This seems to have been a cargo-culted habit from the very first such
cache which didn't have any specific justification (but might've been a
layering constraint at the time).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206003 91177308-0d34-0410-b5e6-96231b3b80d8
To support compressing the debug_line section that contains multiple
fragments (due, I believe, to variation in choices of line table
encoding depending on the size of instruction ranges in the actual
program code) we needed to support compressing multiple MCFragments in a
single pass.
This patch implements that behavior by mutating the post-relaxed and
relocated section to be the compressed form of its former self,
including renaming the section.
This is a more flexible (and less invasive, to a degree) implementation
that will allow for other features such as "use compression only if it's
smaller than the uncompressed data".
Compressing debug_frame would be a possible further extension to this
work, but I've left it for now. The hurdle there is alignment sections -
which might require going as far as to refactor
MCAssembler.cpp:writeFragment to handle writing to a byte buffer or an
MCObjectWriter (there's already a virtual call there, so it shouldn't
add substantial compile-time cost) which could in turn involve
refactoring MCAsmBackend::writeNopData to use that same abstraction...
which involves touching all the backends. This would remove the limited
handling of fragment writing seen in
ELFObjectWriter.cpp:getUncompressedData which would be nice - but it's
more invasive.
I did discover that I (perhaps obviously) don't need to handle
relocations when I rewrite the fragments - since the relocations have
already been applied and computed (and stored into
ELFObjectWriter::Relocations) by this stage (necessarily, because we
need to have written any immediate values or assembly-time relocations
into the data already before we compress it, which we have). The test
case doesn't necessarily cover that in detail - I can add more test
coverage if that's preferred.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205990 91177308-0d34-0410-b5e6-96231b3b80d8
To support compression for debug_line and debug_frame a different
approach is required. To simplify review, revert the old implementation
and XFAIL the test case. New implementation to follow shortly.
Reverts r205059 and r204958.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205989 91177308-0d34-0410-b5e6-96231b3b80d8
Introduce ScalarTraits::mustQuote which determines whether or not a
StringRef needs quoting before it is acceptable to output.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205955 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Local common symbols were properly inserted into the .bss section.
However, putting external common symbols in the .bss section would give
them a strong definition.
Instead, encode them as undefined, external symbols who's symbol value
is equivalent to their size.
Reviewers: Bigcheese, rafael, rnk
CC: llvm-commits
Differential Revision: http://reviews.llvm.org/D3324
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205811 91177308-0d34-0410-b5e6-96231b3b80d8
This moves one case of raw text checking down into the MCStreamer
interfaces in the form of a virtual function, even if we ultimately end
up consolidating on the one-or-many line tables issue one day, this is
nicer in the interim. This just generally streamlines a bunch of use
cases into a common code path.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205287 91177308-0d34-0410-b5e6-96231b3b80d8
I don't think this is reachable by any frontend (why would you transform
asm to asm+debug info?) but it helps tidy up some of this code, avoid
the weird special case of "emit the first CU, store the label, then emit
the rest" in MCDwarfLineTable::Emit by instead having the
DWARF-for-assembly case use the same codepath as DwarfDebug.cpp, by
registering the label of the debug_line section, thus causing it to be
emitted. (with a special case in asm output to just emit the label since
asm output uses the .loc directives, etc, rather than the debug_loc
directly)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205286 91177308-0d34-0410-b5e6-96231b3b80d8
The ARM64 backend uses it only as a container to keep an MCLOHType and
Arguments around so give it its own little copy. The other functionality
isn't used and we had a crazy method specialization hack in place to
keep it working. Unfortunately that was incompatible with MSVC.
Also range-ify a couple of loops while at it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205114 91177308-0d34-0410-b5e6-96231b3b80d8
This adds a second implementation of the AArch64 architecture to LLVM,
accessible in parallel via the "arm64" triple. The plan over the
coming weeks & months is to merge the two into a single backend,
during which time thorough code review should naturally occur.
Everything will be easier with the target in-tree though, hence this
commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205090 91177308-0d34-0410-b5e6-96231b3b80d8
ARM64 has compact-unwind information, but doesn't necessarily want to
emit .eh_frame directives as well. This teaches MC about such a
situation so that it will skip .eh_frame info when compact unwind has
been successfully produced.
For functions incompatible with compact unwind, the normal information
is still written.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205087 91177308-0d34-0410-b5e6-96231b3b80d8
This is principally to allow neater mapping of fixups to relocations
in ARM64 ELF. Without this, there isn't enough information available
to GetRelocType, leading to many more fixup_arm64_... enumerators.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205085 91177308-0d34-0410-b5e6-96231b3b80d8
Another part of the ARM64 backend (so tests will be following soon).
This is currently used by the linker to relax adrp/ldr pairs into nops
where possible, though could well be more broadly applicable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205084 91177308-0d34-0410-b5e6-96231b3b80d8
The upcoming ARM64 backend doesn't have section-relative relocations,
so we give each section its own symbol to provide this functionality.
Of course, it doesn't need to appear in the final executable, so
linker-private is the best kind for this purpose.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205081 91177308-0d34-0410-b5e6-96231b3b80d8
I started trying to fix a small issue, but this code has seen a small fix too
many.
The old code was fairly convoluted. Some of the issues it had:
* It failed to check if a symbol difference was in the some section when
converting a relocation to pcrel.
* It failed to check if the relocation was already pcrel.
* The pcrel value computation was wrong in some cases (relocation-pc.s)
* It was missing quiet a few cases where it should not convert symbol
relocations to section relocations, leaving the backends to patch it up.
* It would not propagate the fact that it had changed a relocation to pcrel,
requiring a quiet nasty work around in ARM.
