[SpecialCaseList] Support early return from matching (llvm#163279)

On average it saves half positive of Glob matching.

However, in real build most SpecialCaseList unmatched,
this change should not affect this case. 

To be able to do so without breaking behavior, we
need to re-order matches according precedence.

Usually it's LineNo, and it's already ordered,
but Diagnostic requires reordering by rule length.

Co-authored-by: Rahul Joshi <[email protected]>

Author: vitalybuka

clang/lib/Basic/Diagnostic.cpp

@@ -525,7 +525,8 @@ std::unique_ptr<WarningsSpecialCaseList>
 WarningsSpecialCaseList::create(const llvm::MemoryBuffer &Input,
                                 std::string &Err) {
   auto WarningSuppressionList = std::make_unique<WarningsSpecialCaseList>();
-  if (!WarningSuppressionList->createInternal(&Input, Err))
+  if (!WarningSuppressionList->createInternal(&Input, Err,
+                                              /*OrderBySize=*/true))
     return nullptr;
   return WarningSuppressionList;
 }

llvm/include/llvm/Support/SpecialCaseList.h

@@ -115,7 +115,8 @@ class SpecialCaseList {
   // classes.
   LLVM_ABI bool createInternal(const std::vector<std::string> &Paths,
                                vfs::FileSystem &VFS, std::string &Error);
-  LLVM_ABI bool createInternal(const MemoryBuffer *MB, std::string &Error);
+  LLVM_ABI bool createInternal(const MemoryBuffer *MB, std::string &Error,
+                               bool OrderBySize = false);
 
   SpecialCaseList() = default;
   SpecialCaseList(SpecialCaseList const &) = delete;
@@ -126,6 +127,8 @@ class SpecialCaseList {
   class RegexMatcher {
   public:
     LLVM_ABI Error insert(StringRef Pattern, unsigned LineNumber);
+    LLVM_ABI void preprocess(bool BySize);
+
     LLVM_ABI void
     match(StringRef Query,
           llvm::function_ref<void(StringRef Rule, unsigned LineNo)> Cb) const;
@@ -144,6 +147,8 @@ class SpecialCaseList {
   class GlobMatcher {
   public:
     LLVM_ABI Error insert(StringRef Pattern, unsigned LineNumber);
+    LLVM_ABI void preprocess(bool BySize);
+
     LLVM_ABI void
     match(StringRef Query,
           llvm::function_ref<void(StringRef Rule, unsigned LineNo)> Cb) const;
@@ -165,6 +170,7 @@ class SpecialCaseList {
     LLVM_ABI Matcher(bool UseGlobs, bool RemoveDotSlash);
 
     LLVM_ABI Error insert(StringRef Pattern, unsigned LineNumber);
+    LLVM_ABI void preprocess(bool BySize);
 
     LLVM_ABI void
     match(StringRef Query,
@@ -206,6 +212,8 @@ class SpecialCaseList {
                                        StringRef Category) const;
 
   private:
+    friend class SpecialCaseList;
+    LLVM_ABI void preprocess(bool OrderBySize);
     LLVM_ABI const SpecialCaseList::Matcher *
     findMatcher(StringRef Prefix, StringRef Category) const;
   };
@@ -222,7 +230,7 @@ class SpecialCaseList {
 
   /// Parses just-constructed SpecialCaseList entries from a memory buffer.
   LLVM_ABI bool parse(unsigned FileIdx, const MemoryBuffer *MB,
-                      std::string &Error);
+                      std::string &Error, bool OrderBySize);
 };
 
 } // namespace llvm

llvm/lib/Support/SpecialCaseList.cpp

@@ -55,12 +55,20 @@ Error SpecialCaseList::RegexMatcher::insert(StringRef Pattern,
   return Error::success();
 }
 
+void SpecialCaseList::RegexMatcher::preprocess(bool BySize) {
+  if (BySize) {
+    llvm::stable_sort(RegExes, [](const Reg &A, const Reg &B) {
+      return A.Name.size() < B.Name.size();
+    });
+  }
+}
+
 void SpecialCaseList::RegexMatcher::match(
     StringRef Query,
     llvm::function_ref<void(StringRef Rule, unsigned LineNo)> Cb) const {
   for (const auto &R : reverse(RegExes))
     if (R.Rg.match(Query))
-      Cb(R.Name, R.LineNo);
+      return Cb(R.Name, R.LineNo);
 }
 
