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[ClangImporter] Deduplicate clang buffers representing the same file #84904

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Merged
merged 3 commits into from
Oct 18, 2025
Merged

[ClangImporter] Deduplicate clang buffers representing the same file #84904

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696c08e
[ClangImporter] Deduplicate clang buffers representing the same file
hnrklssn Oct 15, 2025
d69c021
[ClangImporter] check if buffer represents file before dedup
hnrklssn Oct 17, 2025
acc967b
Remove assert that path exists on file system
hnrklssn Oct 17, 2025
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18 changes: 13 additions & 5 deletions lib/ClangImporter/ClangSourceBufferImporter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
//===----------------------------------------------------------------------===//

#include "ClangSourceBufferImporter.h"
#include "swift/Basic/Assertions.h"
#include "swift/Basic/SourceManager.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/Support/MemoryBuffer.h"
Expand Down Expand Up @@ -47,12 +48,19 @@ SourceLoc ClangSourceBufferImporter::resolveSourceLocation(
if (mirrorIter != mirroredBuffers.end()) {
mirrorID = mirrorIter->second;
} else {
StringRef bufIdent = buffer.getBufferIdentifier();
std::unique_ptr<llvm::MemoryBuffer> mirrorBuffer{
llvm::MemoryBuffer::getMemBuffer(buffer.getBuffer(),
buffer.getBufferIdentifier(),
/*RequiresNullTerminator=*/true)
};
mirrorID = swiftSourceManager.addNewSourceBuffer(std::move(mirrorBuffer));
llvm::MemoryBuffer::getMemBuffer(buffer.getBuffer(), bufIdent,
/*RequiresNullTerminator=*/true)};
// The same underlying file can exist as multiple clang file IDs. E.g. as
// part of the its own module, and then later loaded as an import in another
// module. Don't deduplicate files like "<module-imports>" that have
// different contents in different modules, despite the same name.
auto IDOpt = swiftSourceManager.getIDForBufferIdentifier(bufIdent);
if (IDOpt.has_value() && clangSrcMgr.getFileEntryForID(clangFileID)) {
mirrorID = IDOpt.value();
} else
mirrorID = swiftSourceManager.addNewSourceBuffer(std::move(mirrorBuffer));
mirroredBuffers[buffer.getBufferStart()] = mirrorID;
}
loc = swiftSourceManager.getLocForOffset(mirrorID, decomposedLoc.second);
Expand Down