When assume-uniform, always promote the array to register

Author: Gang Y Chen

IGC/Compiler/CISACodeGen/AnnotateUniformAllocas.cpp

@@ -84,6 +84,7 @@ namespace IGC
         bool isUniformAlloca = WI->isUniform(&I);
         if (isUniformAlloca)
         {
+            // add the meta-date to the alloca for promotion
             IRBuilder<> builder(&I);
             MDNode* node = MDNode::get(I.getContext(), ConstantAsMetadata::get(builder.getInt1(true)));
             I.setMetadata("uniform", node);
@@ -98,7 +99,25 @@ namespace IGC
             if (pIntr->getIntrinsicID() == GenISAIntrinsic::GenISA_assume_uniform)
             {
                 AssumeToErase.push_back(pIntr);
+                // add the meta-date to the alloca for promotion
+                auto OpV = pIntr->getOperand(0);
+                while (OpV)
+                {
+                   if (auto CI = dyn_cast<CastInst>(OpV))
+                   {
+                       OpV = CI->getOperand(0);
+                       continue;
+                   }
+                   if (auto ALI = dyn_cast<AllocaInst>(OpV))
+                   {
+                       IRBuilder<> builder(ALI);
+                       MDNode* node = MDNode::get(ALI->getContext(),
+                               ConstantAsMetadata::get(builder.getInt1(true)));
+                       ALI->setMetadata("UseAssumeUniform", node);
+                   }
+                   break;
+                }
             }
         }
     }
-}
+}

IGC/Compiler/CISACodeGen/LowerGEPForPrivMem.cpp

@@ -274,6 +274,7 @@ bool LowerGEPForPrivMem::CheckIfAllocaPromotable(llvm::AllocaInst* pAlloca)
         return false;
 
     bool isUniformAlloca = pAlloca->getMetadata("uniform") != nullptr;
+    bool useAssumeUniform = pAlloca->getMetadata("UseAssumeUniform") != nullptr;
     unsigned int allocaSize = extractConstAllocaSize(pAlloca);
     unsigned int allowedAllocaSizeInBytes = MAX_ALLOCA_PROMOTE_GRF_NUM * 4;
 
@@ -315,7 +316,7 @@ bool LowerGEPForPrivMem::CheckIfAllocaPromotable(llvm::AllocaInst* pAlloca)
         allocaSize = iSTD::Round(allocaSize, SIMD_PRESSURE_MULTIPLIER) / SIMD_PRESSURE_MULTIPLIER;
     }
 
-    if (allocaSize <= IGC_GET_FLAG_VALUE(ByPassAllocaSizeHeuristic))
+    if (useAssumeUniform || allocaSize <= IGC_GET_FLAG_VALUE(ByPassAllocaSizeHeuristic))
     {
         return true;
     }