),
+               }
+       }
+
        for _, name := range defines {
                value := "1"
                i := strings.IndexRune(name, '=')

diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 158cedbadc4e390d3728648b7ed06849255f8719..b2d13e7db481032175f65a6485d3f956faa38589 100644 (file)
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -39,6 +39,7 @@ var (
        goextlinkenabled string
        gogcflags        string // For running built compiler
        goldflags        string
+       goexperiment     string
        workdir          string
        tooldir          string
        oldgoos          string
@@ -194,6 +195,9 @@ func xinit() {
                goextlinkenabled = b
        }
 
+       goexperiment = os.Getenv("GOEXPERIMENT")
+       // TODO(mdempsky): Validate known experiments?
+
        gogcflags = os.Getenv("BOOT_GO_GCFLAGS")
        goldflags = os.Getenv("BOOT_GO_LDFLAGS")
 
@@ -834,18 +838,6 @@ func runInstall(pkg string, ch chan struct{}) {
        goasmh := pathf("%s/go_asm.h", workdir)
        if IsRuntimePackagePath(pkg) {
                asmArgs = append(asmArgs, "-compiling-runtime")
-               if os.Getenv("GOEXPERIMENT") == "regabi" {
-                       // In order to make it easier to port runtime assembly
-                       // to the register ABI, we introduce a macro
-                       // indicating the experiment is enabled.
-                       //
-                       // Note: a similar change also appears in
-                       // cmd/go/internal/work/gc.go.
-                       //
-                       // TODO(austin): Remove this once we commit to the
-                       // register ABI (#40724).
-                       asmArgs = append(asmArgs, "-D=GOEXPERIMENT_REGABI=1")
-               }
        }
 
        // Collect symabis from assembly code.

diff --git a/src/cmd/dist/buildruntime.go b/src/cmd/dist/buildruntime.go
index 27449515976b36449ecd7a92c3341d3a98fbb832..e0a101a3532428a2d94fa2ae89edf005784b47c8 100644 (file)
--- a/src/cmd/dist/buildruntime.go
+++ b/src/cmd/dist/buildruntime.go
@@ -20,7 +20,6 @@ import (
 //     package sys
 //
 //     const TheVersion = <version>
-//     const Goexperiment = <goexperiment>
 //     const StackGuardMultiplier = <multiplier value>
 //
 func mkzversion(dir, file string) {
@@ -30,7 +29,6 @@ func mkzversion(dir, file string) {
        fmt.Fprintf(&buf, "package sys\n")
        fmt.Fprintln(&buf)
        fmt.Fprintf(&buf, "const TheVersion = `%s`\n", findgoversion())
-       fmt.Fprintf(&buf, "const Goexperiment = `%s`\n", os.Getenv("GOEXPERIMENT"))
        fmt.Fprintf(&buf, "const StackGuardMultiplierDefault = %d\n", stackGuardMultiplierDefault())
 
        writefile(buf.String(), file, writeSkipSame)
@@ -48,10 +46,10 @@ func mkzversion(dir, file string) {
 //     const defaultGOPPC64 = <goppc64>
 //     const defaultGOOS = runtime.GOOS
 //     const defaultGOARCH = runtime.GOARCH
+//     const defaultGOEXPERIMENT = <goexperiment>
 //     const defaultGO_EXTLINK_ENABLED = <goextlinkenabled>
 //     const version = <version>
 //     const stackGuardMultiplierDefault = <multiplier value>
-//     const goexperiment = <goexperiment>
 //
 // The use of runtime.GOOS and runtime.GOARCH makes sure that
 // a cross-compiled compiler expects to compile for its own target
@@ -77,11 +75,11 @@ func mkzbootstrap(file string) {
        fmt.Fprintf(&buf, "const defaultGOPPC64 = `%s`\n", goppc64)
        fmt.Fprintf(&buf, "const defaultGOOS = runtime.GOOS\n")
        fmt.Fprintf(&buf, "const defaultGOARCH = runtime.GOARCH\n")
+       fmt.Fprintf(&buf, "const defaultGOEXPERIMENT = `%s`\n", goexperiment)
        fmt.Fprintf(&buf, "const defaultGO_EXTLINK_ENABLED = `%s`\n", goextlinkenabled)
        fmt.Fprintf(&buf, "const defaultGO_LDSO = `%s`\n", defaultldso)
        fmt.Fprintf(&buf, "const version = `%s`\n", findgoversion())
        fmt.Fprintf(&buf, "const stackGuardMultiplierDefault = %d\n", stackGuardMultiplierDefault())
-       fmt.Fprintf(&buf, "const goexperiment = `%s`\n", os.Getenv("GOEXPERIMENT"))
 
        writefile(buf.String(), file, writeSkipSame)
 }

diff --git a/src/cmd/go/internal/cfg/cfg.go b/src/cmd/go/internal/cfg/cfg.go
index 810189c15d782589d8aa3acce6cde782680db282..a91b6a57b98b6a36cb884e36dce37ddd50f66cb7 100644 (file)
--- a/src/cmd/go/internal/cfg/cfg.go
+++ b/src/cmd/go/internal/cfg/cfg.go
@@ -252,12 +252,13 @@ var (
        GOMODCACHE   = envOr("GOMODCACHE", gopathDir("pkg/mod"))
 
