Commit Graph

230 Commits

Author SHA1 Message Date
Rafael Espindola a6acd23c53 Align addresses, not offsets.
This fixes two more cases where we were aligning the offset in a
section, instead of the final address.

llvm-svn: 312983
2017-09-12 00:06:00 +00:00
George Rimar 5f37541c73 [ELF] - Linkerscript: implement REGION_ALIAS.
REGION_ALIAS(alias, region)

Alias names can be added to existing memory regions created with
the MEMORY command. Each name corresponds to at most one
memory region.

Differential revision: https://reviews.llvm.org/D37477

llvm-svn: 312777
2017-09-08 08:23:15 +00:00
Rafael Espindola 8c022ca783 Merge OutputSectionCommand and OutputSection.
This is a bit of a hack, but it is *so* convenient.

Now that we create synthetic linker scripts when none is provided, we
always have to handle paired OutputSection and OutputsectionCommand and
keep a mapping from one to the other.

This patch simplifies things by merging them and creating what used to
be OutputSectionCommands really early.

llvm-svn: 309311
2017-07-27 19:22:43 +00:00
George Rimar aa3541875e [ELF] - Store PhdrEntry values by pointers instead of storing by value.
That is slightly more convinent as allows to store pointer on
program header entry in a more safe way.
 
Change was used in 2 patches currently on review.

Differential revision: https://reviews.llvm.org/D35832

llvm-svn: 309253
2017-07-27 07:46:50 +00:00
Petr Hosek 8b591f592b [ELF] Remove processNonSectionCommands
This method is no longer being used anywhere.

Differential Revision: https://reviews.llvm.org/D35706

llvm-svn: 308706
2017-07-21 01:02:30 +00:00
Peter Smith 906e9a1898 [ELF] Extract temporary state used in assignAddresses()
The assignAddresses() function accumulates state in the LinkerScript that
prevents it from being called multiple times. This change moves the state
into a separate structure AddressState that is created at the start of the
function and disposed of at the end.

CurAddressState is used rather than passing a reference to the state as a
parameter to the functions used by assignAddresses(). This is because the
getSymbolValue function needs to be executed in the context of AddressState
but it is stored in ScriptParser when AddressState is not available.

The AddressState is also used in a limited context by processCommands()

Differential Revision: https://reviews.llvm.org/D34345

llvm-svn: 307367
2017-07-07 09:11:27 +00:00
Rafael Espindola 2126334e08 Move fabricateDefaultCommands earlier.
It is now just after the OutputSections are created, which is as early
as it can possibly go.

llvm-svn: 307225
2017-07-05 23:36:24 +00:00
Rafael Espindola 9f9e99be20 Simplify. NFC.
llvm-svn: 307217
2017-07-05 22:30:04 +00:00
Rafael Espindola cf7347379f Remove a function that is now trivial.
llvm-svn: 307214
2017-07-05 22:25:38 +00:00
Rafael Espindola d7faa9165f Merge createOrphanCommands into addOrphanSections.
This is a bit simpler and avoids a walk over OutputSections.

llvm-svn: 307178
2017-07-05 17:50:43 +00:00
Peter Smith 5aedebff38 [ELF] Extract allocateHeaders() from assignAddresses()
The allocateHeaders() function is called at the end of assignAddresses(), it
decides whether the ELF header and program header table can be allocated to
a PT_LOAD program header. As the function alters state, it prevents
assignAddresses() from being called multiple times.

This change splits out the call to allocateHeaders() from assignAddresses()
this will permit assignAddresses() to be called while processing range
extension thunks without trying to allocateHeaders().

Differential Revision: https://reviews.llvm.org/D34344

llvm-svn: 307131
2017-07-05 09:12:54 +00:00
Rafael Espindola 383971d2a7 Move clearOutputSections before sortSections.
This is probably the main patch left in unifying our intermediary
representation.

It moves the creation of default commands before section sorting. This
has the nice effect that we now have one location where we decide
where an orphan section should be placed.

Before this patch sortSections would decide the relative location of
orphan sections to other sections, but it was up to placeOrphanSection
to decide on the exact location.

