java-topology/defects/cmake/patch/cmake-0004-addsource-unordered-set.patch

28 lines
1.4 KiB
Diff

diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index abc1234..def5678 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -1428,11 +1428,19 @@ cmSourceFile* cmTarget::AddSource(std::string const& src, bool before)
{
cmSourceFileLocation sfl(this->impl->Makefile, src,
cmSourceFileLocationKind::Known);
+ // Fast path: check a parallel unordered_set of source-path strings.
+ // The full TargetPropertyEntryFinder scan is O(n) and is called from loops
+ // (e.g. Unity build file iteration), producing O(n^2) overall.
+ // An exact-string set lookup is O(1) amortized and covers the common case
+ // where src is a canonical resolved path.
+ if (!this->impl->SourcePathsSet.insert(src).second) {
+ // Already present — skip the expensive find_if and WriteDirect.
+ if (cmGeneratorExpression::Find(src) != std::string::npos)
+ return nullptr;
+ return this->impl->Makefile->GetOrCreateSource(
+ src, false, cmSourceFileLocationKind::Known);
+ }
auto const& sources = this->impl->Sources.Entries;
if (std::find_if(sources.begin(), sources.end(),
TargetPropertyEntryFinder(sfl)) == sources.end()) {
this->impl->Sources.WriteDirect(
this->impl.get(), {}, cmValue(src),
before ? UsageRequirementProperty::Action::Prepend
: UsageRequirementProperty::Action::Append);
}