Honor max GRF set by IGC

intel · Feb 22, 2025 · d613057 · d613057
1 parent d4a5cd0
commit d613057
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Showing 5 changed files with 39 additions and 7 deletions.
diff --git a/visa/G4_Kernel.cpp b/visa/G4_Kernel.cpp
@@ -635,15 +635,16 @@ bool G4_Kernel::updateKernelToLargerGRF() {
 //
 // Updates kernel's related structures based on register pressure
 //
-void G4_Kernel::updateKernelByRegPressure(unsigned regPressure) {
+void G4_Kernel::updateKernelByRegPressure(unsigned regPressure,
+                                          bool forceGRFModeUp) {
   unsigned largestInputReg = getLargestInputRegister();
   if (m_kernelAttrs->isKernelAttrSet(Attributes::ATTR_MaxRegThreadDispatch)) {
     unsigned maxRegPayloadDispatch = m_kernelAttrs->getInt32KernelAttr(
         Attributes::ATTR_MaxRegThreadDispatch);
     largestInputReg = std::max(largestInputReg, maxRegPayloadDispatch);
   }
 
-  unsigned newGRF = grfMode.setModeByRegPressure(regPressure, largestInputReg);
+  unsigned newGRF = grfMode.setModeByRegPressure(regPressure, largestInputReg, forceGRFModeUp);
 
   if (newGRF == numRegTotal)
     return;
@@ -2167,10 +2168,15 @@ GRFMode::GRFMode(const TARGET_PLATFORM platform, Options *op) : options(op) {
   unsigned maxGRF = op->getuInt32Option(vISA_MaxGRFNum);
   upperBoundGRF = maxGRF > 0 ? maxGRF : configs.back().numGRF;
   vISA_ASSERT(isValidNumGRFs(upperBoundGRF), "Invalid upper bound for GRF number");
+
+  // Select higher GRF
+  GRFModeUpValue = op->getuInt32Option(vISA_ForceGRFModeUp);
+  vISA_ASSERT(GRFModeUpValue >= 0 && GRFModeUpValue <= configs.size(),
+              "Invalid value for selecting a higher GRF mode");
 }
 
-unsigned GRFMode::setModeByRegPressure(unsigned maxRP,
-                                       unsigned largestInputReg) {
+unsigned GRFMode::setModeByRegPressure(unsigned maxRP, unsigned largestInputReg,
+                                       bool forceGRFModeUp) {
   unsigned size = configs.size(), i = 0;
   bool spillAllowed = 0;
   spillAllowed = options->getuInt32Option(vISA_SpillAllowed) > 256;
@@ -2184,6 +2190,13 @@ unsigned GRFMode::setModeByRegPressure(unsigned maxRP,
           // those blocked for kernel input. This helps cases
           // where an 8 GRF variable shows up in entry BB.
           (largestInputReg + 8) <= configs[i].numGRF) {
+        if (forceGRFModeUp && GRFModeUpValue > 0) {
+          // Check if user is force a higher GRF mode
+          unsigned newGRFMode = currentMode + GRFModeUpValue;
+          unsigned maxGRFMode = getMaxGRFMode();
+          currentMode = newGRFMode < maxGRFMode ? newGRFMode : maxGRFMode;
+        }
+
         if (spillAllowed && currentMode > 0)
           return configs[--currentMode].numGRF;
         else

diff --git a/visa/G4_Kernel.hpp b/visa/G4_Kernel.hpp
@@ -152,7 +152,8 @@ class GRFMode {
     return iter != configs.end();
   }
 
-  unsigned setModeByRegPressure(unsigned maxRP, unsigned largestInputReg);
+  unsigned setModeByRegPressure(unsigned maxRP, unsigned largestInputReg,
+                                bool forceGRFModedUp = false);
   bool hasLargerGRFSameThreads() const;
 
   unsigned getNumGRF() const { return configs[currentMode].numGRF; }
@@ -189,6 +190,14 @@ class GRFMode {
     return found->numGRF;
   }
 
+  unsigned getMaxGRFMode() const {
+    auto found =
+        std::find_if(configs.rbegin(), configs.rend(), [this](const Config &c) {
+          return c.VRTEnable && c.numGRF <= upperBoundGRF;
+        });
+    return configs.size() - std::distance(configs.rbegin(), found) - 1;
+  }
+
   // Get GRF number for initial kernel creation
   unsigned getInitalGRFNum() const {
     // Max GRF number is used when GRF selection is enabled.
@@ -255,6 +264,7 @@ class GRFMode {
   unsigned currentMode;
   unsigned lowerBoundGRF;
   unsigned upperBoundGRF;
+  unsigned GRFModeUpValue;
   Options *options;
 };
 
@@ -712,7 +722,8 @@ class G4_Kernel {
   const char *getName() const { return name; }
 
   bool updateKernelToLargerGRF();
-  void updateKernelByRegPressure(unsigned regPressure);
+  void updateKernelByRegPressure(unsigned regPressure,
+                                 bool forceGRFModeUp = false);
   bool updateKernelFromNumGRFAttr();
 
   void evalAddrExp();

diff --git a/visa/LocalScheduler/G4_Sched.cpp b/visa/LocalScheduler/G4_Sched.cpp
@@ -747,7 +747,7 @@ bool preRA_Scheduler::runWithGRFSelection(unsigned &KernelPressure) {
     KernelPressure = rp.getMaxRP();
   }
 
-  kernel.updateKernelByRegPressure(KernelPressure);
+  kernel.updateKernelByRegPressure(KernelPressure, true);
 
   return Changed;
 }

diff --git a/visa/Optimizer.h b/visa/Optimizer.h
@@ -157,7 +157,10 @@ class Optimizer {
     unsigned KernelPressure = 0;
     preRA_Scheduler Sched(kernel);
     if (kernel.useAutoGRFSelection()) {
+      unsigned InitialGRFNumber = kernel.getNumRegTotal();
       Sched.runWithGRFSelection(KernelPressure);
+      if (InitialGRFNumber != kernel.getNumRegTotal())
+        Sched.run(KernelPressure);
     } else {
       Sched.run(KernelPressure);
     }

diff --git a/visa/include/VISAOptionsDefs.h b/visa/include/VISAOptionsDefs.h
@@ -168,6 +168,11 @@ DEF_VISA_OPTION(
     "Spill size allowed without increasing GRF number in VRT."
     "0 means VRT will always bump up the GRF number to avoid spills",
     256)
+DEF_VISA_OPTION(vISA_ForceGRFModeUp, ET_INT32, "-forceGRFModeUp",
+                "USAGE: -forceGRFModeUp <k>.\n"
+                "Set the GRF mode k higher than the one selected by default"
+                "heuristics. 0 means no increase in GRF mode.",
+                0)
 DEF_VISA_OPTION(vISA_ScalarPipe, ET_INT32, "-scalarPipe",
                 "USAGE: -scalarPipe <num>\n", 0)
 DEF_VISA_OPTION(vISA_LVN, ET_BOOL, "-nolvn", UNUSED, true)