        // Used in envcmd.MkEnv and build ID computations.
-       GOARM    = envOr("GOARM", fmt.Sprint(objabi.GOARM))
-       GO386    = envOr("GO386", objabi.GO386)
-       GOMIPS   = envOr("GOMIPS", objabi.GOMIPS)
-       GOMIPS64 = envOr("GOMIPS64", objabi.GOMIPS64)
-       GOPPC64  = envOr("GOPPC64", fmt.Sprintf("%s%d", "power", objabi.GOPPC64))
-       GOWASM   = envOr("GOWASM", fmt.Sprint(objabi.GOWASM))
+       GOARM        = envOr("GOARM", fmt.Sprint(objabi.GOARM))
+       GO386        = envOr("GO386", objabi.GO386)
+       GOMIPS       = envOr("GOMIPS", objabi.GOMIPS)
+       GOMIPS64     = envOr("GOMIPS64", objabi.GOMIPS64)
+       GOPPC64      = envOr("GOPPC64", fmt.Sprintf("%s%d", "power", objabi.GOPPC64))
+       GOWASM       = envOr("GOWASM", fmt.Sprint(objabi.GOWASM))
+       GOEXPERIMENT = envOr("GOEXPERIMENT", objabi.GOEXPERIMENT)
 
        GOPROXY    = envOr("GOPROXY", "https://proxy.golang.org,direct")
        GOSUMDB    = envOr("GOSUMDB", "sum.golang.org")

diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 3980c5f89848cdf32d3481630718c127a144a530..bd5ae467393b498413d2bdffccc2bd11cf534156 100644 (file)
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -276,6 +276,10 @@ func (b *Builder) buildActionID(a *Action) cache.ActionID {
                key, val := cfg.GetArchEnv()
                fmt.Fprintf(h, "%s=%s\n", key, val)
 
+               if exp := cfg.Getenv("GOEXPERIMENT"); exp != "" {
+                       fmt.Fprintf(h, "GOEXPERIMENT=%q\n", exp)
+               }
+
                // TODO(rsc): Convince compiler team not to add more magic environment variables,
                // or perhaps restrict the environment variables passed to subprocesses.
                // Because these are clumsy, undocumented special-case hacks
@@ -1246,6 +1250,10 @@ func (b *Builder) printLinkerConfig(h io.Writer, p *load.Package) {
                key, val := cfg.GetArchEnv()
                fmt.Fprintf(h, "%s=%s\n", key, val)
 
+               if exp := cfg.Getenv("GOEXPERIMENT"); exp != "" {
+                       fmt.Fprintf(h, "GOEXPERIMENT=%q\n", exp)
+               }
+
                // The linker writes source file paths that say GOROOT_FINAL, but
                // only if -trimpath is not specified (see ld() in gc.go).
                gorootFinal := cfg.GOROOT_FINAL

diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index 2087855b3c04a96c632f22f93875612a5b91c749..3cb7c5aff3d950c1bb61c6560c33da1163871515 100644 (file)
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -343,18 +343,6 @@ func asmArgs(a *Action, p *load.Package) []interface{} {
        }
        if objabi.IsRuntimePackagePath(pkgpath) {
                args = append(args, "-compiling-runtime")
-               if objabi.Regabi_enabled != 0 {
-                       // In order to make it easier to port runtime assembly
-                       // to the register ABI, we introduce a macro
-                       // indicating the experiment is enabled.
-                       //
-                       // Note: a similar change also appears in
-                       // cmd/dist/build.go.
-                       //
-                       // TODO(austin): Remove this once we commit to the
-                       // register ABI (#40724).
-                       args = append(args, "-D=GOEXPERIMENT_REGABI=1")
-               }
        }
 
        if cfg.Goarch == "mips" || cfg.Goarch == "mipsle" {

diff --git a/src/cmd/internal/objabi/util.go b/src/cmd/internal/objabi/util.go
index 1f99f8ed5d66279f054ea9f3a95392fa5751f02d..de8e6de4e6c011603540959ef756dde29fc505fc 100644 (file)
--- a/src/cmd/internal/objabi/util.go
+++ b/src/cmd/internal/objabi/util.go
@@ -21,17 +21,18 @@ func envOr(key, value string) string {
 var (
        defaultGOROOT string // set by linker
 
