[Autobackout][FunctionalRegression]Revert of change: a932f9c: Make GRF selection in Pre-RA less conservative

Author: sys-igc

visa/G4_Kernel.cpp

@@ -2118,8 +2118,7 @@ unsigned G4_Kernel::getSRFInWords() {
 
 // GRF modes supported by HW
 // There must be at least one Config that is VRTEnable for each platform
-GRFMode::GRFMode(const TARGET_PLATFORM plat, Options *op)
-    : platform(plat), options(op) {
+GRFMode::GRFMode(const TARGET_PLATFORM platform, Options *op) : options(op) {
   switch (platform) {
   case Xe_XeHPSDV:
   case Xe_DG2:
@@ -2180,7 +2179,7 @@ GRFMode::GRFMode(const TARGET_PLATFORM plat, Options *op)
 unsigned GRFMode::setModeByRegPressure(unsigned maxRP, unsigned largestInputReg,
                                        bool forceGRFModeUp) {
   unsigned size = configs.size(), i = 0;
-  bool spillAllowed = getSpillThreshold() > 0;
+  bool spillAllowed = options->getuInt32Option(vISA_SpillAllowed) > 256;
   // find appropiate GRF based on reg pressure
   for (; i < size; i++) {
     if (configs[i].VRTEnable && configs[i].numGRF >= lowerBoundGRF &&
@@ -2198,22 +2197,10 @@ unsigned GRFMode::setModeByRegPressure(unsigned maxRP, unsigned largestInputReg,
           currentMode = newGRFMode < maxGRFMode ? newGRFMode : maxGRFMode;
         }
 
-        if (spillAllowed && currentMode > 0) {
-          unsigned lowerGRFNum = configs[currentMode - 1].numGRF;
-          // Select a lower GRF number in PreRA in case the register
-          // pressure computed is a bit higher (e.g. 5%) than the lower GRF
-          // config. If spills are detected, RA will still bump up the GRF
-          // number to avoid them.
-          // For example, if reg pressure is 167, we select 160GRF since
-          // we have spill threshold enabled and the diff between 167 and 160
-          // is less than 5%.
-          if ((lowerGRFNum * 1.05 >= maxRP ||
-               configs[currentMode].numGRF == getMaxGRF()) &&
-              lowerGRFNum >= (largestInputReg + 8) &&
-              lowerGRFNum >= lowerBoundGRF)
-            return configs[--currentMode].numGRF;
-        }
-        return configs[currentMode].numGRF;
+        if (spillAllowed && currentMode > 0)
+          return configs[--currentMode].numGRF;
+        else
+          return configs[currentMode].numGRF;
       }
     }
   }
@@ -2233,8 +2220,6 @@ bool GRFMode::hasLargerGRFSameThreads() const {
 
 // Get spill threshold for current GRF mode
 unsigned GRFMode::getSpillThreshold() const {
-  if (platform < Xe3)
-    return 0;
   if (configs[currentMode].numGRF == 256 &&
       options->getuInt32Option(vISA_SpillAllowed256GRF) > 0)
     return options->getuInt32Option(vISA_SpillAllowed256GRF);

visa/G4_Kernel.hpp

@@ -266,7 +266,6 @@ class GRFMode {
   unsigned lowerBoundGRF;
   unsigned upperBoundGRF;
   unsigned GRFModeUpValue;
-  const TARGET_PLATFORM platform;
   Options *options;
 };
 

visa/GraphColor.cpp

@@ -11299,20 +11299,15 @@ GlobalRA::abortOnSpill(unsigned int GRFSpillFillCount,
 
   // vISA_AbortOnSpillThreshold is defined as [0..200]
   // where 0 means abort on any spill and 200 means never abort
-  auto underSpillThreshold = [this](int numSpill, int asmCount,
-                                    GraphColor &coloring) {
+  auto underSpillThreshold = [this](int numSpill, int asmCount) {
     int threshold = std::min(
         builder.getOptions()->getuInt32Option(vISA_AbortOnSpillThreshold),
         200u);
-    unsigned spillSize = computeSpillSize(coloring.getSpilledLiveRanges());
-
-    return (numSpill * 200) < (threshold * asmCount) ||
-           spillSize < kernel.grfMode.getSpillThreshold();
+    return (numSpill * 200) < (threshold * asmCount);
   };
 
   unsigned int instNum = instCount();
-  bool isUnderThreshold =
-      underSpillThreshold(GRFSpillFillCount, instNum, coloring);
+  bool isUnderThreshold = underSpillThreshold(GRFSpillFillCount, instNum);
   isUnderThreshold = builder.getFreqInfoManager().underFreqSpillThreshold(
       coloring.getSpilledLiveRanges(), instNum, GRFSpillFillCount,
       isUnderThreshold);