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annotation will be superseded by more related functionality.
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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).
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When targeting the Darwin assembler, we need to generate markers ha16() and
lo16() to designate the high and low parts of a (symbolic) immediate. This
is necessary not just for plain symbols, but also for certain symbolic
expression, typically along the lines of ha16(A - B). The latter doesn't
work when simply using VariantKind flags on the symbol reference.
This is why the current back-end uses hacks (explicitly called out as such
via multiple FIXMEs) in the symbolLo/symbolHi print methods.
This patch uses target-defined MCExpr codes to represent the Darwin
ha16/lo16 constructs, following along the lines of the equivalent solution
used by the ARM back end to handle their :upper16: / :lower16: markers.
This allows us to get rid of special handling both in the symbolLo/symbolHi
print method and in the common code MCExpr::print routine. Instead, the
ha16 / lo16 markers are printed simply in a custom print routine for the
target MCExpr types. (As a result, the symbolLo/symbolHi print methods
can now replaced by a single printS16ImmOperand routine that also handles
symbolic operands.)
The patch also provides a EvaluateAsRelocatableImpl routine to handle
ha16/lo16 constructs. This is not actually used at the moment by any
in-tree code, but is provided as it makes merging into David Fang's
out-of-tree Mach-O object writer simpler.
Since there is no longer any need to treat VK_PPC_GAS_HA16 and
VK_PPC_DARWIN_HA16 differently, they are merged into a single
VK_PPC_ADDR16_HA (and likewise for the _LO16 types).
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API with my 176880 revision. If a bad Triple is passed in it can also assert.
In this case too it should just return 0 to indicate failure to create the
disassembler.
rdar://13955214
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We want the order to be deterministic on all platforms. NAKAMURA Takumi
fixed that in r181864. This patch is just two small cleanups:
* Move the function to the cpp file. It is only passed to array_pod_sort.
* Remove the ppc implementation which is now redundant
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Now that PowerPC no longer uses adjustFixupOffset, and no other
back-end (ever?) did, we can remove the infrastructure itself
(incidentally addressing a FIXME to that effect).
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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.
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As pointed out by Rafael Espindola, we should match the DWARF encodings
produced by GCC in both pic and non-pic modes. This was not the case
for the non-pic case.
This patch changes all DWARF encodings to DW_EH_PE_absptr for the
non-pic case, just like GCC does. The test case is updated to check
for both variants.
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This is another patch in preparation for adding the SystemZ target.
It defines the appropriate values for DWARF encodings; the intent
is to be compatible with what GCC currently does on the target.
Patch by Richard Sandiford.
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This patch adds support for PowerPC platform-specific variant
kinds in MCSymbolRefExpr::getVariantKindForName, and also
adds a test case to verify they are translated to the appropriate
fixup type.
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I know what would be cool! We should align the compact unwind section because
aligned data access is faster.
<rdar://problem/13723271>
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specific logic. This makes the code much less fragile. Test case coming on the
clang side in a moment.
rdar://13634327
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Add support for the COFF relocation types IMAGE_REL_I386_DIR32NB and
IMAGE_REL_AMD64_ADDR32NB for 32- and 64-bit respectively. These are
similar to normal 4-byte relocations except that they do not include
the base address of the image.
Image-relative relocations are used for debug information (32-bit) and
SEH unwind tables (64-bit).
A new MCSymbolRef variant called 'VK_COFF_IMGREL32' is introduced to
specify such relocations. For AT&T assembly, this variant can be accessed
using the symbol suffix '@imgrel'.
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Compact unwind has an encoding for when we're not able to generate compact
unwind and must generate an EH frame instead. Track that, but still emit that CU
encoding.
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Test cases that regressed due to r179115, plus a few more, were added in
r179182. Original commit message below:
[ms-inline asm] Use parsePrimaryExpr in lieu of parseExpression if we need to
parse an identifier. Otherwise, parseExpression may parse multiple tokens,
which makes it impossible to properly compute an immediate displacement.
An example of such a case is the source operand (i.e., [Symbol + ImmDisp]) in
the below example:
__asm mov eax, [Symbol + ImmDisp]
Part of rdar://13611297
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parse an identifier. Otherwise, parseExpression may parse multiple tokens,
which makes it impossible to properly compute an immediate displacement.
