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[SourceManager] Improve getFileIDLoaded.

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Similar to getFileIDLocal patch, but for the version for load module.

Test with clangd (building AST with preamble), FileID scans in binary
search is reduced:

SemaExpr.cpp: 142K -> 137K (-3%)
FindTarget.cpp: 368K -> 343K (-6%)

Differential Revision: https://reviews.llvm.org/D135258
This commit is contained in:
Haojian Wu
2022-10-05 11:31:04 +02:00
parent e09b0589a9
commit df61bb271a
1 changed files with 18 additions and 16 deletions
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34
clang/lib/Basic/SourceManager.cpp
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@@ -869,36 +869,38 @@ FileID SourceManager::getFileIDLoaded(SourceLocation::UIntTy SLocOffset) const {
}
// Essentially the same as the local case, but the loaded array is sorted
// in the other direction.
// in the other direction (decreasing order).
// GreaterIndex is the one where the offset is greater, which is actually a
// lower index!
unsigned GreaterIndex = 0;
unsigned LessIndex = LoadedSLocEntryTable.size();
if (LastFileIDLookup.ID < 0) {
// Prune the search space.
int LastID = LastFileIDLookup.ID;
if (getLoadedSLocEntryByID(LastID).getOffset() > SLocOffset)
GreaterIndex =
(-LastID - 2) + 1; // Exclude LastID, else we would have hit the cache
else
LessIndex = -LastID - 2;
}
// First do a linear scan from the last lookup position, if possible.
unsigned I;
int LastID = LastFileIDLookup.ID;
if (LastID >= 0 || getLoadedSLocEntryByID(LastID).getOffset() < SLocOffset)
I = 0;
else
I = (-LastID - 2) + 1;
unsigned NumProbes;
bool Invalid = false;
for (NumProbes = 0; NumProbes < 8; ++NumProbes, ++I) {
for (NumProbes = 0; NumProbes < 8; ++NumProbes, ++GreaterIndex) {
// Make sure the entry is loaded!
const SrcMgr::SLocEntry &E = getLoadedSLocEntry(I, &Invalid);
const SrcMgr::SLocEntry &E = getLoadedSLocEntry(GreaterIndex, &Invalid);
if (Invalid)
return FileID(); // invalid entry.
if (E.getOffset() <= SLocOffset) {
FileID Res = FileID::get(-int(I) - 2);
FileID Res = FileID::get(-int(GreaterIndex) - 2);
LastFileIDLookup = Res;
NumLinearScans += NumProbes + 1;
return Res;
}
}
// Linear scan failed. Do the binary search. Note the reverse sorting of the
// table: GreaterIndex is the one where the offset is greater, which is
// actually a lower index!
unsigned GreaterIndex = I;
unsigned LessIndex = LoadedSLocEntryTable.size();
// Linear scan failed. Do the binary search.
NumProbes = 0;
while (true) {
++NumProbes;