On AArch64, we create optional/weak relocations that may not be
processed due to the relocated value overflow. When the overflow
happens, we used to enforce patching for all functions in the binary via
--force-patch option. This PR relaxes the requirement, and enforces
patching only for functions that are target of optional relocations.
Moreover, if the compact code model is used, the relocation overflow is
guaranteed not to happen and the patching will be skipped.
With --force-patch option, every original function entry point is
overwritten with a trampoline to a new version of the function to
prevent the execution of the original code.
If the function size is too small for the trampoline code, we are forced
to bail out on rewriting the function. That presented a problem on
AArch64 due to LongJmp pass that assumed the presence of the new copy of
the function. If the new copy was not emitted it could have lead to a
relocation overflow.
Run PatchEntries pass before LongJmp and make the latter aware of the
functions that are not going to be emitted. Make --force-patch option
behavior on AArch64 consistent with other architectures.
Add BinaryContext::createInstructionPatch() interface for patching parts
of the original binary with new instruction sequences. Refactor
PatchEntries pass to use the new interface.
Make core BOLT functionality more friendly to being used as a
library instead of in our standalone driver llvm-bolt. To
accomplish this, we augment BinaryContext with journaling streams
that are to be used by most BOLT code whenever something needs to
be logged to the screen. Users of the library can decide if logs
should be printed to a file, no file or to the screen, as
before. To illustrate this, this patch adds a new option
`--log-file` that allows the user to redirect BOLT logging to a
file on disk or completely hide it by using
`--log-file=/dev/null`. Future BOLT code should now use
`BinaryContext::outs()` for printing important messages instead of
`llvm::outs()`. A new test log.test enforces this by verifying that
no strings are print to screen once the `--log-file` option is
used.
In previous patches we also added a new BOLTError class to report
common and fatal errors, so code shouldn't call exit(1) now. To
easily handle problems as before (by quitting with exit(1)),
callers can now use
`BinaryContext::logBOLTErrorsAndQuitOnFatal(Error)` whenever code
needs to deal with BOLT errors. To test this, we have fatal.s
that checks we are correctly quitting and printing a fatal error
to the screen.
Because this is a significant change by itself, not all code was
yet ported. Code from Profiler libs (DataAggregator and friends)
still print errors directly to screen.
Co-authored-by: Rafael Auler <rafaelauler@fb.com>
Test Plan: NFC
As part of the effort to refactor old error handling code that
would directly call exit(1), in this patch we add a new class
BOLTError and auxiliary functions `createFatalBOLTError()` and
`createNonFatalBOLTError()` that allow BOLT code to bubble up the
problem to the caller by using the Error class as a return
type (or Expected). Also changes passes to use these.
Co-authored-by: Rafael Auler <rafaelauler@fb.com>
Test Plan: NFC
As part of the effort to refactor old error handling code that
would directly call exit(1), in this patch we change the
interface to `BinaryFunctionPass` to return an Error on
`runOnFunctions()`. This gives passes the ability to report a
serious problem to the caller (RewriteInstance class), so the
caller may decide how to best handle the exceptional situation.
Co-authored-by: Rafael Auler <rafaelauler@fb.com>
Test Plan: NFC
Due to LongJmp pass that is executed before PatchEntries we can't ignore
the function here since it would change pre-calculated output layout.
The test reloc-26 relied on the wrong behavior, rewritten to unittest.
This is also attemp to fix#70771
Summary:
Refactor members of BinaryBasicBlock. Replace some std containers with
ADT equivalents. The size of BinaryBasicBlock on x86-64 Linux is reduced
from 232 bytes to 192 bytes.
(cherry picked from FBD33081850)
Summary:
Moves source files into separate components, and make explicit
component dependency on each other, so LLVM build system knows how to
build BOLT in BUILD_SHARED_LIBS=ON.
Please use the -c merge.renamelimit=230 git option when rebasing your
work on top of this change.
To achieve this, we create a new library to hold core IR files (most
classes beginning with Binary in their names), a new library to hold
Utils, some command line options shared across both RewriteInstance
and core IR files, a new library called Rewrite to hold most classes
concerned with running top-level functions coordinating the binary
rewriting process, and a new library called Profile to hold classes
dealing with profile reading and writing.
To remove the dependency from BinaryContext into X86-specific classes,
we do some refactoring on the BinaryContext constructor to receive a
reference to the specific backend directly from RewriteInstance. Then,
the dependency on X86 or AArch64-specific classes is transfered to the
Rewrite library. We can't have the Core library depend on targets
because targets depend on Core (which would create a cycle).
Files implementing the entry point of a tool are transferred to the
tools/ folder. All header files are transferred to the include/
folder. The src/ folder was renamed to lib/.
(cherry picked from FBD32746834)
