_OS_SUMMARY

_OS_DESCRIPTION

Author: Ryan Taylor

IGC/Compiler/CustomUnsafeOptPass.cpp

@@ -2515,7 +2515,8 @@ class EarlyOutPatterns : public FunctionPass
         ArrayRef<Instruction*> Values,
         const DenseSet<const Value*>& FoldedVals);
     static unsigned int shortPathToOutput(Value* inst, unsigned int limit);
-
+    static Instruction* FindLastFoldedValue(const DenseSet<const Value*>& FoldedVals, 
+        BasicBlock* currentBB);
     CodeGenContext* m_ctx;
     unsigned int m_ShaderLength;
 };
@@ -3477,6 +3478,21 @@ DenseSet<const Value*> EarlyOutPatterns::tryAndFoldValues(ArrayRef<Instruction*>
     return FoldedVals;
 }
 
+Instruction* EarlyOutPatterns::FindLastFoldedValue(const DenseSet<const Value*>& FoldedVals, BasicBlock* currentBB)
+{
+    // traverse the block backwards and find the last folded value
+    for (BasicBlock::reverse_iterator re = currentBB->rbegin(), ri = currentBB->rend(); re != ri; ++re)
+    {
+        if (FoldedVals.count(&(*re)))
+        {
+            re--;
+            return &*re;
+        }
+    }
+    // default to return the last instruction in the block
+    return &*(currentBB->rbegin());
+}
+
 // return the new block where the code after inst was moved
 BasicBlock* EarlyOutPatterns::SplitBasicBlock(Instruction* inst, const DenseSet<const Value*>& FoldedVals)
 {
@@ -3491,7 +3507,7 @@ BasicBlock* EarlyOutPatterns::SplitBasicBlock(Instruction* inst, const DenseSet<
     elseBlock->getInstList().splice(elseBlock->begin(),
         currentBB->getInstList(),
         inst->getNextNode()->getIterator(),
-        currentBB->getTerminator()->getIterator());
+        FindLastFoldedValue(FoldedVals, currentBB)->getIterator());
     endifBlock->getInstList().splice(endifBlock->begin(), currentBB->getInstList(), currentBB->getTerminator());
     if (isa<ReturnInst>(endifBlock->getTerminator()))
     {
@@ -3502,7 +3518,6 @@ BasicBlock* EarlyOutPatterns::SplitBasicBlock(Instruction* inst, const DenseSet<
     // split the blocks
     ValueToValueMapTy VMap;
 
-    // TODO: Create if block only for affected instructions
     BasicBlock* ifBlock = CloneBasicBlock(elseBlock, VMap);
     ifBlock->setName(VALUE_NAME("EO_IF"));
     currentBB->getParent()->getBasicBlockList().insertAfter(currentBB->getIterator(), ifBlock);
@@ -3516,6 +3531,7 @@ BasicBlock* EarlyOutPatterns::SplitBasicBlock(Instruction* inst, const DenseSet<
                 II->setOperand(op, It->second);
         }
     }
+
     // create phi instruction
     for (auto II = elseBlock->begin(), IE = elseBlock->end(); II != IE; ++II)
     {
@@ -3535,6 +3551,7 @@ BasicBlock* EarlyOutPatterns::SplitBasicBlock(Instruction* inst, const DenseSet<
             }
         }
     }
+
     // replace the folded values with 0
     for (auto it : FoldedVals)
     {