cmd/ld: correct addresses in windows pe symbol table

This should have been part of 36eb4a62fbb6,
but I later discovered that addresses are all wrong.
Appropriate test added now.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/89470043

src/cmd/ld/pe.c

@@ -509,6 +509,17 @@ addsym(LSym *s, char *name, int type, vlong addr, vlong size, int ver, LSym *got
 	ncoffsym++;
 }
 
+static vlong
+datoffsect(vlong addr)
+{
+	if(addr >= segdata.vaddr)
+		return addr - segdata.vaddr;
+	if(addr >= segtext.vaddr)
+		return addr - segtext.vaddr;
+	diag("datoff %#llx", addr);
+	return 0;
+}
+
 static void
 addsymtable(void)
 {
@@ -540,7 +551,7 @@ addsymtable(void)
 			lputl(0);
 			lputl(s->strtbloff);
 		}
-		lputl(datoff(s->sym->value));
+		lputl(datoffsect(s->sym->value));
 		wputl(s->sect);
 		wputl(0x0308);  // "array of structs"
 		cput(2);        // storage class: external

src/cmd/nm/nm_test.go

@@ -5,13 +5,55 @@
 package main
 
 import (
+	"bufio"
+	"bytes"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 )
 
+var testData uint32
+
+func checkSymbols(t *testing.T, nmoutput []byte) {
+	var checkSymbolsFound, testDataFound bool
+	scanner := bufio.NewScanner(bytes.NewBuffer(nmoutput))
+	for scanner.Scan() {
+		f := strings.Fields(scanner.Text())
+		if len(f) < 3 {
+			t.Error("nm must have at least 3 columns")
+			continue
+		}
+		switch f[2] {
+		case "cmd/nm.checkSymbols":
+			checkSymbolsFound = true
+			addr := "0x" + f[0]
+			if addr != fmt.Sprintf("%p", checkSymbols) {
+				t.Errorf("nm shows wrong address %v for checkSymbols (%p)", addr, checkSymbols)
+			}
+		case "cmd/nm.testData":
+			testDataFound = true
+			addr := "0x" + f[0]
+			if addr != fmt.Sprintf("%p", &testData) {
+				t.Errorf("nm shows wrong address %v for testData (%p)", addr, &testData)
+			}
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		t.Errorf("error while reading symbols: %v", err)
+		return
+	}
+	if !checkSymbolsFound {
+		t.Error("nm shows no checkSymbols symbol")
+	}
+	if !testDataFound {
+		t.Error("nm shows no testData symbol")
+	}
+}
+
 func TestNM(t *testing.T) {
 	out, err := exec.Command("go", "build", "-o", "testnm.exe", "cmd/nm").CombinedOutput()
 	if err != nil {
@@ -37,4 +79,11 @@ func TestNM(t *testing.T) {
 			t.Fatalf("go tool nm %v: %v\n%s", exepath, err, string(out))
 		}
 	}
+
+	cmd := exec.Command("./testnm.exe", os.Args[0])
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("go tool nm %v: %v\n%s", os.Args[0], err, string(out))
+	}
+	checkSymbols(t, out)
 }