We now only sort sections we created since the linker script is
already in the correct order.

llvm-svn: 305512
2017-06-15 21:51:01 +00:00
Rafael Espindola f51c80559c Make OutputSections and OutputSectionCommands globals.
This is similar to what we do for InputSections and makes them easier
to access.

llvm-svn: 305337
2017-06-13 23:26:31 +00:00
Rafael Espindola 7ff9329b7c Move clearOutputSections before createPhdrs. NFC.
llvm-svn: 305156
2017-06-10 22:12:32 +00:00
George Rimar fbb0463f39 [ELF] - Linkerscript: implement NOLOAD section type.
This is PR32351

Each output section may have a type. The type is a keyword in parentheses.
(https://sourceware.org/binutils/docs/ld/Output-Section-Type.html#Output-Section-Type)
This patch support only one type, it is NOLOAD.
If output section has such type, we force it to be SHT_NOBITS. 

More details are available on a review page.

Differential revision: https://reviews.llvm.org/D33647

llvm-svn: 304925
2017-06-07 16:31:08 +00:00
Peter Smith 8e791463ef [ELF] Convert Thunks to use InputSectionDescriptions
Thunks are now generated per InputSectionDescription instead of per
OutputSection. This allows created ThunkSections to be inserted directly
into InputSectionDescription.

Changes in this patch:
- Loop over InputSectionDescriptions to find relocations to Thunks
- Generate a ThunkSection per InputSectionDescription
- Remove synchronize() as we no longer need it
- Move fabricateDefaultCommands() before createThunks

Differential Revision: https://reviews.llvm.org/D33835

llvm-svn: 304887
2017-06-07 09:35:14 +00:00
George Rimar 41c7ab4a3d [ELF] - Linkerscript: improved error reporting.
When linking linux kernel LLD currently reports next errors:

ld: error: unable to evaluate expression: input section .head.text has no output section assigned
ld: error: At least one side of the expression must be absolute
ld: error: At least one side of the expression must be absolute

That does not provide file/line information and overall looks unclear. 
Patch adds location information to ExprValue and that allows
to provide more clear error messages.

Differential revision: https://reviews.llvm.org/D33943

llvm-svn: 304881
2017-06-07 08:54:43 +00:00
Rafael Espindola 8c284acf14 Move finalize to OutputSectionCommands. NFC.
This removes a mapping from OutputSection to OutputSectionCommand and
is another step in moving clearOutputSections earlier.

llvm-svn: 304821
2017-06-06 19:40:01 +00:00
Rafael Espindola 6888072808 Move maybeCompress to OutputSectionCommand.
This removes a call to getCmd and allows us to move
clearOutputSections earlier.

llvm-svn: 304439
2017-06-01 16:57:48 +00:00
Rafael Espindola faf25a7216 Convert a few more uses of OutputSections. NFC.
Also needed to move clearOutputSections earlier.

llvm-svn: 304420
2017-06-01 16:26:28 +00:00
Rafael Espindola 05c4f67cf3 Move name lookup to script parsing time.
We were looking up sections by name during expression evaluation. By
keeping track of forward declarations we can do the lookup during
script parsing.

Doing the lookup earlier will be more efficient when assignAddresses
is run twice and removes two uses of OutputSections.

llvm-svn: 304381
2017-06-01 01:16:50 +00:00
Petr Hosek 3c6de1a66c [ELF] Use late evaluation for ALIGN in expression
While the following expression is handled fine:

  PROVIDE_HIDDEN(newsym = oldsym + address);

The following expression triggers an error because the expression
is evaluated as absolute:

  PROVIDE_HIDDEN(newsym = ALIGN(oldsym, CONSTANT(MAXPAGESIZE)) + address);

To avoid this error, we use late evaluation for ALIGN by making the
alignment an attribute of the expression itself.

Differential Revision: https://reviews.llvm.org/D33629

llvm-svn: 304185
2017-05-30 03:18:28 +00:00
Rafael Espindola 55b169bf5d Move writeTo to OutputSectionCommand.
This reduces how many times we have to map from OutputSection to
OutputSectionCommand. It is a required step to moving
clearOutputSections earlier.