-       GOROOT   = envOr("GOROOT", defaultGOROOT)
-       GOARCH   = envOr("GOARCH", defaultGOARCH)
-       GOOS     = envOr("GOOS", defaultGOOS)
-       GO386    = envOr("GO386", defaultGO386)
-       GOARM    = goarm()
-       GOMIPS   = gomips()
-       GOMIPS64 = gomips64()
-       GOPPC64  = goppc64()
-       GOWASM   = gowasm()
-       GO_LDSO  = defaultGO_LDSO
-       Version  = version
+       GOROOT       = envOr("GOROOT", defaultGOROOT)
+       GOARCH       = envOr("GOARCH", defaultGOARCH)
+       GOOS         = envOr("GOOS", defaultGOOS)
+       GOEXPERIMENT = envOr("GOEXPERIMENT", defaultGOEXPERIMENT)
+       GO386        = envOr("GO386", defaultGO386)
+       GOARM        = goarm()
+       GOMIPS       = gomips()
+       GOMIPS64     = gomips64()
+       GOPPC64      = goppc64()
+       GOWASM       = gowasm()
+       GO_LDSO      = defaultGO_LDSO
+       Version      = version
 )
 
 const (
@@ -124,7 +125,7 @@ func Getgoextlinkenabled() string {
 }
 
 func init() {
-       for _, f := range strings.Split(goexperiment, ",") {
+       for _, f := range strings.Split(GOEXPERIMENT, ",") {
                if f != "" {
                        addexp(f)
                }

diff --git a/src/cmd/link/internal/ld/main.go b/src/cmd/link/internal/ld/main.go
index 68dee1859878b7e0d1d7a8f061fa1c67d21219a8..8e9a9b920778697f32a6f1286a5757026a9a65cc 100644 (file)
--- a/src/cmd/link/internal/ld/main.go
+++ b/src/cmd/link/internal/ld/main.go
@@ -119,6 +119,8 @@ func Main(arch *sys.Arch, theArch Arch) {
        addstrdata1(ctxt, "runtime.defaultGOROOT="+final)
        addstrdata1(ctxt, "cmd/internal/objabi.defaultGOROOT="+final)
 
+       addstrdata1(ctxt, "runtime/internal/sys.GOEXPERIMENT="+objabi.GOEXPERIMENT)
+
        // TODO(matloob): define these above and then check flag values here
        if ctxt.Arch.Family == sys.AMD64 && objabi.GOOS == "plan9" {
                flag.BoolVar(&flag8, "8", false, "use 64-bit addresses in symbol table")

diff --git a/src/internal/cfg/cfg.go b/src/internal/cfg/cfg.go
index 553021374d5f1c0dff5317297c9268eaa8c0e0e5..815994b679ac3c70658822a155d9981e4576da54 100644 (file)
--- a/src/internal/cfg/cfg.go
+++ b/src/internal/cfg/cfg.go
@@ -39,6 +39,7 @@ const KnownEnv = `
        GOCACHE
        GOENV
        GOEXE
+       GOEXPERIMENT
        GOFLAGS
        GOGCCFLAGS
        GOHOSTARCH

diff --git a/src/runtime/heapdump.go b/src/runtime/heapdump.go
index 1b8c19b4768dc4592f7ba81e6d59e2eddc8fedef..e0913162a431484ed0da158a70de0f6bb9f872e2 100644 (file)
--- a/src/runtime/heapdump.go
+++ b/src/runtime/heapdump.go
@@ -532,7 +532,7 @@ func dumpparams() {
        dumpint(uint64(arenaStart))
        dumpint(uint64(arenaEnd))
        dumpstr(sys.GOARCH)
-       dumpstr(sys.Goexperiment)
+       dumpstr(sys.GOEXPERIMENT)
        dumpint(uint64(ncpu))
 }
 

diff --git a/src/runtime/internal/sys/arch.go b/src/runtime/internal/sys/arch.go
index 3c99a2f7da0831048e2aa5ae24cb8914e5d83785..f00c55913f824693526a144c06a718c957fd573b 100644 (file)
--- a/src/runtime/internal/sys/arch.go
+++ b/src/runtime/internal/sys/arch.go
@@ -52,3 +52,5 @@ const MinFrameSize = _MinFrameSize
 // StackAlign is the required alignment of the SP register.
 // The stack must be at least word aligned, but some architectures require more.
 const StackAlign = _StackAlign
+
+var GOEXPERIMENT string // set by cmd/link

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 5f372bb06363f19b991b0cdc85fb938be8c28c09..8db3b767d111de35ff63882035a9a86ff7eb3cd0 100644 (file)
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -6027,7 +6027,7 @@ func setMaxThreads(in int) (out int) {
 }
 
 func haveexperiment(name string) bool {
-       x := sys.Goexperiment
+       x := sys.GOEXPERIMENT
        for x != "" {
                xname := ""
                i := bytealg.IndexByteString(x, ',')