Instead of a vector load, shuffle and then extract an element. Load the element from address with an offset.
pshufd $1, (%rdi), %xmm0
movd %xmm0, %eax
=>
movl 4(%rdi), %eax
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51026 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f05f444..058e60f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1838,6 +1838,28 @@
}
+/// getShuffleScalarElt - Returns the scalar element that will make up the ith
+/// element of the result of the vector shuffle.
+SDOperand SelectionDAG::getShuffleScalarElt(const SDNode *N, unsigned Idx) {
+ MVT::ValueType VT = N->getValueType(0);
+ SDOperand PermMask = N->getOperand(2);
+ unsigned NumElems = PermMask.getNumOperands();
+ SDOperand V = (Idx < NumElems) ? N->getOperand(0) : N->getOperand(1);
+ Idx %= NumElems;
+ if (V.getOpcode() == ISD::SCALAR_TO_VECTOR) {
+ return (Idx == 0)
+ ? V.getOperand(0) : getNode(ISD::UNDEF, MVT::getVectorElementType(VT));
+ }
+ if (V.getOpcode() == ISD::VECTOR_SHUFFLE) {
+ SDOperand Elt = PermMask.getOperand(Idx);
+ if (Elt.getOpcode() == ISD::UNDEF)
+ return getNode(ISD::UNDEF, MVT::getVectorElementType(VT));
+ return getShuffleScalarElt(V.Val,cast<ConstantSDNode>(Elt)->getValue());
+ }
+ return SDOperand();
+}
+
+
/// getNode - Gets or creates the specified node.
///
SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT) {