This patch adds support for creating modules from JSON object files.
This is necessary for the crashlog use case where we don't have either a
module or a symbol file. In that case the ObjectFileJSON serves as both.
The patch adds support for an object file type (i.e. executable, shared
library, etc). It also adds the ability to specify sections, which is
necessary in order specify symbols by address. Finally, this patch
improves error handling and fixes a bug where we wouldn't read more than
the initial 512 bytes in GetModuleSpecifications.
Differential revision: https://reviews.llvm.org/D148062
Introduce a new object and symbol file format with the goal of mapping
addresses to symbol names. I'd like to think of is as an extremely
simple textual symtab. The file format consists of a triple, a UUID and
a list of symbols. JSON is used for the encoding, but that's mostly an
implementation detail. The goal of the format was to be simple and human
readable.
The new file format is motivated by two use cases:
- Stripped binaries: when a binary is stripped, you lose the ability to
do thing like setting symbolic breakpoints. You can keep the
unstripped binary around, but if all you need is the stripped
symbols then that's a lot of overhead. Instead, we could save the
stripped symbols to a file and load them in the debugger when
needed. I want to extend llvm-strip to have a mode where it emits
this new file format.
- Interactive crashlogs: with interactive crashlogs, if we don't have
the binary or the dSYM for a particular module, we currently show an
unnamed symbol for those frames. This is a regression compared to the
textual format, that has these frames pre-symbolicated. Given that
this information is available in the JSON crashlog, we need a way to
tell LLDB about it. With the new symbol file format, we can easily
synthesize a symbol file for each of those modules and load them to
symbolicate those frames.
Here's an example of the file format:
{
"triple": "arm64-apple-macosx13.0.0",
"uuid": "36D0CCE7-8ED2-3CA3-96B0-48C1764DA908",
"symbols": [
{
"name": "main",
"type": "code",
"size": 32,
"address": 4294983568
},
{
"name": "foo",
"type": "code",
"size": 8,
"address": 4294983560
}
]
}
Differential revision: https://reviews.llvm.org/D145180
