cmd/link: skip arch-specific main function

Add some notes to main.go on what happens where.

Change-Id: I4fb0b6c280e5f990ddc5d749267372b86870af6d
Reviewed-on: https://go-review.googlesource.com/28970
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/link/internal/amd64/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	ld.SysArch = sys.ArchAMD64
 	if obj.GOARCH == "amd64p32" {
 		ld.SysArch = sys.ArchAMD64P32

src/cmd/link/internal/arm/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	ld.SysArch = sys.ArchARM
 
 	ld.Thearch.Funcalign = FuncAlign

src/cmd/link/internal/arm64/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	ld.SysArch = sys.ArchARM64
 
 	ld.Thearch.Funcalign = FuncAlign

src/cmd/link/internal/mips64/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	if obj.GOARCH == "mips64le" {
 		ld.SysArch = sys.ArchMIPS64LE
 	} else {

src/cmd/link/internal/ppc64/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	if obj.GOARCH == "ppc64le" {
 		ld.SysArch = sys.ArchPPC64LE
 	} else {

src/cmd/link/internal/s390x/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	ld.SysArch = sys.ArchS390X
 
 	ld.Thearch.Funcalign = FuncAlign

src/cmd/link/internal/x86/obj.go

@@ -37,14 +37,7 @@ import (
 	"fmt"
 )
 
-// Reading object files.
-
-func Main() {
-	linkarchinit()
-	ld.Main()
-}
-
-func linkarchinit() {
+func Init() {
 	ld.SysArch = sys.Arch386
 
 	ld.Thearch.Funcalign = FuncAlign

src/cmd/link/main.go

@@ -9,6 +9,7 @@ import (
 	"cmd/link/internal/amd64"
 	"cmd/link/internal/arm"
 	"cmd/link/internal/arm64"
+	"cmd/link/internal/ld"
 	"cmd/link/internal/mips64"
 	"cmd/link/internal/ppc64"
 	"cmd/link/internal/s390x"
@@ -17,24 +18,39 @@ import (
 	"os"
 )
 
+// The bulk of the linker implementation lives in cmd/link/internal/ld.
+// Architecture-specific code lives in cmd/link/internal/GOARCH.
+//
+// Program initialization:
+//
+// Before any argument parsing is done, the Init function of relevant
+// architecture package is called. The only job done in Init is
+// configuration of the ld.Thearch and ld.SysArch variables.
+//
+// Then control flow passes to ld.Main, which parses flags, makes
+// some configuration decisions, and then gives the architecture
+// packages a second chance to modify the linker's configuration
+// via the ld.Thearch.Archinit function.
+
 func main() {
 	switch obj.GOARCH {
 	default:
 		fmt.Fprintf(os.Stderr, "link: unknown architecture %q\n", obj.GOARCH)
 		os.Exit(2)
 	case "386":
-		x86.Main()
+		x86.Init()
 	case "amd64", "amd64p32":
-		amd64.Main()
+		amd64.Init()
 	case "arm":
-		arm.Main()
+		arm.Init()
 	case "arm64":
-		arm64.Main()
+		arm64.Init()
 	case "mips64", "mips64le":
-		mips64.Main()
+		mips64.Init()
 	case "ppc64", "ppc64le":
-		ppc64.Main()
+		ppc64.Init()
 	case "s390x":
-		s390x.Main()
+		s390x.Init()
 	}
+	ld.Main()
 }