runtime: generate windows callback list with go generate

This is the last system-dependent file written by cmd/dist.
They are all now written by go generate.

cmd/dist is not needed to start building package runtime
for a different system anymore.

Now all the generated files can be assumed generated, so
delete the clumsy hacks in cmd/api.

Re-enable api check in run.bash.

LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://codereview.appspot.com/185040044

4 files changed, 15 insertions, 200 deletions

diff --git a/src/cmd/api/goapi.go b/src/cmd/api/goapi.go
index 5a8c87603..568aec8c0 100644
--- a/src/cmd/api/goapi.go
+++ b/src/cmd/api/goapi.go
@@ -352,139 +352,16 @@ var parsedFileCache = make(map[string]*ast.File)
 
 func (w *Walker) parseFile(dir, file string) (*ast.File, error) {
 	filename := filepath.Join(dir, file)
-	f, _ := parsedFileCache[filename]
-	if f != nil {
+	if f := parsedFileCache[filename]; f != nil {
 		return f, nil
 	}
 
-	var err error
-
-	// generate missing context-dependent files.
-
-	if w.context != nil && file == fmt.Sprintf("zgoos_%s.go", w.context.GOOS) {
-		src := fmt.Sprintf("package runtime; const theGoos = `%s`", w.context.GOOS)
-		f, err = parser.ParseFile(fset, filename, src, 0)
-		if err != nil {
-			log.Fatalf("incorrect generated file: %s", err)
-		}
-	}
-
-	if w.context != nil && file == fmt.Sprintf("zgoarch_%s.go", w.context.GOARCH) {
-		src := fmt.Sprintf("package runtime; const theGoarch = `%s`", w.context.GOARCH)
-		f, err = parser.ParseFile(fset, filename, src, 0)
-		if err != nil {
-			log.Fatalf("incorrect generated file: %s", err)
-		}
-	}
-	if w.context != nil && file == fmt.Sprintf("zruntime_defs_%s_%s.go", w.context.GOOS, w.context.GOARCH) {
-		// Just enough to keep the api checker happy. Keep sorted.
-		src := "package runtime; type (" +
-			" _defer struct{};" +
-			" _func struct{};" +
-			" _panic struct{};" +
-			" _select struct{}; " +
-			" _type struct{};" +
-			" alg struct{};" +
-			" chantype struct{};" +
-			" context struct{};" + // windows
-			" eface struct{};" +
-			" epollevent struct{};" +
-			" funcval struct{};" +
-			" g struct{};" +
-			" gobuf struct{};" +
-			" hchan struct{};" +
-			" iface struct{};" +
-			" interfacetype struct{};" +
-			" itab struct{};" +
-			" keventt struct{};" +
-			" m struct{};" +
-			" maptype struct{};" +
-			" mcache struct{};" +
-			" mspan struct{};" +
-			" mutex struct{};" +
-			" note struct{};" +
-			" p struct{};" +
-			" parfor struct{};" +
-			" slicetype struct{};" +
-			" stkframe struct{};" +
-			" sudog struct{};" +
-			" timespec struct{};" +
-			" waitq struct{};" +
-			" wincallbackcontext struct{};" +
-			"); " +
-			"const (" +
-			" cb_max = 2000;" +
-			" _CacheLineSize = 64;" +
-			" _Gidle = 1;" +
-			" _Grunnable = 2;" +
-			" _Grunning = 3;" +
-			" _Gsyscall = 4;" +
-			" _Gwaiting = 5;" +
-			" _Gdead = 6;" +
-			" _Genqueue = 7;" +
-			" _Gcopystack = 8;" +
-			" _NSIG = 32;" +
-			" _FlagNoScan = iota;" +
-			" _FlagNoZero;" +
-			" _TinySize;" +
-			" _TinySizeClass;" +
-			" _MaxSmallSize;" +
-			" _PageShift;" +
-			" _PageSize;" +
-			" _PageMask;" +
-			" _BitsPerPointer;" +
-			" _BitsMask;" +
-			" _PointersPerByte;" +
-			" _MaxGCMask;" +
-			" _BitsDead;" +
-			" _BitsPointer;" +
-			" _MSpanInUse;" +
-			" _ConcurrentSweep;" +
-			" _KindBool;" +
-			" _KindInt;" +
-			" _KindInt8;" +
-			" _KindInt16;" +
-			" _KindInt32;" +
-			" _KindInt64;" +
-			" _KindUint;" +
-			" _KindUint8;" +
-			" _KindUint16;" +
-			" _KindUint32;" +
-			" _KindUint64;" +
-			" _KindUintptr;" +
-			" _KindFloat32;" +
-			" _KindFloat64;" +
-			" _KindComplex64;" +
-			" _KindComplex128;" +
-			" _KindArray;" +
-			" _KindChan;" +
-			" _KindFunc;" +
-			" _KindInterface;" +
-			" _KindMap;" +
-			" _KindPtr;" +
-			" _KindSlice;" +
-			" _KindString;" +
-			" _KindStruct;" +
-			" _KindUnsafePointer;" +
-			" _KindDirectIface;" +
-			" _KindGCProg;" +
-			" _KindNoPointers;" +
-			" _KindMask;" +
-			")"
-		f, err = parser.ParseFile(fset, filename, src, 0)
-		if err != nil {
-			log.Fatalf("incorrect generated file: %s", err)
-		}
-	}
-
-	if f == nil {
-		f, err = parser.ParseFile(fset, filename, nil, 0)
-		if err != nil {
-			return nil, err
-		}
+	f, err := parser.ParseFile(fset, filename, nil, 0)
+	if err != nil {
+		return nil, err
 	}
-
 	parsedFileCache[filename] = f
+
 	return f, nil
 }
 
@@ -591,25 +468,6 @@ func (w *Walker) Import(name string) (pkg *types.Package) {
 
 	filenames := append(append([]string{}, info.GoFiles...), info.CgoFiles...)
 
