Add support for having multiple sections with the same name and comdat.
Using this in combination with -ffunction-sections allows LLVM to output a .o
file with mulitple sections named .text. This saves space by avoiding long
unique names of the form .text.<C++ mangled name>.
llvm-svn: 229541
regressions for LLDB on Linux. Rafael indicated on lldb-dev that we
should just go ahead and revert these but that he wasn't at a computer.
The patches backed out are as follows:
r228980: Add support for having multiple sections with the name and ...
r228889: Invert the section relocation map.
r228888: Use the existing SymbolTableIndex intsead of doing a lookup.
r228886: Create the Section -> Rel Section map when it is first needed.
These patches look pretty nice to me, so hoping its not too hard to get
them re-instated. =D
llvm-svn: 229080
Using this in combination with -ffunction-sections allows LLVM to output a .o
file with mulitple sections named .text. This saves space by avoiding long
unique names of the form .text.<C++ mangled name>.
llvm-svn: 228980
Any code creating an MCSectionELF knows ELF and already provides the flags.
SectionKind is an abstraction used by common code that uses a plain
MCSection.
Use the flags to compute the SectionKind. This removes a lot of
guessing and boilerplate from the MCSectionELF construction.
llvm-svn: 227476
These intrinsics allow multiple functions to share a single stack
allocation from one function's call frame. The function with the
allocation may only perform one allocation, and it must be in the entry
block.
Functions accessing the allocation call llvm.recoverframeallocation with
the function whose frame they are accessing and a frame pointer from an
active call frame of that function.
These intrinsics are very difficult to inline correctly, so the
intention is that they be introduced rarely, or at least very late
during EH preparation.
Reviewers: echristo, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D6493
llvm-svn: 225746
The only difference from r219829 is using
getOrCreateSectionSymbol(*ELFSec)
instead of
GetOrCreateSymbol(ELFSec->getSectionName())
in ELFObjectWriter which causes us to use the correct section symbol even if
we have multiple sections with the same name.
Original messages:
r219829:
Correctly handle references to section symbols.
When processing assembly like
.long .text
we were creating a new undefined symbol .text. GAS on the other hand would
handle that as a reference to the .text section.
This patch implements that by creating the section symbols earlier so that
they are visible during asm parsing.
The patch also updates llvm-readobj to print the symbol number in the relocation
dump so that the test can differentiate between two sections with the same name.
r219835:
Allow forward references to section symbols.
llvm-svn: 220021
Revert "Correctly handle references to section symbols."
Revert "Allow forward references to section symbols."
Rui found a regression I am debugging.
llvm-svn: 220010
When processing assembly like
.long .text
we were creating a new undefined symbol .text. GAS on the other hand would
handle that as a reference to the .text section.
This patch implements that by creating the section symbols earlier so that
they are visible during asm parsing.
The patch also updates llvm-readobj to print the symbol number in the relocation
dump so that the test can differentiate between two sections with the same name.
llvm-svn: 219829
Summary:
This fixes a long standing issue where we would emit many little .text
sections and only one .pdata and .xdata section. Now we generate one
.pdata / .xdata pair per .text section and associate them correctly.
Fixes PR19667.
Reviewers: majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5181
llvm-svn: 217176
COFF sections in MC were represented by a tuple of section-name and
COMDAT-name. This is not sufficient to represent a .text section
associated with another .text section; we need a way to distinguish
between the key section and the one marked associative.
llvm-svn: 211913
Currently, when using llvm as an assembler, DWARF debug information is only
generated for the .text section. This patch modifies this so that DWARF info
is emitted for all executable sections.
llvm-svn: 211273
* Section association cannot use just the section name as many
sections can have the same name. With this patch, the comdat symbol in
an assoc section is interpreted to mean a symbol in the associated
section and the mapping is discovered from it.
* Comdat symbols were not being set correctly. Instead we were getting
whatever was output first for that section.
A consequence is that associative sections now must use .section to
set the association. Using .linkonce would not work since it is not
possible to change a sections comdat symbol (it is used to decide if
we should create a new section or reuse an existing one).
This includes r210298, which was reverted because it was asserting
on an associated section having the same comdat as the associated
section.
llvm-svn: 210367
from places like MCCodeEmitter() in the MC backend when the
MCContext is const.
I was going to use this in my change for r206669 but Jim convinced
me to use an assert there. But this still is a good tweak.
llvm-svn: 206923
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).
llvm-svn: 206003
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.
llvm-svn: 205990
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.
llvm-svn: 205287
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.
llvm-svn: 205081
Our handling of compilation directory in DwarfDebug was broken
(incorrectly using the 'last' compilation directory (that of the last
CU in the metadata list) for all function emission in any CU). By moving
this handling down into MCDwarf the issue is fixed as the compilation
dir is tracked correctly per line table.
llvm-svn: 204089
The previous deduping strategy was woefully inadequate - it only
considered the most recent file used and avoided emitting a duplicate in
that case - never considering the a/b/a scenario.
