cmd/link: external linker generates larger binaries than 6l/8l

[gopherbot]

by unclejacksons:

What steps will reproduce the problem?

Using 6l from Go 1.1:
go build -ldflags '-s -linkmode internal' -tags release
github.com/valyala/ybc/apps/go/memcached
wc -c memcached 
  1562016 memcached

Using Go 1.1 the patch which passes '-s' to ld:
go build -ldflags '-s' -tags release github.com/valyala/ybc/apps/go/memcached
wc -c memcached 
  2096920 memcached

Using Go 1.1 release:
wc -c memcached
  3194317 memcached

What is the expected output?
The resulting binary linked with the external linker should be smaller, its size should
be closer to that of the binary linked with 6l.
Since Go 1.1 defaults to using the external linker because it's more mature, it should
generate smaller binaries.


Which compiler are you using (5g, 6g, 8g, gccgo)?
6g

Which operating system are you using?
Ubuntu 13.04 amd64

Which version are you using?  (run 'go version')
go version go1.1 linux/amd64 from
https://go.googlecode.com/files/go1.1.linux-amd64.tar.gz


What can be done to make the resulting binaries smaller?

[robpike]

Comment 1:

For a simple case, external does generate a smaller binary:
% cat x.go
package main
import "fmt"
func main() {
    fmt.Printf("hello world\n")
}
% go build -ldflags '-linkmode internal'  x.go
% ls -l x
-rwxr-xr-x  1 r  staff  1525872 May 19 07:38 x
% x
hello world
% go build -ldflags '-linkmode external'  x.go
% ls -l x
-rwxr-xr-x  1 r  staff  1167348 May 19 07:38 x
% x
hello world
% 
So it's not so clear cut. (The -s flag produces similar ratios and slightly smaller
binaries but the programs don't run; that's a different issue.)

Labels changed: added priority-later, removed priority-triage.

Owner changed to @ianlancetaylor.

Status changed to Accepted.

[rsc]

Comment 2:

Labels changed: added go1.2maybe.

[rsc]

Comment 3:

Labels changed: added feature.

[robpike]

Comment 4:

Not for 1.2.

Labels changed: removed go1.2maybe.

[rsc]

Comment 5:

Labels changed: added go1.3maybe.

[rsc]

Comment 6:

Labels changed: removed feature.

[rsc]

Comment 7:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 8:

Labels changed: added repo-main.