code review 3002041: ld: fix dwarf decoding of 64-bit reflect values

ld: fix dwarf decoding of 64-bit reflect values

[ejsherry, 2010-11-09 13:50:02]

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

I'd like you to review this change.

[rsc, 2010-11-15 21:45:56]

LGTM

I think the shift might have been
equivalent except that it would be
wrong for 64-bit values because int is 32 bits.
Please change (uchar *) to (uchar*).

[rsc, 2010-11-15 21:46:42]

Please change the CL description to
something about the effect, like

ld: fix dwarf decoding of 64-bit reflect values

[ejsherry, 2010-11-16 04:23:19]

On 2010/11/15 21:45:56, rsc wrote:
> LGTM
> 
> I think the shift might have been
> equivalent except that it would be
> wrong for 64-bit values because int is 32 bits.

Shifting with an uvlong cast works on a little-ending host but not on a
big-endian one.

Unfortunately, inuxi8 is still wrong when building on a host that has the
opposite byte order of the target. That bug comes directly from the inferno
tools.

[ejsherry, 2010-11-16 04:26:48]

Hello rsc (cc: golang-dev@googlegroups.com),

Please take another look.

[rsc, 2010-11-16 12:55:46]

> Unfortunately, inuxi8 is still wrong when building on a host that has
> the opposite byte order of the target.

Why is that?  Why is it different from inuxi4?

Russ

[ejsherry, 2010-11-16 15:04:43]

On 16 November 2010 04:55, Russ Cox <rsc@golang.org> wrote:
>> Unfortunately, inuxi8 is still wrong when building on a host that has
>> the opposite byte order of the target.
>
> Why is that?  Why is it different from inuxi4?

Inuxi8 is initialised as the catenation of inuxi4 and inuxi4+4. So on
a little-endian host we get,

inuxi4=0123
inuxi8=01234567

which is right, but on a big-endian host it's,

inuxi4=3210
inuxi8=32107654

As far as I can tell inuxi8 should be 76543210 on a big-endian.

About to do a PTAL with it fixed. It's ugly though.

Going in a different direction, maybe the nuxi stuff should be
replaced by the corresponding get and put byte packing functions. Nuxi
is only used in a couple of places (and only in ld).

Eoghan

[ejsherry, 2010-11-16 15:07:14]

Hello rsc (cc: golang-dev@googlegroups.com),

Please take another look.

[rsc, 2010-12-07 17:53:28]

LGTM

But it no longer applies to the current tree.
Please hg sync + hg mail 3002041
Thanks

[ejsherry, 2010-12-07 22:13:55]

Hello rsc (cc: golang-dev@googlegroups.com),

Please take another look.

[rsc, 2010-12-07 22:20:54]

*** Submitted as 9f00af1edd70 ***

ld: fix dwarf decoding of 64-bit reflect values

R=rsc
CC=golang-dev
http://codereview.appspot.com/3002041

Committer: Russ Cox <rsc@golang.org>