-	// Certain files only exist when building for the specified context.
-	// Add them manually.
-	if name == "runtime" {
-		n := fmt.Sprintf("zgoos_%s.go", w.context.GOOS)
-		if !contains(filenames, n) {
-			filenames = append(filenames, n)
-		}
-
-		n = fmt.Sprintf("zgoarch_%s.go", w.context.GOARCH)
-		if !contains(filenames, n) {
-			filenames = append(filenames, n)
-		}
-
-		n = fmt.Sprintf("zruntime_defs_%s_%s.go", w.context.GOOS, w.context.GOARCH)
-		if !contains(filenames, n) {
-			filenames = append(filenames, n)
-		}
-	}
-
 	// Parse package files.
 	var files []*ast.File
 	for _, file := range filenames {
diff --git a/src/cmd/dist/build.c b/src/cmd/dist/build.c
index bfb3d15b8..3743b7300 100644
--- a/src/cmd/dist/build.c
+++ b/src/cmd/dist/build.c
@@ -588,9 +588,6 @@ static struct {
 	}},
 	{"runtime", {
 		"zaexperiment.h",
-		"zsys_$GOOS_$GOARCH.s",
-		"zgoarch_$GOARCH.go",
-		"zgoos_$GOOS.go",
 		"zversion.go",
 	}},
 };
@@ -614,7 +611,6 @@ static struct {
 	{"anames8.c", mkanames},
 	{"anames9.c", mkanames},
 	{"zdefaultcc.go", mkzdefaultcc},
-	{"zsys_", mkzsys},
 	{"zversion.go", mkzversion},
 	{"zaexperiment.h", mkzexperiment},
 
@@ -1391,6 +1387,11 @@ static char *cleantab[] = {
 	"unicode/utf8",
 };
 
+static char *runtimegen[] = {
+	"zaexperiment.h",
+	"zversion.go",
+};
+
 static void
 clean(void)
 {
@@ -1417,15 +1418,11 @@ clean(void)
 			xremove(bpathf(&b, "%s/%s", bstr(&path), cleantab[i]+4));
 	}
 
-	// remove src/runtime/z* unconditionally,
+	// remove src/runtime/zaexperiment.h and 
 	// except leave zgoos and zgoarch, now maintained with go generate.
-	vreset(&dir);
 	bpathf(&path, "%s/src/runtime", goroot);
-	xreaddir(&dir, bstr(&path));
-	for(j=0; j<dir.len; j++) {
-		if(hasprefix(dir.p[j], "z") && !hasprefix(dir.p[j], "zg"))
-			xremove(bpathf(&b, "%s/%s", bstr(&path), dir.p[j]));
-	}
+	for(j=0; j<nelem(runtimegen); j++)
+		xremove(bpathf(&b, "%s/%s", bstr(&path), runtimegen[j]));
 
 	if(rebuildall) {
 		// Remove object tree.
diff --git a/src/cmd/dist/buildruntime.c b/src/cmd/dist/buildruntime.c
index 38e99e116..add689768 100644
--- a/src/cmd/dist/buildruntime.c
+++ b/src/cmd/dist/buildruntime.c
@@ -66,44 +66,3 @@ mkzexperiment(char *dir, char *file)
 	bfree(&out);
 	bfree(&exp);
 }
-
-#define MAXWINCB 2000 /* maximum number of windows callbacks allowed */
-
-// mkzsys writes zsys_$GOOS_$GOARCH.s,
-// which contains arch or os specific asm code.
-// 
-void
-mkzsys(char *dir, char *file)
-{
-	int i;
-	Buf out;
-
-	USED(dir);
-	
-	binit(&out);
-	
-	bwritestr(&out, "// auto generated by go tool dist\n\n");
-	if(streq(goos, "linux")) {
-		bwritestr(&out, "// +build !android\n\n");
-	}
-	
-	if(streq(goos, "windows")) {
-		bwritef(&out,
-			"// runtime·callbackasm is called by external code to\n"
-			"// execute Go implemented callback function. It is not\n"
-			"// called from the start, instead runtime·compilecallback\n"
-			"// always returns address into runtime·callbackasm offset\n"
-			"// appropriately so different callbacks start with different\n"
-			"// CALL instruction in runtime·callbackasm. This determines\n"
-			"// which Go callback function is executed later on.\n"
-			"TEXT runtime·callbackasm(SB),7,$0\n");
-		for(i=0; i<MAXWINCB; i++) {
-			bwritef(&out, "\tCALL\truntime·callbackasm1(SB)\n");
-		}
-		bwritef(&out, "\tRET\n");
-	}
-
-	writefile(&out, file, 0);
-	
-	bfree(&out);
-}
diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index 5dcaa04a1..58fc98d84 100644
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -813,7 +813,8 @@ func (b *builder) build(a *action) (err error) {
 	}
 
 	if a.p.Standard && a.p.ImportPath == "runtime" && buildContext.Compiler == "gc" &&
-		!hasString(a.p.SFiles, "zsys_"+buildContext.GOOS+"_"+buildContext.GOARCH+".s") {
+		(!hasString(a.p.GoFiles, "zgoos_"+buildContext.GOOS+".go") ||
+			!hasString(a.p.GoFiles, "zgoarch_"+buildContext.GOARCH+".go")) {
 		return fmt.Errorf("%s/%s must be bootstrapped using make%v", buildContext.GOOS, buildContext.GOARCH, defaultSuffix())
 	}