An example of such a case is the source operand (i.e., [Symbol + ImmDisp]) in
the below example:
__asm mov eax, [Symbol + ImmDisp]
The existing test cases exercise this patch.
rdar://13611297
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rather than deriving the StringRef from the Start and End SMLocs.
Using the Start and End SMLocs works fine for operands such as [Symbol], but
not for operands such as [Symbol + ImmDisp]. All existing test cases that
reference a variable exercise this patch.
rdar://13602265
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This finally fixes the encoding. The patch also
* Removes eh-frame.ll. It was an unnecessary .ll to .o test that was checking
the wrong value.
* Merge fde-reloc.s and eh-frame.s into a single test, since the only difference
was the run lines.
* Don't blindly test the content of the entire .eh_frame section. It makes it
hard to anyone actually fixing a bug and hitting a difference in a binary
blob. Instead, use a CHECK for each field and document what is being checked.
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Revision 177141 caused a regression in all but
mips64 little endian. That is because none of the
other Mips targets had test cases checking the
contents of the .eh_frame section. This patch fixes
both the llvm code and adds an assembler test case
to include the current 4 flavors.
The test cases unfortunately rely on llvm-objdump. A
preferable method would be to use a pretty printer output
such as what readelf -wf <elf_file> would give.
I also changed the name of the test case to correct a typo.
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'@SECREL' is what is used by the Microsoft assembler, but GNU as expects '@SECREL32'.
With the patch, the MC-generated code works fine in combination with a recent GNU as (2.23.51.20120920 here).
Patch by David Nadlinger!
Differential Revision: http://llvm-reviews.chandlerc.com/D429
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added back in by X86AsmPrinter::printIntelMemReference() during codegen.
Previously, this following example
void t() {
int i;
__asm mov eax, [i]
}
would generate the below assembly
mov eax, dword ptr [[eax]]
which resulted in a fatal error when compiling. Test case coming on the
clang side.
rdar://13444264
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This is a very late complement to r130637 which fixed this on x86_64. Fixes
pr15448.
Since it looks like that every elf architecture uses this encoding when using
cfi, make it the default for elf. Just exclude mips64el. It has a lovely
.ll -> .o test (ef_frame.ll) that tests that nothing changes in the binary
content of the .eh_frame produced by llc. Oblige it.
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return 0 to indicate failure to create the disassembler. A library routine
should not assert and just let the caller handler the error. For example
darwin's otool(1) will simply print an error if it ends up using a library
that is not configured for a target it wants:
% otool -tv ViewController.o
ViewController.o:
(__TEXT,__text) section
can't create arm llvm disassembler
This is much better than an abort which appears as a crash to the user or
even the assert when using a Debug+Asserts built library:
Assertion failed: (MAI && "Unable to create target asm info!"), function LLVMCreateDisasmCPU, file /Volumes/SandBox/llvm/lib/MC/MCDisassembler/Disassembler.cpp, line 47.
radr://12539918
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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
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For integer constants, allow 'L', 'UL' as well as 'ULL' and 'LL'. This provides
better support for shared headers between .s and .c files that define bunches
of constant values.
rdar://9321056
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The PowerPC TLS relocation types were not previously added to the
necessary list in MCELFStreamer::fixSymbolsInTLSFixups(). Now they are!
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excluding visibility bits.
Generic STO handling at the Target level.
The st_other field of the ELF symbol table is one
byte in size. The first 2 bytes are used for generic
visibility and are currently handled by llvm.
The other six bits are processor specific and need
to be set at the target level.
A couple of notes:
The new static methods for accessing and setting the "other"
flags in include/llvm/MC/MCELF.h match the style guide
and not the other methods in the file. I don't like the
inconsistency, but feel I should follow the prescribed
lowerUpper() convention.
STO_ value definitions are not specified in gnu land as
consistently as the STT_ and STB_ fields. Probably because
the latter were defined in a standards doc and the former
defined partially in code. I have stuck with the full byte
definition of the flags.
Contributer: Zoran Jovanovic
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GNU as rejects them and there are configure scripts in the wild that check if
the assembler rejects ".align 3" to determine whether the alignment is in bytes
or powers of two.
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Input/Output rewrite to the same location. Make sure the SizeDirective rewrite
is performed first. This also ensure the sort algorithm is stable.
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With bundle alignment, instructions all get their own MCFragments
(unless they are in a bundle-locked group). For instructions with
fixups, this is an MCDataFragment. Emitting actual data (e.g. for
.long) attempts to re-use MCDataFragments, which we don't want int
this case since it leads to fragments which exceed the bundle size.
