[Courgette] Make ELF section header sorting less intrusive.

[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also updated tests.

BUG=604542
Committed: https://crrev.com/691893008b56e5aea1fde29519988249b26de1c9
Cr-Commit-Position: refs/heads/master@{#388290}

[huangs, 2016-04-19 18:24:27]

huangs@chromium.org changed reviewers:
+ wfh@chromium.org

[huangs, 2016-04-19 18:24:27]

This bug indirectly blocks the 25% peak RAM reduction effort due to inconsistent
results for ARM x86 patching.  After this  there are a few more tasks:
- Extract section names for ARM.
- For ELF, only process ".text" section (otherwise we'd get bogus rel32
addresses that eat space).

PTAL.  Thanks!

[huangs, 2016-04-19 18:24:34]

The CQ bit was checked by huangs@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-04-19 18:25:07]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1900223002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1900223002/1

[Will Harris, 2016-04-19 18:33:19]

Description was changed from

==========
[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also udpated tests.

BUG=604542
==========

to

==========
[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also updated tests.

BUG=604542
==========

[Will Harris, 2016-04-19 18:36:35]

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
File courgette/disassembler_elf_32_x86_unittest.cc (right):

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
courgette/disassembler_elf_32_x86_unittest.cc:35:
EXPECT_EQ(static_cast<size_t>(SectionHeaderCount()), file_offsets.size());
brackets in wrong place?

[huangs, 2016-04-19 19:02:53]

PTAL.

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
File courgette/disassembler_elf_32_x86_unittest.cc (right):

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
courgette/disassembler_elf_32_x86_unittest.cc:35:
EXPECT_EQ(static_cast<size_t>(SectionHeaderCount()), file_offsets.size());
I looked carefully, looks alright.  static_cast<>() makes it look weird.

[commit-bot: I haz the power, 2016-04-19 19:25:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-19 19:25:06]

Dry run: This issue passed the CQ dry run.

[Will Harris, 2016-04-19 19:44:25]

lgtm

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
File courgette/disassembler_elf_32_x86_unittest.cc (right):

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
courgette/disassembler_elf_32_x86_unittest.cc:35:
EXPECT_EQ(static_cast<size_t>(SectionHeaderCount()), file_offsets.size());
On 2016/04/19 19:02:53, huangs wrote:
> I looked carefully, looks alright.  static_cast<>() makes it look weird.

ah yes you're right I was missing the close bracket.

[huangs, 2016-04-19 19:59:52]

Thanks.  Committing!

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
File courgette/disassembler_elf_32_x86_unittest.cc (right):

https://codereview.chromium.org/1900223002/diff/1/courgette/disassembler_elf_...
courgette/disassembler_elf_32_x86_unittest.cc:35:
EXPECT_EQ(static_cast<size_t>(SectionHeaderCount()), file_offsets.size());
On 2016/04/19 19:44:25, Will Harris wrote:
> On 2016/04/19 19:02:53, huangs wrote:
> > I looked carefully, looks alright.  static_cast<>() makes it look weird.
> 
> ah yes you're right I was missing the close bracket.

Acknowledged.

[huangs, 2016-04-19 19:59:59]

The CQ bit was checked by huangs@chromium.org

[commit-bot: I haz the power, 2016-04-19 20:00:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1900223002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1900223002/1

[commit-bot: I haz the power, 2016-04-19 20:04:46]

Description was changed from

==========
[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also updated tests.

BUG=604542
==========

to

==========
[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also updated tests.

BUG=604542
==========

[commit-bot: I haz the power, 2016-04-19 20:04:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-22 19:15:35]

Description was changed from

==========
[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also updated tests.

BUG=604542
==========

to

==========
[Courgette] Make ELF section header sorting less intrusive.

Recently we start to sort ELF section headers by file offset. However,
directly sorting the section headers is intrusive because it scrambles
section ids (order in array). This CL adds a layer of section id lookup,
so we can visit section headers in file offset order without affecting
section ids. Also updated tests.

BUG=604542

Committed: https://crrev.com/691893008b56e5aea1fde29519988249b26de1c9
Cr-Commit-Position: refs/heads/master@{#388290}
==========

[commit-bot: I haz the power, 2016-04-22 19:15:36]

Patchset 1 (id:??) landed as
https://crrev.com/691893008b56e5aea1fde29519988249b26de1c9
Cr-Commit-Position: refs/heads/master@{#388290}