cmd/link: enable internal linking by default on darwin/arm64

With previous CLs, internal linking without cgo should work well.
Enable it by default. And stop always requiring cgo.

Enable tests that were previously disabled due to the lack of
internal linking.

Updates #38485.

Change-Id: I45125b9c263fd21d6847aa6b14ecaea3a2989b29
Reviewed-on: https://go-review.googlesource.com/c/go/+/265121
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

7 files changed, 3 insertions, 22 deletions

diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 4c541b9017..ff744ee9fa 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -1964,10 +1964,6 @@ func externalLinkingForced(p *Package) bool {
 		}
 	case "ios":
 		return true
-	case "darwin":
-		if cfg.BuildContext.GOARCH == "arm64" {
-			return true
-		}
 	}
 
 	// Currently build modes c-shared, pie (on systems that do not
diff --git a/src/cmd/internal/sys/supported.go b/src/cmd/internal/sys/supported.go
index 1d813bbb47..afc81381fd 100644
--- a/src/cmd/internal/sys/supported.go
+++ b/src/cmd/internal/sys/supported.go
@@ -39,7 +39,7 @@ func MustLinkExternal(goos, goarch string) bool {
 		if goarch != "arm64" {
 			return true
 		}
-	case "darwin", "ios":
+	case "ios":
 		if goarch == "arm64" {
 			return true
 		}
diff --git a/src/cmd/link/internal/ld/config.go b/src/cmd/link/internal/ld/config.go
index 54a94cebba..0cb3cc25c0 100644
--- a/src/cmd/link/internal/ld/config.go
+++ b/src/cmd/link/internal/ld/config.go
@@ -185,7 +185,7 @@ func mustLinkExternal(ctxt *Link) (res bool, reason string) {
 		}()
 	}
 
-	if sys.MustLinkExternal(objabi.GOOS, objabi.GOARCH) && !(objabi.GOOS == "darwin" && objabi.GOARCH == "arm64") { // XXX allow internal linking for darwin/arm64 but not change the default
+	if sys.MustLinkExternal(objabi.GOOS, objabi.GOARCH) {
 		return true, fmt.Sprintf("%s/%s requires external linking", objabi.GOOS, objabi.GOARCH)
 	}
 
@@ -261,8 +261,6 @@ func determineLinkMode(ctxt *Link) {
 		default:
 			if extNeeded || (iscgo && externalobj) {
 				ctxt.LinkMode = LinkExternal
-			} else if ctxt.IsDarwin() && ctxt.IsARM64() {
-				ctxt.LinkMode = LinkExternal // default to external linking for now
 			} else {
 				ctxt.LinkMode = LinkInternal
 			}
diff --git a/src/cmd/nm/nm_cgo_test.go b/src/cmd/nm/nm_cgo_test.go
index 58f2c24908..9a257e0ed2 100644
--- a/src/cmd/nm/nm_cgo_test.go
+++ b/src/cmd/nm/nm_cgo_test.go
@@ -15,11 +15,6 @@ func canInternalLink() bool {
 	switch runtime.GOOS {
 	case "aix":
 		return false
-	case "darwin":
-		switch runtime.GOARCH {
-		case "arm64":
-			return false
-		}
 	case "dragonfly":
 		return false
 	case "freebsd":
diff --git a/src/internal/testenv/testenv.go b/src/internal/testenv/testenv.go
index 0ee6355ee3..dff68869bd 100644
--- a/src/internal/testenv/testenv.go
+++ b/src/internal/testenv/testenv.go
@@ -201,7 +201,7 @@ func CanInternalLink() bool {
 		if runtime.GOARCH != "arm64" {
 			return false
 		}
-	case "darwin", "ios":
+	case "ios":
 		if runtime.GOARCH == "arm64" {
 			return false
 		}
diff --git a/test/fixedbugs/bug429_run.go b/test/fixedbugs/bug429_run.go
index 60cc5b62de..c2bb1b85cb 100644
--- a/test/fixedbugs/bug429_run.go
+++ b/test/fixedbugs/bug429_run.go
@@ -1,10 +1,6 @@
 // run
 
 // +build !nacl,!js
-// +build !darwin !arm64
-
-// Skip on darwin/arm64 as it requires external linking, which brings in
-// cgo, causing deadlock detection not working.
 
 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/test/fixedbugs/issue21576.go b/test/fixedbugs/issue21576.go
index 3797a8c9ba..ae6161ccf5 100644
--- a/test/fixedbugs/issue21576.go
+++ b/test/fixedbugs/issue21576.go
@@ -1,10 +1,6 @@
 // run
 
 // +build !nacl,!js
-// +build !darwin !arm64
-
-// Skip on darwin/arm64 as it requires external linking, which brings in
-// cgo, causing deadlock detection not working.
 
 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style