Like yaml ObjectFiles, this will be very useful for testing the MC CFG
implementation (mostly MCObjectDisassembler), by matching the output
with YAML, and for potential users of the MC CFG, by using it as an input.
There isn't much to the actual format, it is just a serialization of the
MCModule class. Of note:
- Basic block references (pred/succ, ..) are represented by the BB's
start address.
- Just as in the MC CFG, instructions are MCInsts with a size.
- Operands have a prefix representing the type (only register and
immediate supported here).
- Instruction opcodes are represented by their names; enum values aren't
stable, enum names mostly are: usually, a change to a name would need
lots of changes in the backend anyway.
Same with registers.
All in all, an example is better than 1000 words, here goes:
A simple binary:
Disassembly of section __TEXT,__text:
_main:
100000f9c: 48 8b 46 08 movq 8(%rsi), %rax
100000fa0: 0f be 00 movsbl (%rax), %eax
100000fa3: 3b 04 25 48 00 00 00 cmpl 72, %eax
100000faa: 0f 8c 07 00 00 00 jl 7 <.Lend>
100000fb0: 2b 04 25 48 00 00 00 subl 72, %eax
.Lend:
100000fb7: c3 ret
And the (pretty verbose) generated YAML:
---
Atoms:
- StartAddress: 0x0000000100000F9C
Size: 20
Type: Text
Content:
- Inst: MOV64rm
Size: 4
Ops: [ RRAX, RRSI, I1, R, I8, R ]
- Inst: MOVSX32rm8
Size: 3
Ops: [ REAX, RRAX, I1, R, I0, R ]
- Inst: CMP32rm
Size: 7
Ops: [ REAX, R, I1, R, I72, R ]
- Inst: JL_4
Size: 6
Ops: [ I7 ]
- StartAddress: 0x0000000100000FB0
Size: 7
Type: Text
Content:
- Inst: SUB32rm
Size: 7
Ops: [ REAX, REAX, R, I1, R, I72, R ]
- StartAddress: 0x0000000100000FB7
Size: 1
Type: Text
Content:
- Inst: RET
Size: 1
Ops: [ ]
Functions:
- Name: __text
BasicBlocks:
- Address: 0x0000000100000F9C
Preds: [ ]
Succs: [ 0x0000000100000FB7, 0x0000000100000FB0 ]
<snip>
...
llvm-svn: 188890
* ELFTypes.h contains template magic for defining types based on endianess, size, and alignment.
* ELFFile.h defines the ELFFile class which provides low level ELF specific access.
* ELFObjectFile.h contains ELFObjectFile which uses ELFFile to implement the ObjectFile interface.
llvm-svn: 188022
These records are mandatory for executables and are used by the loader.
Reviewers: rafael
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D939
llvm-svn: 183852
from the LC_DATA_IN_CODE load command. And when disassembling print
the data in code formatted for the kind of data it and not disassemble those
bytes.
I added the format specific functionality to the derived class MachOObjectFile
since these tables only appears in Mach-O object files. This is my first
attempt to modify the libObject stuff so if folks have better suggestions
how to fit this in or suggestions on the implementation please let me know.
rdar://11791371
llvm-svn: 183424
In ELF (as in MachO), not all relocations point to symbols. Represent this
properly by using a symbol_iterator instead of a SymbolRef. Update llvm-readobj
ELF's dumper to handle relocatios without symbols.
llvm-svn: 183284
This patch builds on some existing code to do CFG reconstruction from
a disassembled binary:
- MCModule represents the binary, and has a list of MCAtoms.
- MCAtom represents either disassembled instructions (MCTextAtom), or
contiguous data (MCDataAtom), and covers a specific range of addresses.
- MCBasicBlock and MCFunction form the reconstructed CFG. An MCBB is
backed by an MCTextAtom, and has the usual successors/predecessors.
- MCObjectDisassembler creates a module from an ObjectFile using a
disassembler. It first builds an atom for each section. It can also
construct the CFG, and this splits the text atoms into basic blocks.
MCModule and MCAtom were only sketched out; MCFunction and MCBB were
implemented under the experimental "-cfg" llvm-objdump -macho option.
This cleans them up for further use; llvm-objdump -d -cfg now generates
graphviz files for each function found in the binary.
In the future, MCObjectDisassembler may be the right place to do
"intelligent" disassembly: for example, handling constant islands is just
a matter of splitting the atom, using information that may be available
in the ObjectFile. Also, better initial atom formation than just using
sections is possible using symbols (and things like Mach-O's
function_starts load command).
This brings two minor regressions in llvm-objdump -macho -cfg:
- The printing of a relocation's referenced symbol.
- An annotation on loop BBs, i.e., which are their own successor.
