[clang] [clang] Improve getFileIDLocal binary search. (PR #146510)

[Erich Keane via cfe-commits]

================
@@ -855,35 +857,24 @@ FileID SourceManager::getFileIDLocal(SourceLocation::UIntTy SLocOffset) const {
       break;
   }
 
-  NumProbes = 0;
-  while (true) {
-    unsigned MiddleIndex = (GreaterIndex-LessIndex)/2+LessIndex;
-    SourceLocation::UIntTy MidOffset =
-        getLocalSLocEntry(MiddleIndex).getOffset();
-
-    ++NumProbes;
-
-    // If the offset of the midpoint is too large, chop the high side of the
-    // range to the midpoint.
-    if (MidOffset > SLocOffset) {
-      GreaterIndex = MiddleIndex;
-      continue;
-    }
+  while (LessIndex < GreaterIndex) {
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erichkeane wrote:

Trying to learn this function myself... I was wondering : Did you do any benchmarking/etc on the linear search above?  Wonder if there is more perf to be grabbed out of it.

https://github.com/llvm/llvm-project/pull/146510