Introduce Flag to Control SIMD16 drop

Diagnostics feature, ability to control SIMD16 drop by setting flag
during compilation.

Author: esukhov

IGC/Compiler/CISACodeGen/OpenCLKernelCodeGen.cpp

@@ -3469,7 +3469,7 @@ namespace IGC
 
         if (ctx->platform.getMinDispatchMode() == SIMDMode::SIMD16)
         {
-            bool abortOnSpills = ctx->platform.isCoreXE2() && (ctx->getModuleMetaData()->csInfo.forcedSIMDSize != 32);
+            bool abortOnSpills = IGC_GET_FLAG_VALUE(AllowSIMD16DropForXE2) && ctx->platform.isCoreXE2() && (ctx->getModuleMetaData()->csInfo.forcedSIMDSize != 32);
             AddCodeGenPasses(*ctx, shaders, Passes, SIMDMode::SIMD32, abortOnSpills);
             AddCodeGenPasses(*ctx, shaders, Passes, SIMDMode::SIMD16, false);
 

IGC/common/igc_flags.h

@@ -868,6 +868,7 @@ DECLARE_IGC_REGKEY(debugString, DumpRegPressureEstimateFilter, 0, "Only dump Reg
 DECLARE_IGC_REGKEY(bool, VectorizerLog, false, "Dump Vectorizer Log, usefull for analyzing vectorization issues", false)
 DECLARE_IGC_REGKEY(bool, EnableReusingXYZWStoreConstPayload, true, "Enable reusing XYZW stores const payload", false)
 DECLARE_IGC_REGKEY(bool, EnableReusingLSCStoreConstPayload,  false, "Enable reusing LSC stores const payload", false)
+DECLARE_IGC_REGKEY(bool, AllowSIMD16DropForXE2, true, "Controls the switch for XE2 simd16 drop", false)
 DECLARE_IGC_REGKEY(DWORD, RegPressureVerbocity,   0,  "Different printing types", false)
 DECLARE_IGC_REGKEY(DWORD, RetryRevertExcessiveSpillingKernelThreshold, 10000,  "Sets the threshold for Retry Manager to know which kernel is considered as Excessive Spilling and applies different set of rules", false)
 DECLARE_IGC_REGKEY(DWORD, RetryRevertExcessiveSpillingKernelCoefficient, 102,  "Sets the coefficient for Retry Manager to know whether we should revert back to a previously compiled kernel", false)