Disable MTP when stack calls are present.

Change-Id: Ib7dd8da78dc8f443e01302b8baa3623da58b4823

Author: dlei6g

IGC/Compiler/CISACodeGen/CISABuilder.cpp

@@ -3989,7 +3989,7 @@ namespace IGC
         }
 
         if ((context->type == ShaderType::OPENCL_SHADER || context->type == ShaderType::COMPUTE_SHADER) &&
-            VISAPlatform >= GENX_SKL && IGC_IS_FLAG_ENABLED(EnablePreemption) && !hasStackCall && !context->m_enableFunctionPointer)
+            VISAPlatform >= GENX_SKL && IGC_IS_FLAG_ENABLED(EnablePreemption) && !hasStackCall)
         {
             SaveOption(vISA_enablePreemption, true);
         }

IGC/Compiler/CISACodeGen/EmitVISAPass.cpp

@@ -732,6 +732,14 @@ bool EmitPass::runOnFunction(llvm::Function& F)
         }
     }
 
+    // Temp WA to disable MTP when stack calls are present
+    // TODO: Remove when VISA is fixed to copy R0 to dedicated register, so R0 contents won't be corrupted by MTP
+    if (m_currShader->GetShaderType() == ShaderType::OPENCL_SHADER && hasStackCall)
+    {
+        COpenCLKernel* kernel = static_cast<COpenCLKernel*>(m_currShader);
+        kernel->SetDisableMidthreadPreemption();
+    }
+
     if (m_SimdMode == SIMDMode::SIMD16 &&
         this->m_ShaderMode == ShaderDispatchMode::NOT_APPLICABLE &&
         IsStage1BestPerf(m_pCtx->m_CgFlag, m_pCtx->m_StagingCtx))