 Error SpecialCaseList::GlobMatcher::insert(StringRef Pattern,
@@ -75,12 +83,20 @@ Error SpecialCaseList::GlobMatcher::insert(StringRef Pattern,
   return Error::success();
 }
 
+void SpecialCaseList::GlobMatcher::preprocess(bool BySize) {
+  if (BySize) {
+    llvm::stable_sort(Globs, [](const Glob &A, const Glob &B) {
+      return A.Name.size() < B.Name.size();
+    });
+  }
+}
+
 void SpecialCaseList::GlobMatcher::match(
     StringRef Query,
     llvm::function_ref<void(StringRef Rule, unsigned LineNo)> Cb) const {
   for (const auto &G : reverse(Globs))
     if (G.Pattern.match(Query))
-      Cb(G.Name, G.LineNo);
+      return Cb(G.Name, G.LineNo);
 }
 
 SpecialCaseList::Matcher::Matcher(bool UseGlobs, bool RemoveDotSlash)
@@ -91,6 +107,14 @@ SpecialCaseList::Matcher::Matcher(bool UseGlobs, bool RemoveDotSlash)
     M.emplace<RegexMatcher>();
 }
 
+Error SpecialCaseList::Matcher::insert(StringRef Pattern, unsigned LineNumber) {
+  return std::visit([&](auto &V) { return V.insert(Pattern, LineNumber); }, M);
+}
+
+LLVM_ABI void SpecialCaseList::Matcher::preprocess(bool BySize) {
+  return std::visit([&](auto &V) { return V.preprocess(BySize); }, M);
+}
+
 void SpecialCaseList::Matcher::match(
     StringRef Query,
     llvm::function_ref<void(StringRef Rule, unsigned LineNo)> Cb) const {
@@ -99,10 +123,6 @@ void SpecialCaseList::Matcher::match(
   return std::visit([&](auto &V) { return V.match(Query, Cb); }, M);
 }
 
-Error SpecialCaseList::Matcher::insert(StringRef Pattern, unsigned LineNumber) {
-  return std::visit([&](auto &V) { return V.insert(Pattern, LineNumber); }, M);
-}
-
 // TODO: Refactor this to return Expected<...>
 std::unique_ptr<SpecialCaseList>
 SpecialCaseList::create(const std::vector<std::string> &Paths,
@@ -141,17 +161,17 @@ bool SpecialCaseList::createInternal(const std::vector<std::string> &Paths,
       return false;
     }
     std::string ParseError;
-    if (!parse(i, FileOrErr.get().get(), ParseError)) {
+    if (!parse(i, FileOrErr.get().get(), ParseError, /*OrderBySize=*/false)) {
       Error = (Twine("error parsing file '") + Path + "': " + ParseError).str();
       return false;
     }
   }
   return true;
 }
 
-bool SpecialCaseList::createInternal(const MemoryBuffer *MB,
-                                     std::string &Error) {
-  if (!parse(0, MB, Error))
+bool SpecialCaseList::createInternal(const MemoryBuffer *MB, std::string &Error,
+                                     bool OrderBySize) {
+  if (!parse(0, MB, Error, OrderBySize))
     return false;
   return true;
 }
@@ -174,7 +194,7 @@ SpecialCaseList::addSection(StringRef SectionStr, unsigned FileNo,
 }
 
 bool SpecialCaseList::parse(unsigned FileIdx, const MemoryBuffer *MB,
-                            std::string &Error) {
+                            std::string &Error, bool OrderBySize) {
   unsigned long long Version = 2;
 
   StringRef Header = MB->getBuffer();
@@ -246,6 +266,10 @@ bool SpecialCaseList::parse(unsigned FileIdx, const MemoryBuffer *MB,
       return false;
     }
   }
+
+  for (Section &S : Sections)
+    S.preprocess(OrderBySize);
+
   return true;
 }
 
@@ -283,6 +307,13 @@ SpecialCaseList::Section::findMatcher(StringRef Prefix,
   return &II->second;
 }
 
+LLVM_ABI void SpecialCaseList::Section::preprocess(bool OrderBySize) {
+  SectionMatcher.preprocess(false);
+  for (auto &[K1, E] : Entries)
+    for (auto &[K2, M] : E)
+      M.preprocess(OrderBySize);
+}
+
 unsigned SpecialCaseList::Section::getLastMatch(StringRef Prefix,
                                                 StringRef Query,
                                                 StringRef Category) const {