[PATCH] D97320: Use a fast path when initializing LineOffsetMapping

[serge via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG80e8efd563fd: Use a fast path when initializing LineOffsetMapping (authored by serge-sans-paille).
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D97320/new/

https://reviews.llvm.org/D97320

Files:
  clang/lib/Basic/SourceManager.cpp


Index: clang/lib/Basic/SourceManager.cpp
===================================================================
--- clang/lib/Basic/SourceManager.cpp
+++ clang/lib/Basic/SourceManager.cpp
@@ -1270,13 +1270,16 @@
   const std::size_t BufLen = End - Buf;
   unsigned I = 0;
   while (I < BufLen) {
-    if (Buf[I] == '\n') {
-      LineOffsets.push_back(I + 1);
-    } else if (Buf[I] == '\r') {
-      // If this is \r\n, skip both characters.
-      if (I + 1 < BufLen && Buf[I + 1] == '\n')
-        ++I;
-      LineOffsets.push_back(I + 1);
+    // Use a fast check to catch both newlines
+    if (LLVM_UNLIKELY(Buf[I] <= std::max('\n', '\r'))) {
+      if (Buf[I] == '\n') {
+        LineOffsets.push_back(I + 1);
+      } else if (Buf[I] == '\r') {
+        // If this is \r\n, skip both characters.
+        if (I + 1 < BufLen && Buf[I + 1] == '\n')
+          ++I;
+        LineOffsets.push_back(I + 1);
+      }
     }
     ++I;
   }


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