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[clangd] Selection: Prune gtest TEST()s earlier 

When searching for AST nodes that may overlap the selection, mayHit() was only
attempting to prune nodes whose begin/end are both in the main file.

While failing to prune never gives wrong results, it hurts performance.
In GTest unit-tests, `TEST()` macros at the top level declare classes.
These were never pruned and we traversed *every* such class for any selection.

We fix this by reasoning about what tokens such a node might claim.
They must lie within its ultimate macro expansion range, so if this doesn't
overlap with the selection, we can prune the node.

Differential Revision: https://reviews.llvm.org/D116978
This commit is contained in:
Sam McCall 2022-01-11 00:09:58 +01:00
parent a9bf32763d
commit 2b2dbe6126
1 changed files with 20 additions and 5 deletions
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25
clang-tools-extra/clangd/Selection.cpp
View File

@ -8,7 +8,6 @@
#include "Selection.h"
#include "AST.h"
#include "SourceCode.h"
#include "support/Logger.h"
#include "support/Trace.h"
#include "clang/AST/ASTTypeTraits.h"
@ -303,10 +302,21 @@ public:
bool mayHit(SourceRange R) const {
if (SpelledTokens.empty())
return false;
auto B = offsetInSelFile(R.getBegin());
auto E = offsetInSelFile(R.getEnd());
if (B && E)
if (*E < SpelledTokens.front().Offset || *B > SpelledTokens.back().Offset)
// If the node starts after the selection ends, it is not selected.
// Tokens a macro location might claim are >= its expansion start.
// So if the expansion start > last selected token, we can prune it.
// (This is particularly helpful for GTest's TEST macro).
if (auto B = offsetInSelFile(getExpansionStart(R.getBegin())))
if (*B > SpelledTokens.back().Offset)
return false;
// If the node ends before the selection begins, it is not selected.
SourceLocation EndLoc = R.getEnd();
while (EndLoc.isMacroID())
EndLoc = SM.getImmediateExpansionRange(EndLoc).getEnd();
// In the rare case that the expansion range is a char range, EndLoc is
// ~one token too far to the right. We may fail to prune, that's OK.
if (auto E = offsetInSelFile(EndLoc))
if (*E < SpelledTokens.front().Offset)
return false;
return true;
}
@ -401,9 +411,14 @@ private:
return NoTokens;
}
// Decomposes Loc and returns the offset if the file ID is SelFile.
llvm::Optional<unsigned> offsetInSelFile(SourceLocation Loc) const {
// Decoding Loc with SM.getDecomposedLoc is relatively expensive.
// But SourceLocations for a file are numerically contiguous, so we
// can use cheap integer operations instead.
if (Loc < SelFileBounds.getBegin() || Loc >= SelFileBounds.getEnd())
return llvm::None;
// FIXME: subtracting getRawEncoding() is dubious, move this logic into SM.
return Loc.getRawEncoding() - SelFileBounds.getBegin().getRawEncoding();
}