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.

(cherry picked from commit a50d048)

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

@@ -779,6 +779,7 @@ 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)