[SpecialCaseList] Filtering Globs with matching prefix

llvm/include/llvm/Support/SpecialCaseList.h

@@ -13,7 +13,10 @@
 #define LLVM_SUPPORT_SPECIALCASELIST_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/RadixTree.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/GlobPattern.h"
@@ -162,6 +165,10 @@ class SpecialCaseList {
     };
 
     std::vector<GlobMatcher::Glob> Globs;
+
+    RadixTree<iterator_range<StringRef::const_iterator>,
+              SmallVector<const GlobMatcher::Glob *, 1>>
+        PrefixToGlob;
   };
 
   /// Represents a set of patterns and their line numbers

llvm/lib/Support/SpecialCaseList.cpp

@@ -89,14 +89,33 @@ void SpecialCaseList::GlobMatcher::preprocess(bool BySize) {
       return A.Name.size() < B.Name.size();
     });
   }
+
+  for (const auto &G : reverse(Globs)) {
+    StringRef Prefix = G.Pattern.prefix();
+
+    auto &V = PrefixToGlob.emplace(Prefix).first->second;
+    V.emplace_back(&G);
+  }
 }
 
 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))
-      return Cb(G.Name, G.LineNo);
+  if (!PrefixToGlob.empty()) {
+    for (const auto &[_, V] : PrefixToGlob.find_prefixes(Query)) {
+      for (const auto *G : V) {
+        // Each value of the map is a vector of globs sorted as from best to
+        // worst.
+        if (G->Pattern.match(Query)) {
+          Cb(G->Name, G->LineNo);
+          // As soon as we find a match in the vector we can break for the vector,
+          // but we still need to continue for other values in the map, as they
+          // may contain a better match.
+          break;
+        }
+      }
+    }
+  }
 }
 
 SpecialCaseList::Matcher::Matcher(bool UseGlobs, bool RemoveDotSlash)