It was also lacking when it came to directory paths as the previous
filename would never match the current if the filename had been split
into file and directory components.
This change builds caching functionality into the line table at the
lowest level in an optional form (a file number of 0 indicates that one
should be chosen and returned) and will eventually be reused by the
normal source level debugging DWARF emission.
llvm-svn: 204027
There aren't /that/ many files, and we are already using various maps
and other standard containers that don't use MCContext's allocator to
store these values, so this doesn't seem to be critical and simplifies
the design (I'll be moving construction out of MCContext shortly so it'd
be annoying to have to pass the allocator around to allocate these
things... and we'll have non-MCContext users (debug_line.dwo) shortly)
llvm-svn: 203831
This changes the implementation of local directional labels to use a dedicated
map. With that it can then just use CreateTempSymbol, which is what the rest
of MC uses.
CreateTempSymbol doesn't do a great job at making sure the names are unique
(or being efficient when the names are not needed), but that should probably
be fixed in a followup patch.
This fixes pr18928.
llvm-svn: 203826
This replaces several "compile unit ID -> thing" mappings in favor of
one mapping from CUID to the whole line table structure (files,
directories, and lines).
This is another step along the way to refactoring out reusable
components of line table handling for use when generating debug_line.dwo
for fission type units.
Also, might be a good basis to fold some of this handling down into
MCStreamers to avoid the special case of "One line table when doing asm
printing, line table per CU otherwise" by building it into the different
MCStreamer implementations.
llvm-svn: 203821
This makes the mapping consistent with other CU->X mappings in the
MCContext, helping pave the way to refactor all these values into a
single data structure per CU and thus a single map.
I haven't renamed the data structure as that would make the patch churn
even higher (the MCLineSection name no longer makes sense, as this
structure now contains lines for multiple sections covered by a single
CU, rather than lines for a single section in multiple CUs) and further
refactorings will follow that may remove this type entirely.
For convenience, I also gave the MCLineSection value semantics so we
didn't have to do the lazy construction, manual delete, etc.
(& for those playing at home, refactoring the line printing into a
single data structure will eventually alow that data structure to be
reused to own the debug_line.dwo line table used for type unit file name
resolution)
llvm-svn: 203726
MCJIT needs to be able to run in hostile environments, even when PWD
is invalid. There's no need to crash MCJIT in this case.
The obvious fix is to simply leave MCContext's CompilationDir empty
when PWD can't be determined. This way, MCJIT clients,
and other clients that link with LLVM don’t need a valid working directory.
If we do want to guarantee valid CompilationDir, that should be done
only for clients of getCompilationDir(). This is as simple as checking
for an empty string.
The only current use of getCompilationDir is EmitGenDwarfInfo, which
won’t conceivably run with an invalid working dir. However, in the
purely hypothetically and untestable case that this happens, the
AT_comp_dir will be omitted from the compilation_unit DIE.
llvm-svn: 196874
This is the first step to fix pr17918.
It extends the .section directive a bit, inspired by what the ELF one looks
like. The problem with using linkonce is that given
.section foo
.linkonce....
.section foo
.linkonce
we would already have switched sections when getting to .linkonce. The cleanest
solution seems to be to add the comdat information in the .section itself.
llvm-svn: 195148
We now emit a line table for each compile unit. To reduce the prologue size
of each line table, the files and directories used by each compile unit are
stored in std::map<unsigned, std::vector< > > instead of std::vector< >.
The prologue for a lto'ed image can be as big as 93K. Duplicating 93K for each
compile unit causes a huge increase of debug info. With this patch, each
prologue will only emit the files required by the compile unit.
rdar://problem/13342023
llvm-svn: 176605
AT_producer. Which includes clang's version information so we can tell
which version of the compiler was used.
This is the first of two steps to allow us to do that. This is the llvm-mc
change to provide a method to set the AT_producer string. The second step,
coming soon to a clang near you, will have the clang driver pass the value
of getClangFullVersion() via an flag when invoking the integrated assembler
on assembly source files.
rdar://12955296
llvm-svn: 172630
compilation directory.
This defaults to the current working directory, just as it always has,
but now an assembler can choose to override it with a custom directory.
I've taught llvm-mc about this option and added a test case.
llvm-svn: 170371
original change description:
change MCContext to work on the doInitialization/doFinalization model
reviewed by Evan Cheng <evan.cheng@apple.com>
llvm-svn: 169553
AKA: Recompile *ALL* the source code!
This one went much better. No manual edits here. I spot-checked for
silliness and grep-checked for really broken edits and everything seemed
good. It all still compiles. Yell if you see something that looks goofy.
llvm-svn: 169133
