From 66581a0a1d105d69e96a2a46ed4d74745864dd16 Mon Sep 17 00:00:00 2001
From: "Yates, Brandon" <brandon.yates@intel.com>
Date: Mon, 12 Dec 2022 22:18:52 +0000
Subject: [PATCH] L0 Debug - Avoid SSAH lookup when no threads are stopped

During async thread event processing, it was possible to
read SSAH before any threads stopped and before it was
resident resulting in an assert. This is both a fix for
assertion and minor optimization.

Signed-off-by: Yates, Brandon <brandon.yates@intel.com>
---
 .../tools/source/debug/debug_session_imp.cpp    |  3 +++
 .../sources/debug/debug_session_tests.cpp       | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/level_zero/tools/source/debug/debug_session_imp.cpp b/level_zero/tools/source/debug/debug_session_imp.cpp
index a0546e0588..68822856db 100644
--- a/level_zero/tools/source/debug/debug_session_imp.cpp
+++ b/level_zero/tools/source/debug/debug_session_imp.cpp
@@ -745,6 +745,9 @@ bool DebugSessionImp::isForceExceptionOrForceExternalHaltOnlyExceptionReason(uin
 
 void DebugSessionImp::fillResumeAndStoppedThreadsFromNewlyStopped(std::vector<EuThread::ThreadId> &resumeThreads, std::vector<EuThread::ThreadId> &stoppedThreadsToReport) {
 
+    if (newlyStoppedThreads.empty()) {
+        return;
+    }
     const auto regSize = std::max(getRegisterSize(ZET_DEBUG_REGSET_TYPE_CR_INTEL_GPU), 64u);
     auto reg = std::make_unique<uint32_t[]>(regSize / sizeof(uint32_t));
 
diff --git a/level_zero/tools/test/unit_tests/sources/debug/debug_session_tests.cpp b/level_zero/tools/test/unit_tests/sources/debug/debug_session_tests.cpp
index b018dec79a..433976ed2c 100644
--- a/level_zero/tools/test/unit_tests/sources/debug/debug_session_tests.cpp
+++ b/level_zero/tools/test/unit_tests/sources/debug/debug_session_tests.cpp
@@ -501,6 +501,23 @@ TEST(DebugSessionTest, givenStoppedThreadsWhenFillingResumeAndStoppedThreadsFrom
     }
 }
 
+TEST(DebugSessionTest, givenNoThreadsStoppedWhenCallingfillResumeAndStoppedThreadsFromNewlyStoppedThenReadStateSaveAreaNotCalled) {
+    zet_debug_config_t config = {};
+    config.pid = 0x1234;
+    auto hwInfo = *NEO::defaultHwInfo.get();
+
+    NEO::MockDevice *neoDevice(NEO::MockDevice::createWithNewExecutionEnvironment<NEO::MockDevice>(&hwInfo, 0));
+    Mock<L0::DeviceImp> deviceImp(neoDevice, neoDevice->getExecutionEnvironment());
+
+    auto sessionMock = std::make_unique<MockDebugSession>(config, &deviceImp);
+    std::vector<EuThread::ThreadId> resumeThreads;
+    std::vector<EuThread::ThreadId> stoppedThreads;
+
+    sessionMock->fillResumeAndStoppedThreadsFromNewlyStopped(resumeThreads, stoppedThreads);
+
+    EXPECT_EQ(0u, sessionMock->readStateSaveAreaHeaderCalled);
+}
+
 TEST(DebugSessionTest, givenThreadsToResumeWhenResumeAccidentallyStoppedThreadsCalledThenThreadsResumed) {
     class InternalMockDebugSession : public MockDebugSession {
       public: