[AVX] Support EXTRACT_SUBVECTOR on x86. This provides a default

implementation of EXTRACT_SUBVECTOR for x86, going through the stack
in a similr fashion to how the codegen implements BUILD_VECTOR.
Eventually this will get matched to VEXTRACTF128 if AVX is available.

llvm-svn: 124292

2 files changed, 24 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 67a84a8ea66..2b5e1f11901 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -625,9 +625,9 @@ void DAGTypeLegalizer::SplitVecRes_CONVERT_RNDSAT(SDNode *N, SDValue &Lo,
     EVT InNVT = EVT::getVectorVT(*DAG.getContext(), InVT.getVectorElementType(),
                                  LoVT.getVectorNumElements());
     VLo = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, InNVT, InOp,
-                     DAG.getIntPtrConstant(0));
+                      DAG.getIntPtrConstant(0));
     VHi = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, InNVT, InOp,
-                     DAG.getIntPtrConstant(InNVT.getVectorNumElements()));
+                      DAG.getIntPtrConstant(InNVT.getVectorNumElements()));
     break;
   }
   }
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index e751e22a81b..68d7621f6b4 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2864,11 +2864,30 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, EVT VT,
       return getConstant(ShiftedVal.trunc(ElementSize), VT);
     }
     break;
-  case ISD::EXTRACT_SUBVECTOR:
-    if (N1.getValueType() == VT) // Trivial extraction.
-      return N1;
+  case ISD::EXTRACT_SUBVECTOR: {
+    SDValue Index = N2;
+    if (VT.isSimple() && N1.getValueType().isSimple()) {
+      assert(VT.isVector() && N1.getValueType().isVector() &&
+             "Extract subvector VTs must be a vectors!");
+      assert(VT.getVectorElementType() == N1.getValueType().getVectorElementType() &&
+             "Extract subvector VTs must have the same element type!");
+      assert(VT.getSimpleVT() <= N1.getValueType().getSimpleVT() &&
+             "Extract subvector must be from larger vector to smaller vector!");
+
+      if (ConstantSDNode *CSD = dyn_cast<ConstantSDNode>(Index.getNode())) {
+        uint64_t Idx = CSD->getZExtValue();
+        assert((VT.getVectorNumElements() + Idx
+                <= N1.getValueType().getVectorNumElements())
+               && "Extract subvector overflow!");
+      }
+
+      // Trivial extraction.
+      if (VT.getSimpleVT() == N1.getValueType().getSimpleVT())
+        return N1;
+    }
     break;
   }
+  }
 
   if (N1C) {
     if (N2C) {