cmd/nm: print symbol sizes for windows pe executables

Fixes #6973

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/88820043

src/cmd/nm/pe.go

@@ -9,6 +9,7 @@ package main
 import (
 	"debug/pe"
 	"os"
+	"sort"
 )
 
 func peSymbols(f *os.File) []Sym {
@@ -18,6 +19,10 @@ func peSymbols(f *os.File) []Sym {
 		return nil
 	}
 
+	// Build sorted list of addresses of all symbols.
+	// We infer the size of a symbol by looking at where the next symbol begins.
+	var addrs []uint64
+
 	var imageBase uint64
 	switch oh := p.OptionalHeader.(type) {
 	case *pe.OptionalHeader32:
@@ -78,6 +83,15 @@ func peSymbols(f *os.File) []Sym {
 			sym.Addr += imageBase + uint64(sect.VirtualAddress)
 		}
 		syms = append(syms, sym)
+		addrs = append(addrs, sym.Addr)
+	}
+
+	sort.Sort(uint64s(addrs))
+	for i := range syms {
+		j := sort.Search(len(addrs), func(x int) bool { return addrs[x] > syms[i].Addr })
+		if j < len(addrs) {
+			syms[i].Size = int64(addrs[j] - syms[i].Addr)
+		}
 	}
 
 	return syms

src/pkg/runtime/arch_amd64.h

@@ -8,9 +8,13 @@ enum {
 	CacheLineSize = 64,
 #ifdef GOOS_solaris
 	RuntimeGogoBytes = 80,
+#else
+#ifdef GOOS_windows
+	RuntimeGogoBytes = 80,
 #else
 	RuntimeGogoBytes = 64,
-#endif
+#endif	// Windows
+#endif	// Solaris
 	PhysPageSize = 4096,
 	PCQuantum = 1
 };

src/pkg/runtime/runtime_test.go

@@ -95,10 +95,6 @@ func BenchmarkDeferMany(b *testing.B) {
 // The value reported will include the padding between runtime.gogo and the
 // next function in memory. That's fine.
 func TestRuntimeGogoBytes(t *testing.T) {
-	// TODO(brainman): delete when issue 6973 is fixed.
-	if GOOS == "windows" {
-		t.Skip("skipping broken test on windows")
-	}
 	dir, err := ioutil.TempDir("", "go-build")
 	if err != nil {
 		t.Fatalf("failed to create temp directory: %v", err)