[SpecialCaseList] Flip RadixTree key order

[vitalybuka]

The RadixTree key order was Prefix then Suffix. This commit changes the
order to Suffix then Prefix. Assuming that, especially in case of
"src:", suffixes are often more diverse than prefixes. So filtering by
suffix first should be more efficient.

No noticeable improvement on benchmarks:

https://gist.github.com/vitalybuka/d6d394071a4d540a50a119f317bd4e5a

[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Vitaly Buka (vitalybuka)

Changes

The RadixTree key order was Prefix then Suffix. This commit changes the
order to Suffix then Prefix. Assuming that, especially in case of
"src:", suffixes are often more diverse than prefixes. So filtering by
suffix first should be more efficient.

---

Full diff: https://github.com/llvm/llvm-project/pull/164544.diff

2 Files Affected:

• (modified) llvm/include/llvm/Support/SpecialCaseList.h (+3-3)
• (modified) llvm/lib/Support/SpecialCaseList.cpp (+6-5)

diff --git a/llvm/include/llvm/Support/SpecialCaseList.h b/llvm/include/llvm/Support/SpecialCaseList.h
index 471f8e779fa24..c077f8857c9c8 100644
--- a/llvm/include/llvm/Support/SpecialCaseList.h
+++ b/llvm/include/llvm/Support/SpecialCaseList.h
@@ -166,10 +166,10 @@ class SpecialCaseList {
 
     std::vector<GlobMatcher::Glob> Globs;
 
-    RadixTree<iterator_range<StringRef::const_iterator>,
-              RadixTree<iterator_range<StringRef::const_reverse_iterator>,
+    RadixTree<iterator_range<StringRef::const_reverse_iterator>,
+              RadixTree<iterator_range<StringRef::const_iterator>,
                         SmallVector<const GlobMatcher::Glob *, 1>>>
-        PrefixSuffixToGlob;
+        SuffixPrefixToGlob;
   };
 
   /// Represents a set of patterns and their line numbers
diff --git a/llvm/lib/Support/SpecialCaseList.cpp b/llvm/lib/Support/SpecialCaseList.cpp
index 9bd1c199695d1..15367afd91e72 100644
--- a/llvm/lib/Support/SpecialCaseList.cpp
+++ b/llvm/lib/Support/SpecialCaseList.cpp
@@ -94,8 +94,8 @@ void SpecialCaseList::GlobMatcher::preprocess(bool BySize) {
     StringRef Prefix = G.Pattern.prefix();
     StringRef Suffix = G.Pattern.suffix();
 
-    auto &SToGlob = PrefixSuffixToGlob.emplace(Prefix).first->second;
-    auto &V = SToGlob.emplace(reverse(Suffix)).first->second;
+    auto &PToGlob = SuffixPrefixToGlob.emplace(reverse(Suffix)).first->second;
+    auto &V = PToGlob.emplace(Prefix).first->second;
     V.emplace_back(&G);
   }
 }
@@ -103,9 +103,10 @@ void SpecialCaseList::GlobMatcher::preprocess(bool BySize) {
 void SpecialCaseList::GlobMatcher::match(
     StringRef Query,
     llvm::function_ref<void(StringRef Rule, unsigned LineNo)> Cb) const {
-  if (!PrefixSuffixToGlob.empty()) {
-    for (const auto &[_, SToGlob] : PrefixSuffixToGlob.find_prefixes(Query)) {
-      for (const auto &[_, V] : SToGlob.find_prefixes(reverse(Query))) {
+  if (!SuffixPrefixToGlob.empty()) {
+    for (const auto &[_, PToGlob] :
+         SuffixPrefixToGlob.find_prefixes(reverse(Query))) {
+      for (const auto &[_, V] : PToGlob.find_prefixes(Query)) {
         for (const auto *G : reverse(V)) {
           if (G->Pattern.match(Query)) {
             Cb(G->Name, G->LineNo);