In order to always use writeTo in OutputSectionCommand we have to call
fabricateDefaultCommands for -r links and move section compression
after it.

llvm-svn: 303784
2017-05-24 18:08:04 +00:00
Rafael Espindola 6a1aa8d9b4 Use more strict types. NFC.
By the time we get to linker scripts, all special InputSectionBase
should have been combined into synthetic sections, which are a type of
InputSection. The net result is that we can use InputSection in a few
places that were using InputSectionBase.

llvm-svn: 303702
2017-05-23 22:47:31 +00:00
Rafael Espindola d7dc225888 Use a DenseMap in LinkerScript::getCmd.
This improves many-sections.s with a linker script from 22s to 0.9s.

llvm-svn: 302708
2017-05-10 19:13:38 +00:00
Rafael Espindola fa948c724a Refactor OutputSection to OutputSectionCommand mapping.
We now always use getCmd. I will optimize it in a followup commit.

llvm-svn: 302706
2017-05-10 19:00:23 +00:00
Rafael Espindola c2dd0bdf17 Mark LinkerScript as final.
We used to inherit from it, but don't need it anymore.

llvm-svn: 302675
2017-05-10 14:45:15 +00:00
Rafael Espindola 2c923c2c37 Remove another use of section names. NFC.
llvm-svn: 302671
2017-05-10 14:28:31 +00:00
Rafael Espindola dc1ed12015 Remove another use of section names. NFC.
llvm-svn: 302662
2017-05-10 14:12:02 +00:00
Rafael Espindola c5b612b8b4 Don't use section names in getFiller. NFC.
This is just faster and avoids using names.

llvm-svn: 302661
2017-05-10 14:01:13 +00:00
Rafael Espindola 660c9ab929 Delete LinkerScript::getSectionIndex.
We can set SectionIndex tentatively as we process the linker script
instead of looking it repeatedly.

In general we should try to have as few name lookups as possible.

llvm-svn: 302299
2017-05-05 21:34:26 +00:00
Rafael Espindola 02ed7575e7 Simplify the header allocation.
In the non linker script case we would try very early to find out if
we could allocate the headers. Failing to do that would add extra
alignment to the first ro section, since we would set PageAlign
thinking it was the first section in the PT_LOAD.

In the linker script case the header allocation must be done in the
end, causing some duplication.

We now tentatively add the headers to the first PT_LOAD and if it
turns out they don't fit, remove them. With this we only need to
allocate the headers in one place in the code.

llvm-svn: 302186
2017-05-04 19:34:17 +00:00
Rafael Espindola 7c4eafa3ee Fix accounting of tbss.
We were correctly computing the size contribution of a .tbss input
section (it is none), but we were incorrectly considering the
alignment of the output section: it was advancing Dot instead of
ThreadBssOffset.

As far as I can tell this was always wrong in our linkerscript
implementation, but that became more visible now that the code is
shared with the non linker script case.

llvm-svn: 302107
2017-05-04 03:00:27 +00:00
Rafael Espindola de8d9897d9 Bring back r301678.
This version uses a set to speed up the synchronize method.

Original message:

    Remove LinkerScript::flush.

    This patch replaces flush with a last ditch attempt at synchronizing
    the section list with the linker script "AST".

    The synchronization is a bit of a hack and should in time be avoided
    by creating the AST earlier so that modifications can be made directly
    to it instead of modifying the section list and synchronizing it back.

    This is the main step for fixing
    https://bugs.llvm.org/show_bug.cgi?id=32816. With this in place I
    think the only missing thing would be to have processCommands assign
    section indexes as dummy offsets so that the sort in
    OutputSection::finalize works.

    With this LinkerScript::assignAddresses becomes much simpler, which
    should help with the thunk work.

llvm-svn: 301745
2017-04-29 15:44:03 +00:00
Rui Ueyama 216aa11cc5 Revert r301678: Remove LinkerScript::flush.
This reverts commit r301678 since that change significantly slowed
down the linker. Before this patch, LLD could link clang in 8 seconds,
but with this patch it took 40 seconds.

llvm-svn: 301709
2017-04-28 22:40:58 +00:00
Rafael Espindola b3bc1ed0d4 Remove LinkerScript::flush.
This patch replaces flush with a last ditch attempt at synchronizing
the section list with the linker script "AST".

The synchronization is a bit of a hack and should in time be avoided
by creating the AST earlier so that modifications can be made directly
to it instead of modifying the section list and synchronizing it back.

This is the main step for fixing
https://bugs.llvm.org/show_bug.cgi?id=32816. With this in place I
think the only missing thing would be to have processCommands assign
section indexes as dummy offsets so that the sort in
OutputSection::finalize works.

With this LinkerScript::assignAddresses becomes much simpler, which
should help with the thunk work.

llvm-svn: 301678
2017-04-28 20:22:47 +00:00
Peter Smith cbfe9e946f [ELF] Always use Script::assignAddresses()
This change fabricates linker script commands for the case where there is
no linker script SECTIONS to control address assignment. This permits us
to have a single Script->assignAddresses() function.
    
