Fix race-condition and visual artifacts issues (#4152)

* Fix race-condition and visual artifacts issues

In PerformanceProfiler::getProfiler() we return a static object
for the profiler implementation, this is not thread-safe, so change
it to thead_local.

There is still some visual artifacts when using slang as the shading
language. We don't know the root cause yet, but found out it's related
to our loop inversion algorithm. So stage this feature for now, and turn
it into an internal option and default off. We will re-enable it after
more investigation on this optimization.

File an new issue 4151 to track it.

* Add '-loop-inversion' to the few tests

1 files changed, 4 insertions, 2 deletions

diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp
index 429660cac..9de1833a0 100644
--- a/source/slang/slang-lower-to-ir.cpp
+++ b/source/slang/slang-lower-to-ir.cpp
@@ -10839,8 +10839,10 @@ RefPtr<IRModule> generateIRForTranslationUnit(
     // - If sccp is unable to eliminate the outer 'if' then we end up with
     //   duplicated code the the conditional value. Users don't tend to put
     //   huge gobs of code in the conditional expression in loops however.
-
-    invertLoops(module);
+    if (compileRequest->getLinkage()->m_optionSet.getBoolOption(CompilerOptionName::LoopInversion))
+    {
+        invertLoops(module);
+    }
 
     // Next, attempt to promote local variables to SSA
     // temporaries and do basic simplifications.