Added a x86 dag combine to increase the chances to use a
movq for v2i64 on x86-32.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68368 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index b9c17f2..c5a6acb 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -8061,15 +8061,43 @@
/// PerformShuffleCombine - Combine a vector_shuffle that is equal to
/// build_vector load1, load2, load3, load4, <0, 1, 2, 3> into a 128-bit load
/// if the load addresses are consecutive, non-overlapping, and in the right
-/// order.
+/// order. In the case of v2i64, it will see if it can rewrite the
+/// shuffle to be an appropriate build vector so it can take advantage of
+// performBuildVectorCombine.
static SDValue PerformShuffleCombine(SDNode *N, SelectionDAG &DAG,
const TargetLowering &TLI) {
- MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
DebugLoc dl = N->getDebugLoc();
MVT VT = N->getValueType(0);
MVT EVT = VT.getVectorElementType();
SDValue PermMask = N->getOperand(2);
unsigned NumElems = PermMask.getNumOperands();
+
+ // For x86-32 machines, if we see an insert and then a shuffle in a v2i64
+ // where the upper half is 0, it is advantageous to rewrite it as a build
+ // vector of (0, val) so it can use movq.
+ if (VT == MVT::v2i64) {
+ SDValue In[2];
+ In[0] = N->getOperand(0);
+ In[1] = N->getOperand(1);
+ unsigned Idx0 =cast<ConstantSDNode>(PermMask.getOperand(0))->getZExtValue();
+ unsigned Idx1 =cast<ConstantSDNode>(PermMask.getOperand(1))->getZExtValue();
+ if (In[0].getValueType().getVectorNumElements() == NumElems &&
+ In[Idx0/2].getOpcode() == ISD::INSERT_VECTOR_ELT &&
+ In[Idx1/2].getOpcode() == ISD::BUILD_VECTOR) {
+ ConstantSDNode* InsertVecIdx =
+ dyn_cast<ConstantSDNode>(In[Idx0/2].getOperand(2));
+ if (InsertVecIdx &&
+ InsertVecIdx->getZExtValue() == (Idx0 % 2) &&
+ isZeroNode(In[Idx1/2].getOperand(Idx1 % 2))) {
+ return DAG.getNode(ISD::BUILD_VECTOR, dl, VT,
+ In[Idx0/2].getOperand(1),
+ In[Idx1/2].getOperand(Idx1 % 2));
+ }
+ }
+ }
+
+ // Try to combine a vector_shuffle into a 128-bit load.
+ MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
SDNode *Base = NULL;
if (!EltsFromConsecutiveLoads(N, PermMask, NumElems, EVT, Base,
DAG, MFI, TLI))