* It was missing comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205076 91177308-0d34-0410-b5e6-96231b3b80d8
Turns out debug_frame does use multiple fragments, so it doesn't
compress correctly with the current approach. Disable compressing it for
now while I figure out what's the best solution for it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205059 91177308-0d34-0410-b5e6-96231b3b80d8
Construct a uniform Windows target triple nomenclature which is congruent to the
Linux counterpart. The old triples are normalised to the new canonical form.
This cleans up the long-standing issue of odd naming for various Windows
environments.
There are four different environments on Windows:
MSVC: The MS ABI, MSVCRT environment as defined by Microsoft
GNU: The MinGW32/MinGW32-W64 environment which uses MSVCRT and auxiliary libraries
Itanium: The MSVCRT environment + libc++ built with Itanium ABI
Cygnus: The Cygwin environment which uses custom libraries for everything
The following spellings are now written as:
i686-pc-win32 => i686-pc-windows-msvc
i686-pc-mingw32 => i686-pc-windows-gnu
i686-pc-cygwin => i686-pc-windows-cygnus
This should be sufficiently flexible to allow us to target other windows
environments in the future as necessary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204977 91177308-0d34-0410-b5e6-96231b3b80d8
1) When creating a .debug_* section and instead create a .zdebug_
section.
2) When creating a fragment in a .zdebug_* section, make it a compressed
fragment.
3) When computing the size of a compressed section, compress the data
and use the size of the compressed data.
4) Emit the compressed bytes.
Also, check that only if a section has a compressed fragment, then that
is the only fragment in the section.
Assert-fail if the fragment's data is modified after it is compressed.
Initial review on llvm-commits by Eric Christopher and Rafael Espindola.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204958 91177308-0d34-0410-b5e6-96231b3b80d8
Allows this test to pass on COFF platforms so we don't need to restrict
this test to a single target anymore.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204780 91177308-0d34-0410-b5e6-96231b3b80d8
The logic was incorrect for variables, causing them to end up in the wrong
section if the section had an index >= 0xff00.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204771 91177308-0d34-0410-b5e6-96231b3b80d8
We need .symtab_shndxr if and only if a symbol references a section with an
index >= 0xff00.
The old code was trying to figure out if the section was needed ahead of time,
making it a fairly dependent on the code actually writing the table. It was
also somewhat conservative and would create the section in cases where it was
not needed.
If I remember correctly, the old structure was there so that the sections were
created in the same order gas creates them. That was valuable when MC's support
for ELF was new and we tested with elf-dump.py.
This patch refactors the symbol table creation to another class and makes it
obvious that .symtab_shndxr is really only created when we are about to output
a reference to a section index >= 0xff00.
While here, also improve the tests to use macros. One file is one section
short of needing .symtab_shndxr, the second one has just the right number.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204769 91177308-0d34-0410-b5e6-96231b3b80d8
While at it, factor some logic into FragmentWriter. This will allow more code
to be factored out of the fairly large ELFObjectWriter.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204765 91177308-0d34-0410-b5e6-96231b3b80d8
This is similar, but not identical to what gas does. The logic in MC is to just
compute the symbol table after parsing the entire file. GAS is mixed, given
.type b, @object
a = b
b:
.type b, @function
It will propagate the change and make 'a' a function. Given
.type b, @object
b:
a = b
.type b, @function
the type of 'a' is still object.
Since we do the computation in the end, we produce a function in both cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204555 91177308-0d34-0410-b5e6-96231b3b80d8
When a label is parsed, check if there is type information available for the
label. If so, check if the symbol is a function. If the symbol is a function
and we are in thumb mode and no explicit thumb_func has been emitted, adjust the
symbol data to indicate that the function definition is a thumb function.
The application of this inferencing is improved value handling in the object
file (the required thumb bit is set on symbols which are thumb functions). It
also helps improve compatibility with binutils.
The one complication that arises from this handling is the MCAsmStreamer. The
default implementation of getOrCreateSymbolData in MCStreamer does not support
tracking the symbol data. In order to support the semantics of thumb functions,
track symbol data in assembly streamer. Although O(n) in number of labels in
the TU, this is already done in various other streamers and as such the memory
overhead is not a practical concern in this scenario.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204544 91177308-0d34-0410-b5e6-96231b3b80d8
sym_a:
sym_d = sym_a + 1
This is the smallest fix I was able to extract from what got reverted in
r204203.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204527 91177308-0d34-0410-b5e6-96231b3b80d8
Add an assertion that the section is not NULL. Potential NULL pointer
dereference identified by clang static analyzer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204429 91177308-0d34-0410-b5e6-96231b3b80d8
The function exists to force an expression to be absolute, but there it is not
possible to force a symbol reference since
a = b
.long a
means something else.
This is an alternative fix for pr9951 that uses an assert. It then deletes
the old pr9951 test that was testing nothing already.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204399 91177308-0d34-0410-b5e6-96231b3b80d8
Given
bar = foo + 4
.long bar
MC would eat the 4. GNU as includes it in the relocation. The rule seems to be
that a variable that defines a symbol is used in the relocation and one that
does not define a symbol is evaluated and the result included in the relocation.
Fixing this unfortunately required some other changes:
* Since the variable is now evaluated, it would prevent the ELF writer from
noticing the weakref marker the elf streamer uses. This patch then replaces
that with a VariantKind in MCSymbolRefExpr.
* Using VariantKind then requires us to look past other VariantKind to see
.weakref bar,foo
call bar@PLT
doing this also fixes
zed = foo +2
call zed@PLT
so that is a good thing.
* Looking past VariantKind means that the relocation selection has to use
the fixup instead of the target.
This is a reboot of the previous fixes for MC. I will watch the sanitizer
buildbot and wait for a build before adding back the previous fixes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204294 91177308-0d34-0410-b5e6-96231b3b80d8