Relocation printing is replaced by the MCSymbolizer; the basic CFG
annotation will be superseded by more related functionality.
llvm-svn: 182628
This is a basic first step towards symbolization of disassembled
instructions. This used to be done using externally provided (C API)
callbacks. This patch introduces:
- the MCSymbolizer class, that mimics the same functions that were used
in the X86 and ARM disassemblers to symbolize immediate operands and
to annotate loads based off PC (for things like c string literals).
- the MCExternalSymbolizer class, which implements the old C API.
- the MCRelocationInfo class, which provides a way for targets to
translate relocations (either object::RelocationRef, or disassembler
C API VariantKinds) to MCExprs.
- the MCObjectSymbolizer class, which does symbolization using what it
finds in an object::ObjectFile. This makes simple symbolization (with
no fancy relocation stuff) work for all object formats!
- x86-64 Mach-O and ELF MCRelocationInfos.
- A basic ARM Mach-O MCRelocationInfo, that provides just enough to
support the C API VariantKinds.
Most of what works in otool (the only user of the old symbolization API
that I know of) for x86-64 symbolic disassembly (-tvV) works, namely:
- symbol references: call _foo; jmp 15 <_foo+50>
- relocations: call _foo-_bar; call _foo-4
- __cf?string: leaq 193(%rip), %rax ## literal pool for "hello"
Stub support is the main missing part (because libObject doesn't know,
among other things, about mach-o indirect symbols).
As for the MCSymbolizer API, instead of relying on the disassemblers
to call the tryAdding* methods, maybe this could be done automagically
using InstrInfo? For instance, even though PC-relative LEAs are used
to get the address of string literals in a typical Mach-O file, a MOV
would be used in an ELF file. And right now, the explicit symbolization
only recognizes PC-relative LEAs. InstrInfo should have already have
most of what is needed to know what to symbolize, so this can
definitely be improved.
I'd also like to remove object::RelocationRef::getValueString (it seems
only used by relocation printing in objdump), as simply printing the
created MCExpr is definitely enough (and cleaner than string concats).
llvm-svn: 182625
It was just a less powerful and more confusing version of
MCCFIInstruction. A side effect is that, since MCCFIInstruction uses
dwarf register numbers, calls to getDwarfRegNum are pushed out, which
should allow further simplifications.
I left the MachineModuleInfo::addFrameMove interface unchanged since
this patch was already fairly big.
llvm-svn: 181680
getRelocationAddress is for dynamic libraries and executables,
getRelocationOffset for relocatable objects.
Mark the getRelocationAddress of COFF and MachO as not implemented yet. Add a
test of ELF's. llvm-readobj -r now prints the same values as readelf -r.
llvm-svn: 180259
Thanks to Evgeniy Stepanov for reporting this.
It might be a good idea to add a command iterator abstraction to MachO.h, but
this fixes the bug for now.
llvm-svn: 179848
LoadCommandInfo was needed to keep a command and its offset in the file. Now
that we always have a pointer to the command, we don't need the offset.
llvm-svn: 178991
InMemoryStruct is extremely dangerous as it returns data from an internal
buffer when the endiannes doesn't match. This should fix the tests on big
endian hosts.
llvm-svn: 178875
This simplifies the usage and implementation of ELFObjectFile by using ELFType
to replace:
<endianness target_endianness, std::size_t max_alignment, bool is64Bits>
This does complicate the base ELF types as they must now use template template
parameters to partially specialize for the 32 and 64bit cases. However these
are only defined once.
llvm-svn: 172515
On MachO, sections also have segment names. When a tool looking at a .o file
prints a segment name, this is what they mean. In reality, a .o has only one
anonymous, segment.
This patch adds a MachO only function to fetch that segment name. I named it
getSectionFinalSegmentName since the main use for the name seems to be inform
the linker with segment this section should go to.
The patch also changes MachOObjectFile::getSectionName to return just the
section name instead of computing SegmentName,SectionName.
The main difference from the previous patch is that it doesn't use
InMemoryStruct. It is extremely dangerous: if the endians match it returns
a pointer to the file buffer, if not, it returns a pointer to an internal buffer
that is overwritten in the next API call.
We should change all of this code to use
support::detail::packed_endian_specific_integral like ELF, but since these
functions only handle strings, they work with big and little endian machines
as is.
I have tested this by installing ubuntu 12.10 ppc on qemu, that is why it took
so long :-)
llvm-svn: 170838
I cannot reproduce it the failures locally, so I will keep an eye at the ppc
bots. This patch does add the change to the "Disassembly of section" message,
but that is not what was failing on the bots.
Original message:
Add a funciton to get the segment name of a section.
On MachO, sections also have segment names. When a tool looking at a .o file
prints a segment name, this is what they mean. In reality, a .o has only one
anonymous, segment.
This patch adds a MachO only function to fetch that segment name. I named it
getSectionFinalSegmentName since the main use for the name seems to be infor
the linker with segment this section should go to.
The patch also changes MachOObjectFile::getSectionName to return just the
section name instead of computing SegmentName,SectionName.
llvm-svn: 170545
Charles Davis