From 1468b7dcde3362c19e178bb58edbee551f0b2843 Mon Sep 17 00:00:00 2001
From: Dean Michael Berris <dberris@google.com>
Date: Thu, 13 Sep 2018 09:25:42 +0000
Subject: [PATCH] [XRay] Bug fixes for FDR custom event and arg-logging

Summary:
This change has a number of fixes for FDR mode in compiler-rt along with
changes to the tooling handling the traces in llvm.

In the runtime, we do the following:

- Advance the "last record" pointer appropriately when writing the
  custom event data in the log.

- Add XRAY_NEVER_INSTRUMENT in the rewinding routine.

- When collecting the argument of functions appropriately marked, we
  should not attempt to rewind them (and reset the counts of functions
  that can be re-wound).

In the tooling, we do the following:

- Remove the state logic in BlockIndexer and instead rely on the
  presence/absence of records to indicate blocks.

- Move the verifier into a loop associated with each block.

Reviewers: mboerger, eizan

Subscribers: llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D51965

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342122 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/XRay/BlockIndexer.h |  3 ---
 lib/XRay/BlockIndexer.cpp        | 25 ++++++-------------------
 lib/XRay/Trace.cpp               |  3 +--
 3 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/include/llvm/XRay/BlockIndexer.h b/include/llvm/XRay/BlockIndexer.h
index 389e5cf47f6..46a7243685f 100644
--- a/include/llvm/XRay/BlockIndexer.h
+++ b/include/llvm/XRay/BlockIndexer.h
@@ -39,9 +39,6 @@ public:
 private:
   Index &Indices;
 
-  enum class State : unsigned { SeekExtents, ExtentsFound, ThreadIDFound };
-
-  State CurrentState = State::SeekExtents;
   Block CurrentBlock{0, 0, nullptr, {}};
 
 public:
diff --git a/lib/XRay/BlockIndexer.cpp b/lib/XRay/BlockIndexer.cpp
index e1c554aff73..98e91f7de54 100644
--- a/lib/XRay/BlockIndexer.cpp
+++ b/lib/XRay/BlockIndexer.cpp
@@ -16,22 +16,7 @@
 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,
-                          CurrentBlock.WallclockTime,
-                          std::move(CurrentBlock.Records)});
-    CurrentBlock.ProcessID = 0;
-    CurrentBlock.ThreadID = 0;
-    CurrentBlock.WallclockTime = nullptr;
-    CurrentBlock.Records = {};
-  }
-  CurrentState = State::ExtentsFound;
-  return Error::success();
-}
+Error BlockIndexer::visit(BufferExtents &) { return Error::success(); }
 
 Error BlockIndexer::visit(WallclockRecord &R) {
   CurrentBlock.Records.push_back(&R);
@@ -66,14 +51,16 @@ Error BlockIndexer::visit(PIDRecord &R) {
 }
 
 Error BlockIndexer::visit(NewBufferRecord &R) {
-  CurrentState = State::ThreadIDFound;
+  if (!CurrentBlock.Records.empty())
+    if (auto E = flush())
+      return E;
+
   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();
 }
@@ -84,7 +71,6 @@ Error BlockIndexer::visit(FunctionRecord &R) {
 }
 
 Error BlockIndexer::flush() {
-  CurrentState = State::SeekExtents;
   Index::iterator It;
   std::tie(It, std::ignore) =
       Indices.insert({{CurrentBlock.ProcessID, CurrentBlock.ThreadID}, {}});
@@ -94,6 +80,7 @@ Error BlockIndexer::flush() {
   CurrentBlock.ProcessID = 0;
   CurrentBlock.ThreadID = 0;
   CurrentBlock.Records = {};
+  CurrentBlock.WallclockTime = nullptr;
   return Error::success();
 }
 
diff --git a/lib/XRay/Trace.cpp b/lib/XRay/Trace.cpp
index 1a04b18ad9f..15cafa51bec 100644
--- a/lib/XRay/Trace.cpp
+++ b/lib/XRay/Trace.cpp
@@ -289,16 +289,15 @@ Error loadFDRLog(StringRef Data, bool IsLittleEndian,
 
   // Then we verify the consistency of the blocks.
   {
-    BlockVerifier Verifier;
     for (auto &PTB : Index) {
       auto &Blocks = PTB.second;
       for (auto &B : Blocks) {
+        BlockVerifier Verifier;
         for (auto *R : B.Records)
           if (auto E = R->apply(Verifier))
             return E;
         if (auto E = Verifier.verify())
           return E;
-        Verifier.reset();
       }
     }
   }