From: Austin Clements <austin@google.com>
Date: Wed, 17 Mar 2021 16:22:58 +0000 (-0400)
Subject: cmd/internal/objabi,runtime: simplify sys.GOEXPERIMENT parsing
X-Git-Tag: go1.17beta1~1052
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=095ba225973152734b0722e7c5758accb2639c15;p=gostls13.git

cmd/internal/objabi,runtime: simplify sys.GOEXPERIMENT parsing

Previously, the runtime had to understand the full syntax of the
GOEXPERIMENT environment variable. Now, sys.GOEXPERIMENT is the
pre-processed experiment list produced by objabi, so we can simplify
the runtime parser.

Change-Id: I0d113a4347dde50a35b8b1f2b0110c88fe802921
Reviewed-on: https://go-review.googlesource.com/c/go/+/303049
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
---

diff --git a/src/cmd/internal/objabi/util.go b/src/cmd/internal/objabi/util.go
index 9fbe6490e0..2a33f0d84a 100644
--- a/src/cmd/internal/objabi/util.go
+++ b/src/cmd/internal/objabi/util.go
@@ -171,6 +171,7 @@ func init() {
 	}
 
 	// Set GOEXPERIMENT to the parsed and canonicalized set of experiments.
+	// This format must be parseable by runtime.haveexperiment.
 	GOEXPERIMENT = expList()
 }
 
@@ -184,7 +185,7 @@ func init() {
 var FramePointerEnabled = GOARCH == "amd64" || GOARCH == "arm64"
 
 func addexp(s string) {
-	// Could do general integer parsing here, but the runtime.haveexperiment doesn't yet.
+	// We could do general integer parsing here, but there's no need yet.
 	v, vb := 1, true
 	name := s
 	if len(name) > 2 && name[:2] == "no" {
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 9ebfe70883..a666f86abc 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -6027,6 +6027,9 @@ func setMaxThreads(in int) (out int) {
 }
 
 func haveexperiment(name string) bool {
+	// GOEXPERIMENT is a comma-separated list of enabled
+	// experiments. It's not the raw environment variable, but a
+	// pre-processed list from cmd/internal/objabi.
 	x := sys.GOEXPERIMENT
 	for x != "" {
 		xname := ""
@@ -6039,9 +6042,6 @@ func haveexperiment(name string) bool {
 		if xname == name {
 			return true
 		}
-		if len(xname) > 2 && xname[:2] == "no" && xname[2:] == name {
-			return false
-		}
 	}
 	return false
 }