Revamp the SourceManager to separate the representation of parsed
source locations from source locations loaded from an AST/PCH file.
Previously, loading an AST/PCH file involved carefully pre-allocating
space at the beginning of the source manager for the source locations
and FileIDs that correspond to the prefix, and then appending the
source locations/FileIDs used for parsing the remaining translation
unit. This design forced us into loading PCH files early, as a prefix,
whic has become a rather significant limitation.
This patch splits the SourceManager space into two parts: for source
location "addresses", the lower values (growing upward) are used to
describe parsed code, while upper values (growing downward) are used
for source locations loaded from AST/PCH files. Similarly, positive
FileIDs are used to describe parsed code while negative FileIDs are
used to file/macro locations loaded from AST/PCH files. As a result,
we can load PCH/AST files even during parsing, making various
improvemnts in the future possible, e.g., teaching #include <foo.h> to
look for and load <foo.h.gch> if it happens to be already available.
This patch was originally written by Sebastian Redl, then brought
forward to the modern age by Jonathan Turner, and finally
polished/finished by me to be committed.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135484 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Basic/SourceLocation.h b/include/clang/Basic/SourceLocation.h
index ee5f96f..1cbcd40 100644
--- a/include/clang/Basic/SourceLocation.h
+++ b/include/clang/Basic/SourceLocation.h
@@ -35,8 +35,9 @@
/// a source file (MemoryBuffer) along with its #include path and #line data.
///
class FileID {
- /// ID - Opaque identifier, 0 is "invalid".
- unsigned ID;
+ /// ID - Opaque identifier, 0 is "invalid". >0 is this module, <-1 is
+ /// something loaded from another module.
+ int ID;
public:
FileID() : ID(0) {}
@@ -49,26 +50,38 @@
bool operator>(const FileID &RHS) const { return RHS < *this; }
bool operator>=(const FileID &RHS) const { return RHS <= *this; }
- static FileID getSentinel() { return get(~0U); }
- unsigned getHashValue() const { return ID; }
+ static FileID getSentinel() { return get(-1); }
+ unsigned getHashValue() const { return static_cast<unsigned>(ID); }
private:
friend class SourceManager;
friend class ASTWriter;
friend class ASTReader;
- static FileID get(unsigned V) {
+ static FileID get(int V) {
FileID F;
F.ID = V;
return F;
}
- unsigned getOpaqueValue() const { return ID; }
+ int getOpaqueValue() const { return ID; }
};
-/// SourceLocation - This is a carefully crafted 32-bit identifier that encodes
-/// a full include stack, line and column number information for a position in
-/// an input translation unit.
+/// \brief Encodes a location in the source. The SourceManager can decode this
+/// to get at the full include stack, line and column information.
+///
+/// Technically, a source location is simply an offset into the manager's view
+/// of the input source, which is all input buffers (including macro
+/// instantiations) concatenated in an effectively arbitrary order. The manager
+/// actually maintains two blocks of input buffers. One, starting at offset 0
+/// and growing upwards, contains all buffers from this module. The other,
+/// starting at the highest possible offset and growing downwards, contains
+/// buffers of loaded modules.
+///
+/// In addition, one bit of SourceLocation is used for quick access to the
+/// information whether the location is in a file or a macro instantiation.
+///
+/// It is important that this type remains small. It is currently 32 bits wide.
class SourceLocation {
unsigned ID;
friend class SourceManager;
@@ -77,21 +90,21 @@
};
public:
- SourceLocation() : ID(0) {} // 0 is an invalid FileID.
+ SourceLocation() : ID(0) {}
bool isFileID() const { return (ID & MacroIDBit) == 0; }
bool isMacroID() const { return (ID & MacroIDBit) != 0; }
- /// isValid - Return true if this is a valid SourceLocation object. Invalid
- /// SourceLocations are often used when events have no corresponding location
- /// in the source (e.g. a diagnostic is required for a command line option).
+ /// \brief Return true if this is a valid SourceLocation object.
///
+ /// Invalid SourceLocations are often used when events have no corresponding
+ /// location in the source (e.g. a diagnostic is required for a command line
+ /// option).
bool isValid() const { return ID != 0; }
bool isInvalid() const { return ID == 0; }
private:
- /// getOffset - Return the index for SourceManager's SLocEntryTable table,
- /// note that this is not an index *into* it though.
+ /// \brief Return the offset into the manager's global input view.
unsigned getOffset() const {
return ID & ~MacroIDBit;
}
@@ -114,7 +127,8 @@
/// getFileLocWithOffset - Return a source location with the specified offset
/// from this file SourceLocation.
SourceLocation getFileLocWithOffset(int Offset) const {
- assert(((getOffset()+Offset) & MacroIDBit) == 0 && "invalid location");
+ assert(((getOffset()+Offset) & MacroIDBit) == 0 &&
+ "offset overflow or macro loc");
SourceLocation L;
L.ID = ID+Offset;
return L;