code review 65890043: cmd/go: skip writing dwarf debug info for ephemeral binaries

cmd/go: skip writing dwarf debug info for ephemeral binaries

Update issue 6853

For an ephemeral binary - one created, run, and then deleted -
there is no need to write dwarf debug information, since the
binary will not be used with gdb. In this case, instruct the linker
not to spend time and disk space generating the debug information
by passing the -w flag to the linker.

Omitting dwarf information reduces the size of most binaries by 25%.
We may be more aggressive about this in the future.

[rsc, 2014-02-19 04:50:36]

Hello r (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[bradfitz, 2014-02-19 04:55:16]

https://codereview.appspot.com/65890043/diff/20001/src/cmd/go/test.go
File src/cmd/go/test.go (right):

https://codereview.appspot.com/65890043/diff/20001/src/cmd/go/test.go#newcode657
src/cmd/go/test.go:657: omitDWARF:  !testC,
does this include the implicit testC that's enabled by profiling?

[rsc, 2014-02-19 05:04:16]

https://codereview.appspot.com/65890043/diff/20001/src/cmd/go/test.go
File src/cmd/go/test.go (right):

https://codereview.appspot.com/65890043/diff/20001/src/cmd/go/test.go#newcode657
src/cmd/go/test.go:657: omitDWARF:  !testC,
On 2014/02/19 04:55:16, bradfitz wrote:
> does this include the implicit testC that's enabled by profiling?

No. Fixed.

[bradfitz, 2014-02-19 05:07:47]

LGTM

[rsc, 2014-02-19 05:11:17]

I added test/run.go to this CL.

[bradfitz, 2014-02-19 05:12:02]

Still uploading?

[rsc, 2014-02-19 05:13:53]

uploaded

[bradfitz, 2014-02-19 05:15:43]

LGTM

[r, 2014-02-19 06:36:23]

LGTM

maybe updates 6853 again?

[rsc, 2014-02-19 15:01:17]

*** Submitted as https://code.google.com/p/go/source/detail?r=306e64f0c0cf ***

cmd/go: skip writing dwarf debug info for ephemeral binaries

Update issue 6853

For an ephemeral binary - one created, run, and then deleted -
there is no need to write dwarf debug information, since the
binary will not be used with gdb. In this case, instruct the linker
not to spend time and disk space generating the debug information
by passing the -w flag to the linker.

Omitting dwarf information reduces the size of most binaries by 25%.
We may be more aggressive about this in the future.

LGTM=bradfitz, r
R=r, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/65890043