From: Matthew Dempsky <mdempsky@google.com>
Date: Tue, 28 Feb 2017 23:51:29 +0000 (-0800)
Subject: cmd/compile/internal/gc: separate builtin and real runtime packages
X-Git-Tag: go1.9beta1~1377
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=b6c600fc9a75fd6f4b6f4478058b95902ae6be94;p=gostls13.git

cmd/compile/internal/gc: separate builtin and real runtime packages

The builtin runtime package definitions intentionally diverge from the
actual runtime package's, but this only works as long as they never
overlap.

To make it easier to expand the builtin runtime package, this CL now
loads their definitions into a logically separate "go.runtime"
package.  By resetting the package's Prefix field to "runtime", any
references to builtin definitions will still resolve against the real
package runtime.

Fixes #14482.

Passes toolstash -cmp.

Change-Id: I539c0994deaed4506a331f38c5b4d6bc8c95433f
Reviewed-on: https://go-review.googlesource.com/37538
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
---

diff --git a/src/cmd/compile/internal/gc/go.go b/src/cmd/compile/internal/gc/go.go
index 95c1124f9e..9bf4b49395 100644
--- a/src/cmd/compile/internal/gc/go.go
+++ b/src/cmd/compile/internal/gc/go.go
@@ -27,6 +27,14 @@ type Pkg struct {
 	Syms     map[string]*Sym
 }
 
+// isRuntime reports whether p is package runtime.
+func (p *Pkg) isRuntime() bool {
+	if compiling_runtime && p == localpkg {
+		return true
+	}
+	return p.Path == "runtime"
+}
+
 // Sym represents an object name. Most commonly, this is a Go identifier naming
 // an object declared within a package, but Syms are also used to name internal
 // synthesized objects.
@@ -153,7 +161,7 @@ var itabpkg *Pkg // fake pkg for itab entries
 
 var itablinkpkg *Pkg // fake package for runtime itab entries
 
-var Runtimepkg *Pkg // package runtime
+var Runtimepkg *Pkg // fake package runtime
 
 var racepkg *Pkg // package runtime/race
 
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index 2b1ae860d6..b9350d33e0 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -124,9 +124,14 @@ func Main() {
 	unsafepkg = mkpkg("unsafe")
 	unsafepkg.Name = "unsafe"
 
-	// real package, referred to by generated runtime calls
-	Runtimepkg = mkpkg("runtime")
+	// Pseudo-package that contains the compiler's builtin
+	// declarations for package runtime. These are declared in a
+	// separate package to avoid conflicts with package runtime's
+	// actual declarations, which may differ intentionally but
+	// insignificantly.
+	Runtimepkg = mkpkg("go.runtime")
 	Runtimepkg.Name = "runtime"
+	Runtimepkg.Prefix = "runtime"
 
 	// pseudo-packages used in symbol tables
 	itabpkg = mkpkg("go.itab")
diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go
index 1aca44bce5..7b26b870c5 100644
--- a/src/cmd/compile/internal/gc/typecheck.go
+++ b/src/cmd/compile/internal/gc/typecheck.go
@@ -1289,7 +1289,7 @@ OpSwitch:
 		if t.Results().NumFields() == 1 {
 			n.Type = l.Type.Results().Field(0).Type
 
-			if n.Op == OCALLFUNC && n.Left.Op == ONAME && (compiling_runtime || n.Left.Sym.Pkg == Runtimepkg) && n.Left.Sym.Name == "getg" {
+			if n.Op == OCALLFUNC && n.Left.Op == ONAME && n.Left.Sym.Pkg.isRuntime() && n.Left.Sym.Name == "getg" {
 				// Emit code for runtime.getg() directly instead of calling function.
 				// Most such rewrites (for example the similar one for math.Sqrt) should be done in walk,
 				// so that the ordering pass can make sure to preserve the semantics of the original code
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index 96f66148a5..2ba994991b 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -1914,7 +1914,7 @@ func walkprint(nn *Node, init *Nodes) *Node {
 			on = substArgTypes(on, n.Type) // any-1
 		} else if isInt[et] {
 			if et == TUINT64 {
-				if (t.Sym.Pkg == Runtimepkg || compiling_runtime) && t.Sym.Name == "hex" {
+				if t.Sym.Pkg.isRuntime() && t.Sym.Name == "hex" {
 					on = syslook("printhex")
 				} else {
 					on = syslook("printuint")
diff --git a/test/runtime.go b/test/runtime.go
index bccc9b53af..0cf781b814 100644
--- a/test/runtime.go
+++ b/test/runtime.go
@@ -17,5 +17,5 @@ package main
 import "runtime"
 
 func main() {
-	runtime.printbool(true)	// ERROR "unexported"
+	runtime.printbool(true)	// ERROR "unexported" "undefined"
 }