There is a small change in user-visible-behavior with respect to the
handling of .tbss SHT_NOBITS, SHF_TLS as the Script->assignAddresses()
requires setDot() to be called with monotically increasing addresses.
The tls-offset.s test has been updated so that the script and non-script
results match.

This change should make the non-script behavior of lld closer to an
equivalent linker script.

Differential Revision: https://reviews.llvm.org/D31888

llvm-svn: 300687
2017-04-19 12:46:32 +00:00
James Henderson 9d9a663731 [ELF] Recommit r299635 to pad x86 executable sections with 0xcc
This follows r299748 which fixed a latent bug the original commit exposed.

llvm-svn: 299755
2017-04-07 10:36:42 +00:00
Rafael Espindola feed750676 Move call to findMemoryRegion before assignAddresses.
This removes a bit more work from assignAddresses.

llvm-svn: 299716
2017-04-06 21:31:24 +00:00
Rafael Espindola 1902b337e9 Remove redundant argument. NFC.
llvm-svn: 299713
2017-04-06 21:26:03 +00:00
Rafael Espindola 9b9800951d Cache the result of findSection.
This avoids calling it multiple times. In particular, we don't have to
call in in assignAddresses any more.

llvm-svn: 299709
2017-04-06 21:05:39 +00:00
James Henderson d983180778 Revert r299635 because it exposed a latent bug.
llvm-svn: 299655
2017-04-06 15:22:58 +00:00
James Henderson 8dd4c06a77 [ELF] Pad x86 executable sections with 0xcc int3 instructions
Executable sections should not be padded with zero by default. On some
architectures, 0x00 is the start of a valid instruction sequence, so can confuse
disassembly between InputSections (and indeed the start of the next InputSection
in some situations). Further, in the case of misjumps into padding, padding may
start to be executed silently.

On x86, the "0xcc" byte represents the int3 trap instruction. It is a single
byte long so can serve well as padding. This change switches x86 (and x86_64) to
use this value for padding in executable sections, if no linker script directive
overrides it. It also puts the behaviour into place making it easy to change the
behaviour of other targets when desired. I do not know the relevant instruction
sequences for trap instructions on other targets however, so somebody should add
this separately.

Because the old behaviour simply wrote padding in the whole section before
overwriting most of it, this change also modifies the padding algorithm to write
padding only where needed. This in turn has caused a small behaviour change with
regards to what values are written via Fill commands in linker scripts, bringing
it into line with ld.bfd. The fill value is now written starting from the end of
the previous block, which means that it always starts from the first byte of the
fill, whereas the old behaviour meant that the padding sometimes started mid-way
through the fill value. See the test changes for more details.

Reviewed by: ruiu

Differential Revision: https://reviews.llvm.org/D30886

Bugzilla: http://bugs.llvm.org/show_bug.cgi?id=32227
llvm-svn: 299635
2017-04-06 09:29:08 +00:00
Rui Ueyama 63fda39e2f Remove unnecessary virtual dtor.
This class doesn't have virtual member functions, and no instances
of this class is deleted through base pointers.

llvm-svn: 299581
2017-04-05 19:21:35 +00:00
Rui Ueyama 03fc8d1e0d Fix comments.
llvm-svn: 299579
2017-04-05 19:20:54 +00:00
Rui Ueyama 4eb2eccb24 Rename ScriptConfig::UndefinedSymbols ReferencedSymbols.
Symbols referenced by linker scripts are not necessarily be undefined,
so the previous name didn't convey the meaining of the variable.

llvm-svn: 299573
2017-04-05 18:02:30 +00:00
Rui Ueyama 96b3fe025a Do not make ScriptParser class public.
This class is used only within this file, so it can be file-local.

llvm-svn: 299516
2017-04-05 05:08:01 +00:00
Rui Ueyama 2ec34544aa Move the parser for the linker script to a separate file.
LinkerScript.cpp contains both the linker script processor and the
linker script parser. I put both into a single file, but the file grown
too large, so it's time to put them into two different files.

llvm-svn: 299515
2017-04-05 05:07:39 +00:00
Rui Ueyama 8f99f73c8f Use make to create linker script command objects.
It simplifies variable types.

llvm-svn: 299505
2017-04-05 03:20:42 +00:00
Rui Ueyama d379f7357d Remove default arguments because they don't improve readability.
llvm-svn: 299504
2017-04-05 03:20:22 +00:00