Enable symbols in the JIT for the Intel Vtune profiler (#830)

* Enable helpful symbols in the JIT for Intel Vtune profiler

* Bump which compiler SPI uses

Author: lgritz

site/spi/Makefile-bits

@@ -18,7 +18,7 @@ ifeq ($(SP_OS), rhel7)
 
     ## If not overridden, here is our preferred LLVM installation
     ## (may be changed as new versions are rolled out to the facility)
-    LLVM_DIRECTORY ?= /shots/spi/home/lib/arnold/rhel7/llvm_5.0.0
+    LLVM_DIRECTORY ?= /shots/spi/home/lib/arnold/rhel7/llvm_5.0.1_rc2
 
     # A variety of tags can be used to try specific versions of gcc or
     # clang from the site-specific places we have installed them.
@@ -28,8 +28,8 @@ ifeq ($(SP_OS), rhel7)
            -DCMAKE_CXX_COMPILER=/shots/spi/home/lib/arnold/rhel7/llvm_4.0_final/bin/clang++
     else ifeq (${COMPILER}, clang5)
         MY_CMAKE_FLAGS += \
-           -DCMAKE_C_COMPILER=/shots/spi/home/lib/arnold/rhel7/llvm_5.0.0/bin/clang \
-           -DCMAKE_CXX_COMPILER=/shots/spi/home/lib/arnold/rhel7/llvm_5.0.0/bin/clang++
+           -DCMAKE_C_COMPILER=/shots/spi/home/lib/arnold/rhel7/llvm_5.0.1_rc2/bin/clang \
+           -DCMAKE_CXX_COMPILER=/shots/spi/home/lib/arnold/rhel7/llvm_5.0.1_rc2/bin/clang++
     else ifeq (${COMPILER},clang)
         MY_CMAKE_FLAGS += -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
     else ifeq (${COMPILER}, gcc490)

src/liboslexec/llvm_util.cpp

@@ -61,6 +61,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <llvm/Support/ManagedStatic.h>
 #include <llvm/Support/MemoryBuffer.h>
 #include <llvm/ExecutionEngine/GenericValue.h>
+#include <llvm/ExecutionEngine/JITEventListener.h>
 #include <llvm/ExecutionEngine/MCJIT.h>
 #include <llvm/Support/raw_ostream.h>
 #include <llvm/Support/TargetSelect.h>
@@ -449,6 +450,17 @@ LLVM_Util::make_jit_execengine (std::string *err)
     if (! m_llvm_exec)
         return NULL;
 
+    // These magic lines will make it so that enough symbol information
+    // is injected so that running vtune will kinda tell you which shaders
+    // you're in, and sometimes which function (only for functions that don't
+    // get inlined. There doesn't seem to be any perf hit from this, either
+    // in code quality or JIT time. It is only enabled, however, if your copy
+    // of LLVM was build with -DLLVM_USE_INTEL_JITEVENTS=ON, otherwise
+    // createIntelJITEventListener() is a stub that just returns nullptr.
+    auto vtuneProfiler = llvm::JITEventListener::createIntelJITEventListener();
+    if (vtuneProfiler)
+        m_llvm_exec->RegisterJITEventListener (vtuneProfiler);
+
     // Force it to JIT as soon as we ask it for the code pointer,
     // don't take any chances that it might JIT lazily, since we
     // will be stealing the JIT code memory from under its nose and