add a trivial line # cache to SourceMgr to make repeated queries to
FindLineNumber much faster when in sequence.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78693 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/SourceMgr.cpp b/lib/Support/SourceMgr.cpp
index 6b0d55c..4b93f7f 100644
--- a/lib/Support/SourceMgr.cpp
+++ b/lib/Support/SourceMgr.cpp
@@ -18,7 +18,24 @@
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
+namespace {
+ struct LineNoCacheTy {
+ int LastQueryBufferID;
+ const char *LastQuery;
+ unsigned LineNoOfQuery;
+ };
+}
+
+static LineNoCacheTy *getCache(void *Ptr) {
+ return (LineNoCacheTy*)Ptr;
+}
+
+
SourceMgr::~SourceMgr() {
+ // Delete the line # cache if allocated.
+ if (LineNoCacheTy *Cache = getCache(LineNoCache))
+ delete Cache;
+
while (!Buffers.empty()) {
delete Buffers.back().Buffer;
Buffers.pop_back();
@@ -71,8 +88,31 @@
const char *Ptr = Buff->getBufferStart();
+ // If we have a line number cache, and if the query is to a later point in the
+ // same file, start searching from the last query location. This optimizes
+ // for the case when multiple diagnostics come out of one file in order.
+ if (LineNoCacheTy *Cache = getCache(LineNoCache))
+ if (Cache->LastQueryBufferID == BufferID &&
+ Cache->LastQuery <= Loc.getPointer()) {
+ Ptr = Cache->LastQuery;
+ LineNo = Cache->LineNoOfQuery;
+ }
+
+ // Scan for the location being queried, keeping track of the number of lines
+ // we see.
for (; SMLoc::getFromPointer(Ptr) != Loc; ++Ptr)
if (*Ptr == '\n') ++LineNo;
+
+
+ // Allocate the line number cache if it doesn't exist.
+ if (LineNoCache == 0)
+ LineNoCache = new LineNoCacheTy();
+
+ // Update the line # cache.
+ LineNoCacheTy &Cache = *getCache(LineNoCache);
+ Cache.LastQueryBufferID = BufferID;
+ Cache.LastQuery = Ptr;
+ Cache.LineNoOfQuery = LineNo;
return LineNo;
}