TickProcessor: more accurate mapping of statically compiled code on Linux.

TickProcessor: more accurate mapping of statically compiled code on Linux.

'nm' is now called with an option to report function code sizes. Static code entries are restricted to the sizes reported, and the remaining unnamed code is attributed to a library as a whole. This makes reports more accurate, as some functions are tiny, but has chunks of unnamed code behind them.

This change doesn't affect reporting on Windows, as in .map files function code sizes aren't specified.

Committed: http://code.google.com/p/v8/source/detail?r=2455

[Mikhail Naganov, 2009-07-12 14:57:49]

Hi Erik,

This is the change that we've discussed some time ago. Dean had pointed out that
when calling 'exp' library function, many ticks are assigned to 'fegetexcept'
function which isn't really called. This was due to a fact that 'fegetexcept'
itself is tiny but under it there is a big chunk of unnamed code, that owned
reported PC values.

Now such executions of unnamed code are attributed to a library itself.

[Mikhail Naganov, 2009-07-14 07:33:01]

Adding Kasper as Erik is on vacation.

[Kasper Lund, 2009-07-14 07:52:57]

LGTM.

http://codereview.chromium.org/149513/diff/1/10
File tools/tickprocessor.js (right):

http://codereview.chromium.org/149513/diff/1/10#newcode387
Line 387: if (prevEntry && !('end' in prevEntry) &&
The 'end' in prevEntry stuff looks a bit weird to me. I think it would be more
common just to use prevEntry.end, unless you worry about it being zero.

http://codereview.chromium.org/149513/diff/1/10#newcode410
Line 410: if ('size' in funcInfo) {
Is this because you worry that size can be zero?

[Mikhail Naganov, 2009-07-14 09:45:47]

Thanks, Kasper!

http://codereview.chromium.org/149513/diff/1/10
File tools/tickprocessor.js (right):

http://codereview.chromium.org/149513/diff/1/10#newcode387
Line 387: if (prevEntry && !('end' in prevEntry) &&
On 2009/07/14 07:52:57, Kasper Lund wrote:
> The 'end' in prevEntry stuff looks a bit weird to me. I think it would be more
> common just to use prevEntry.end, unless you worry about it being zero.

You're right, zero is a forbidden value here. Changed to value check.

http://codereview.chromium.org/149513/diff/1/10#newcode410
Line 410: if ('size' in funcInfo) {
On 2009/07/14 07:52:57, Kasper Lund wrote:
> Is this because you worry that size can be zero?

Done.