So, don't reuse them in this case.
Also adds a test and fixes some formatting.
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Also, allow _EMIT and __EMIT for the emit directive. We already do the same
for TYPE, SIZE, and LENGTH.
rdar://13200215
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This is complicated by backward labels (e.g., 0b can be both a backward label
and a binary zero). The current implementation assumes [0-9]b is always a
label and thus it's possible for 0b and 1b to not be interpreted correctly for
ms-style inline assembly. However, this is relatively simple to fix in the
inline assembly (i.e., drop the [bB]).
This patch also limits backward labels to [0-9]b, so that only 0b and 1b are
ambiguous.
Part of rdar://12470373
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I have some uncommitted changes to the cast code that catch this sort of thing
at compile-time but I still need to do some other cleanup before I can enable
it.
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We generate one line table for each compilation unit in the object file.
Reviewed by Eric and Kevin.
rdar://problem/13067005
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Currently, when a fragment is relaxed, its size is modified, but its
offset is not (it gets laid out as a side effect of checking whether
it needs relaxation), then all subsequent fragments are invalidated
because their offsets need to change. When bundling is enabled,
relaxed fragments need to get laid out again, because the increase in
size may push it over a bundle boundary. So instead of only
invalidating subsequent fragments, also invalidate the fragment that
gets relaxed, which causes it to get laid out again.
This patch also fixes some trailing whitespace and fixes the
bundling-related debug output of MCFragments.
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The sh_link in the ELF section header of .ARM.exidx should
be filled with the section index of the corresponding text
section.
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isa<> and dyn_cast<>. In several places, code is already hacking around
the absence of this, and there seem to be several interfaces that might
be lifted and/or devirtualized using this.
This change was based on a discussion with Jim Grosbach about how best
to handle testing for specific MCStreamer subclasses. He said that this
was the correct end state, and everything else was too hacky so
I decided to just make it so.
No functionality should be changed here, this is just threading the kind
through all the constructors and setting up the classof overloads.
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This patch adds support for AArch64 (ARM's 64-bit architecture) to
LLVM in the "experimental" category. Currently, it won't be built
unless requested explicitly.
This initial commit should have support for:
+ Assembly of all scalar (i.e. non-NEON, non-Crypto) instructions
(except the late addition CRC instructions).
+ CodeGen features required for C++03 and C99.
+ Compilation for the "small" memory model: code+static data <
4GB.
+ Absolute and position-independent code.
+ GNU-style (i.e. "__thread") TLS.
+ Debugging information.
The principal omission, currently, is performance tuning.
This patch excludes the NEON support also reviewed due to an outbreak of
batshit insanity in our legal department. That will be committed soon bringing
the changes to precisely what has been approved.
Further reviews would be gratefully received.
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and update ELF header e_flags.
Currently gathering information such as symbol,
section and data is done by collecting it in an
MCAssembler object. From MCAssembler and MCAsmLayout
objects ELFObjectWriter::WriteObject() forms and
streams out the ELF object file.
This patch just adds a few members to the MCAssember
class to store and access the e_flag settings. It
allows for runtime additions to the e_flag by
assembler directives. The standalone assembler can
get to MCAssembler from getParser().getStreamer().getAssembler().
This patch is the generic infrastructure and will be
followed by patches for ARM and Mips for their target
specific use.
Contributer: Jack Carter
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the body does not use them and it appears the body has positional parameters.
This can cause unexpected results as in the added test case. As the darwin
version of gas(1) which only supported positional parameters, happened to
ignore the named parameters. Now that we want to support both styles of
macros we issue a warning in this specific case.
rdar://12861644
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an expression. Currently this bug causes the line to be ignored in a
release build and an assert in a debug build.
rdar://13062484
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Add the x32 environment kind to the triple, and separate the concept of
pointer size and callee save stack slot size, since they're not equal
on x32.
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but I cannot reproduce the problem and have scrubed my sources and
even tested with llvm-lit -v --vg.
Support for Mips register information sections.
Mips ELF object files have a section that is dedicated
to register use info. Some of this information such as
the assumed Global Pointer value is used by the linker
in relocation resolution.
The register info file is .reginfo in o32 and .MIPS.options
in 64 and n32 abi files.
This patch contains the changes needed to create the sections,
but leaves the actual register accounting for a future patch.
Contributer: Jack Carter
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