9eeafc63d2
This PR implements a CC1 flag `-dump-minimization-hints`.
The flag allows to specify a file path to dump ranges of deserialized
declarations in `ASTReader`. Example usage:
```
clang -Xclang=-dump-minimization-hints=/tmp/decls -c file.cc -o file.o
```
Example output:
```
// /tmp/decls
{
"required_ranges": [
{
"file": "foo.h",
"range": [
{
"from": {
"line": 26,
"column": 1
},
"to": {
"line": 27,
"column": 77
}
}
]
},
{
"file": "bar.h",
"range": [
{
"from": {
"line": 30,
"column": 1
},
"to": {
"line": 35,
"column": 1
}
},
{
"from": {
"line": 92,
"column": 1
},
"to": {
"line": 95,
"column": 1
}
}
]
}
]
}
```
Specifying the flag creates an instance of
`DeserializedDeclsSourceRangePrinter`, which dumps ranges of deserialized
declarations to aid debugging and bug minimization (we use is as input to [C-Vise](https://github.com/emaxx-google/cvise/tree/multifile-hints).
Required ranges are computed from source ranges of Decls.
`TranslationUnitDecl`, `LinkageSpecDecl` and `NamespaceDecl` are ignored
for the sake of this PR.
Technical details:
* `DeserializedDeclsSourceRangePrinter` implements `ASTConsumer` and
`ASTDeserializationListener`, so that an object of
`DeserializedDeclsSourceRangePrinter` registers as its own listener.
* `ASTDeserializationListener` interface provides the `DeclRead`
callback that we use to collect the deserialized Decls.
Printing or otherwise processing them as this point is dangerous, since
that could trigger additional deserialization and crash compilation.
* The collected Decls are processed in `HandleTranslationUnit` method of
`ASTConsumer`. This is a safe point, since we know that by this point
all the Decls needed by the compiler frontend have been deserialized.
* In case our processing causes further deserialization, `DeclRead` from
the listener might be called again. However, at that point we don't
accept any more Decls for processing.
C language Family Front-end
Welcome to Clang.
This is a compiler front-end for the C family of languages (C, C++ and Objective-C) which is built as part of the LLVM compiler infrastructure project.
Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source-level tools. One example of this is the Clang Static Analyzer.
If you're interested in more (including how to build Clang) it is best to read the relevant websites. Here are some pointers:
-
Information on Clang: http://clang.llvm.org/
-
Building and using Clang: http://clang.llvm.org/get_started.html
-
Clang Static Analyzer: http://clang-analyzer.llvm.org/
-
Information on the LLVM project: http://llvm.org/
-
If you have questions or comments about Clang, a great place to discuss them is on the Clang forums:
-
If you find a bug in Clang, please file it in the LLVM bug tracker: