[NFC][SpecialCaseList] Convert preprocess into LazyInit (#167281)

Currently SpecialCaseList created at least twice, one on by `Driver`, for diagnostics only, and then the real one by the `ASTContext`. Also, deppending on enabled sanitizers, not all sections will be used. In both cases there is unnecessary RadixTree construction. This patch changes `GlobMatcher` to do initialization lazily only when needed. And remove empty one from `RegexMatcher`. This saves saves 0.5% of clang time building large project.

Author: vitalybuka

llvm/lib/Support/SpecialCaseList.cpp

@@ -20,6 +20,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/GlobPattern.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -42,10 +43,9 @@ namespace {
 class RegexMatcher {
 public:
  Error insert(StringRef Pattern, unsigned LineNumber);
- void preprocess();
-
  unsigned match(StringRef Query) const;
 
+private:
  struct Reg {
  Reg(StringRef Name, unsigned LineNo, Regex &&Rg)
  : Name(Name), LineNo(LineNo), Rg(std::move(Rg)) {}
@@ -60,10 +60,9 @@ class RegexMatcher {
 class GlobMatcher {
 public:
  Error insert(StringRef Pattern, unsigned LineNumber);
- void preprocess();
-
  unsigned match(StringRef Query) const;
 
+private:
  struct Glob {
  Glob(StringRef Name, unsigned LineNo, GlobPattern &&Pattern)
  : Name(Name), LineNo(LineNo), Pattern(std::move(Pattern)) {}
@@ -72,15 +71,20 @@ class GlobMatcher {
  GlobPattern Pattern;
  };
 
+ void LazyInit() const;
+
  std::vector<GlobMatcher::Glob> Globs;
 
- RadixTree<iterator_range<StringRef::const_iterator>,
- RadixTree<iterator_range<StringRef::const_reverse_iterator>,
- SmallVector<int, 1>>>
+ mutable RadixTree<iterator_range<StringRef::const_iterator>,
+  RadixTree<iterator_range<StringRef::const_reverse_iterator>,
+  SmallVector<int, 1>>>
  PrefixSuffixToGlob;
 
- RadixTree<iterator_range<StringRef::const_iterator>, SmallVector<int, 1>>
+ mutable RadixTree<iterator_range<StringRef::const_iterator>,
+ SmallVector<int, 1>>
  SubstrToGlob;
+
+ mutable bool Initialized = false;
 };
 
 /// Represents a set of patterns and their line numbers
@@ -89,7 +93,6 @@ class Matcher {
  Matcher(bool UseGlobs, bool RemoveDotSlash);
 
  Error insert(StringRef Pattern, unsigned LineNumber);
- void preprocess();
  unsigned match(StringRef Query) const;
 
  bool matchAny(StringRef Query) const { return match(Query); }
@@ -122,8 +125,6 @@ Error RegexMatcher::insert(StringRef Pattern, unsigned LineNumber) {
  return Error::success();
 }
 
-void RegexMatcher::preprocess() {}
-
 unsigned RegexMatcher::match(StringRef Query) const {
  for (const auto &R : reverse(RegExes))
  if (R.Rg.match(Query))
@@ -142,7 +143,10 @@ Error GlobMatcher::insert(StringRef Pattern, unsigned LineNumber) {
  return Error::success();
 }
 
-void GlobMatcher::preprocess() {
+void GlobMatcher::LazyInit() const {
+ if (LLVM_LIKELY(Initialized))
+ return;
+ Initialized = true;
  for (const auto &[Idx, G] : enumerate(Globs)) {
  StringRef Prefix = G.Pattern.prefix();
  StringRef Suffix = G.Pattern.suffix();
@@ -167,6 +171,8 @@ void GlobMatcher::preprocess() {
 }
 
 unsigned GlobMatcher::match(StringRef Query) const {
+ LazyInit();
+
  int Best = -1;
  if (!PrefixSuffixToGlob.empty()) {
  for (const auto &[_, SToGlob] : PrefixSuffixToGlob.find_prefixes(Query)) {
@@ -224,10 +230,6 @@ Error Matcher::insert(StringRef Pattern, unsigned LineNumber) {
  return std::visit([&](auto &V) { return V.insert(Pattern, LineNumber); }, M);
 }
 
-void Matcher::preprocess() {
- return std::visit([&](auto &V) { return V.preprocess(); }, M);
-}
-
 unsigned Matcher::match(StringRef Query) const {
  if (RemoveDotSlash)
  Query = llvm::sys::path::remove_leading_dotslash(Query);
@@ -237,7 +239,6 @@ unsigned Matcher::match(StringRef Query) const {
 
 class SpecialCaseList::Section::SectionImpl {
 public:
- void preprocess();
  const Matcher *findMatcher(StringRef Prefix, StringRef Category) const;
 
  using SectionEntries = StringMap<StringMap<Matcher>>;
@@ -395,9 +396,6 @@ bool SpecialCaseList::parse(unsigned FileIdx, const MemoryBuffer *MB,
  }
  }
 
- for (Section &S : Sections)
- S.Impl->preprocess();
-
  return true;
 }
 
@@ -448,13 +446,6 @@ SpecialCaseList::Section::SectionImpl::findMatcher(StringRef Prefix,
  return &II->second;
 }
 
-void SpecialCaseList::Section::SectionImpl::preprocess() {
- SectionMatcher.preprocess();
- for (auto &[K1, E] : Entries)
- for (auto &[K2, M] : E)
- M.preprocess();
-}
-
 unsigned SpecialCaseList::Section::getLastMatch(StringRef Prefix,
  StringRef Query,
  StringRef Category) const {