From 56107e21a5cb5f2114dd1974c86f17cda47005e5 Mon Sep 17 00:00:00 2001
From: Robert Bocchino <bocchino@illinois.edu>
Date: Tue, 10 Jan 2006 19:05:05 +0000
Subject: [PATCH] Added lower packed support for the extractelement operation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25180 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LowerPacked.cpp | 31 +++++++++++++++++++++++++++
 lib/Transforms/Scalar/SCCP.cpp        | 12 +++++++++++
 2 files changed, 43 insertions(+)

diff --git a/lib/Transforms/Scalar/LowerPacked.cpp b/lib/Transforms/Scalar/LowerPacked.cpp
index 45ed8b43fdd..e8338bb96f7 100644
--- a/lib/Transforms/Scalar/LowerPacked.cpp
+++ b/lib/Transforms/Scalar/LowerPacked.cpp
@@ -59,6 +59,10 @@ public:
    /// @param SELI the select operator to convert
    void visitSelectInst(SelectInst& SELI);
 
+   /// @brief Lowers packed extractelement instructions.
+   /// @param EI the extractelement operator to convert
+   void visitExtractElementInst(ExtractElementInst& EI);
+
    /// This function asserts if the instruction is a PackedType but
    /// is handled by another function.
    ///
@@ -332,6 +336,33 @@ void LowerPacked::visitSelectInst(SelectInst& SELI)
    }
 }
 
+void LowerPacked::visitExtractElementInst(ExtractElementInst& EI)
+{
+  std::vector<Value*>& op0Vals = getValues(EI.getOperand(0));
+  const PackedType *PTy = cast<PackedType>(EI.getOperand(0)->getType());
+  Value *op1 = EI.getOperand(1);
+
+  if (ConstantUInt *C = dyn_cast<ConstantUInt>(op1)) {
+    EI.replaceAllUsesWith(op0Vals[C->getValue()]);
+  } else {
+    AllocaInst *alloca = new AllocaInst(PTy->getElementType(),
+					ConstantUInt::get(Type::UIntTy, PTy->getNumElements()),
+					EI.getName() + ".alloca", &(EI.getParent()->getParent()->getEntryBlock().front()));
+    for (unsigned i = 0; i < PTy->getNumElements(); ++i) {
+      GetElementPtrInst *GEP = new GetElementPtrInst(alloca, ConstantUInt::get(Type::UIntTy, i),
+						     "store.ge", &EI);
+      new StoreInst(op0Vals[i], GEP, &EI);
+    }
+    GetElementPtrInst *GEP = new GetElementPtrInst(alloca, op1,
+						   EI.getName() + ".ge", &EI);
+    LoadInst *load = new LoadInst(GEP, EI.getName() + ".load", &EI);
+    EI.replaceAllUsesWith(load);
+  }
+
+  Changed = true;
+  instrsToRemove.push_back(&EI);
+}
+
 bool LowerPacked::runOnFunction(Function& F)
 {
    // initialize
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index 491ca73fa3b..1a76eb5e5e8 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -322,6 +322,7 @@ private:
   void visitSelectInst(SelectInst &I);
   void visitBinaryOperator(Instruction &I);
   void visitShiftInst(ShiftInst &I) { visitBinaryOperator(I); }
+  void visitExtractElementInst(ExtractElementInst &I);
 
   // Instructions that cannot be folded away...
   void visitStoreInst     (Instruction &I);
@@ -728,6 +729,17 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) {
   }
 }
 
+void SCCPSolver::visitExtractElementInst(ExtractElementInst &I) {
+  LatticeVal &ValState = getValueState(I.getOperand(0));
+  LatticeVal &IdxState = getValueState(I.getOperand(1));
+
+  if (ValState.isOverdefined() || IdxState.isOverdefined())
+    markOverdefined(&I);
+  else if(ValState.isConstant() && IdxState.isConstant())
+    markConstant(&I, ConstantExpr::getExtractElement(ValState.getConstant(),
+                                                     IdxState.getConstant()));
+}
+
 // Handle getelementptr instructions... if all operands are constants then we
 // can turn this into a getelementptr ConstantExpr.
 //