High Spilling Kernels are treated differently when deciding

whether to use previous kernel

High Spilling Kernels are treated differently when deciding
whether to use previous kernel. If it's a high spilling kernel,
threshold is set as an igc flag, and we have less instructions and less
spills in previous kernel (before retry) we take it instead.

Author: esukhov

IGC/Compiler/CodeGenContext.cpp

@@ -288,12 +288,19 @@ namespace IGC
             IGC_ASSERT(currentShader);
             IGC_ASSERT(previousShader);
 
+            // basically a small work around, if we have high spilling kernel on our hands, we are not afraid to use
+            // pre-retry shader, when we have less spills than retry one has
+            bool IsExcessiveSpillKernel = currentShader->m_spillSize >= IGC_GET_FLAG_VALUE(RetryRevertExcessiveSpillingKernelThreshold);
+            if (IsExcessiveSpillKernel) threshold = 1.02f;
+
             // Check if current shader spill is larger than previous shader spill
             // Threshold flag controls comparison tolerance - i.e. A threshold of 2.0 means that the
             // current shader spill must be 2x larger than previous spill to be considered "better".
             bool spillSizeBigger =
                 currentShader->m_spillSize > (unsigned int)(previousShader->m_spillSize * threshold);
 
+            llvm::errs() << " spill size: " << currentShader->m_spillSize << "\n";
+
             if (spillSizeBigger)
             {
                 // The previous shader was better, ignore any future retry compilation

IGC/common/igc_flags.h

@@ -784,6 +784,7 @@ DECLARE_IGC_REGKEY(debugString, DumpRegPressureEstimateFilter, 0, "Only dump Reg
 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(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(bool, ForceNoFP64bRegioning, false, "force regioning rules for FP and 64b FPU instructions", false)
 DECLARE_IGC_REGKEY(bool, EnableA64WA, true, "Guarantee A64 load/store addres-hi is uniform", true)
 DECLARE_IGC_REGKEY(bool, EnableSamplerSplit, false, "Split Sampler 3d message to odd and even", false)