[XRay] Add a BlockIndexer visitor for FDR Records.

Summary:
This change adds a `BlockIndexer` type which maintains pointers to
records that belong to the same process+thread pairs. The indexing
happens with order of appearance of records as they are visited.

This version of the indexer currently only supports FDR version 3 logs,
which contain `BufferExtent` records. We will add support for v2 and v1
logs in follow-up patches.

This is another part of D50441.

Reviewers: eizan, kpw, mboerger

Reviewed By: mboerger

Subscribers: mboerger, mgorny, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D51673

llvm-svn: 341518

2 files changed, 98 insertions, 0 deletions

diff --git a/llvm/lib/XRay/BlockIndexer.cpp b/llvm/lib/XRay/BlockIndexer.cpp
new file mode 100644
index 00000000000..4b76ad9ecdc
--- /dev/null
+++ b/llvm/lib/XRay/BlockIndexer.cpp
@@ -0,0 +1,97 @@
+//===- BlockIndexer.cpp - FDR Block Indexing VIsitor ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// An implementation of the RecordVisitor which generates a mapping between a
+// thread and a range of records representing a block.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/XRay/BlockIndexer.h"
+
+namespace llvm {
+namespace xray {
+
+Error BlockIndexer::visit(BufferExtents &) {
+  if (CurrentState == State::ThreadIDFound) {
+    Index::iterator It;
+    std::tie(It, std::ignore) =
+        Indices.insert({{CurrentBlock.ProcessID, CurrentBlock.ThreadID}, {}});
+    It->second.push_back({CurrentBlock.ProcessID, CurrentBlock.ThreadID,
+                          std::move(CurrentBlock.Records)});
+    CurrentBlock.ProcessID = 0;
+    CurrentBlock.ThreadID = 0;
+    CurrentBlock.Records = {};
+  }
+  CurrentState = State::ExtentsFound;
+  return Error::success();
+}
+
+Error BlockIndexer::visit(WallclockRecord &R) {
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(NewCPUIDRecord &R) {
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(TSCWrapRecord &R) {
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(CustomEventRecord &R) {
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(CallArgRecord &R) {
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+};
+
+Error BlockIndexer::visit(PIDRecord &R) {
+  CurrentBlock.ProcessID = R.pid();
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(NewBufferRecord &R) {
+  CurrentState = State::ThreadIDFound;
+  CurrentBlock.ThreadID = R.tid();
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(EndBufferRecord &R) {
+  CurrentState = State::SeekExtents;
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::visit(FunctionRecord &R) {
+  CurrentBlock.Records.push_back(&R);
+  return Error::success();
+}
+
+Error BlockIndexer::flush() {
+  CurrentState = State::SeekExtents;
+  Index::iterator It;
+  std::tie(It, std::ignore) =
+      Indices.insert({{CurrentBlock.ProcessID, CurrentBlock.ThreadID}, {}});
+  It->second.push_back({CurrentBlock.ProcessID, CurrentBlock.ThreadID,
+                        std::move(CurrentBlock.Records)});
+  CurrentBlock.ProcessID = 0;
+  CurrentBlock.ThreadID = 0;
+  CurrentBlock.Records = {};
+  return Error::success();
+}
+
+} // namespace xray
+} // namespace llvm
diff --git a/llvm/lib/XRay/CMakeLists.txt b/llvm/lib/XRay/CMakeLists.txt
index 26e12ed73f3..ab6e0373c9e 100644
--- a/llvm/lib/XRay/CMakeLists.txt
+++ b/llvm/lib/XRay/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_llvm_library(LLVMXRay
+  BlockIndexer.cpp
   FDRRecordProducer.cpp
   FDRRecords.cpp
   FDRTraceWriter.cpp