[llvm] r249236 - [DAGCombiner] Merge SIGN_EXTEND_INREG vector constant folding methods. NCI.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sat Oct  3 11:26:52 2015
New Revision: 249236

URL: http://llvm.org/viewvc/llvm-project?rev=249236&view=rev
Log:
[DAGCombiner] Merge SIGN_EXTEND_INREG vector constant folding methods. NCI.

visitSIGN_EXTEND_INREG calls SelectionDAG::getNode to constant fold scalar constants but handles vector constants itself, despite getNode being capable of dealing with them.

This required a minor change to the getNode implementation to actually deal with cases where the scalars of a BUILD_VECTOR were wider integers than the vector type - which was the only extra ability of the visitSIGN_EXTEND_INREG implementation.

No codegen intended and all existing tests remain the same.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=249236&r1=249235&r2=249236&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sat Oct  3 11:26:52 2015
@@ -6791,8 +6791,11 @@ SDValue DAGCombiner::visitSIGN_EXTEND_IN
   unsigned VTBits = VT.getScalarType().getSizeInBits();
   unsigned EVTBits = EVT.getScalarType().getSizeInBits();
 
+  if (N0.isUndef())
+    return DAG.getUNDEF(VT);
+
   // fold (sext_in_reg c1) -> c1
-  if (isa<ConstantSDNode>(N0) || N0.getOpcode() == ISD::UNDEF)
+  if (isConstantIntBuildVectorOrConstantInt(N0))
     return DAG.getNode(ISD::SIGN_EXTEND_INREG, SDLoc(N), VT, N0, N1);
 
   // If the input is already sign extended, just drop the extension.
@@ -6885,29 +6888,6 @@ SDValue DAGCombiner::visitSIGN_EXTEND_IN
                          BSwap, N1);
   }
 
-  // Fold a sext_inreg of a build_vector of ConstantSDNodes or undefs
-  // into a build_vector.
-  if (ISD::isBuildVectorOfConstantSDNodes(N0.getNode())) {
-    SmallVector<SDValue, 8> Elts;
-    unsigned NumElts = N0->getNumOperands();
-    unsigned ShAmt = VTBits - EVTBits;
-
-    for (unsigned i = 0; i != NumElts; ++i) {
-      SDValue Op = N0->getOperand(i);
-      if (Op->getOpcode() == ISD::UNDEF) {
-        Elts.push_back(Op);
-        continue;
-      }
-
-      ConstantSDNode *CurrentND = cast<ConstantSDNode>(Op);
-      const APInt &C = APInt(VTBits, CurrentND->getAPIntValue().getZExtValue());
-      Elts.push_back(DAG.getConstant(C.shl(ShAmt).ashr(ShAmt).getZExtValue(),
-                                     SDLoc(Op), Op.getValueType()));
-    }
-
-    return DAG.getNode(ISD::BUILD_VECTOR, SDLoc(N), VT, Elts);
-  }
-
   return SDValue();
 }
 

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=249236&r1=249235&r2=249236&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Sat Oct  3 11:26:52 2015
@@ -3576,13 +3576,13 @@ SDValue SelectionDAG::getNode(unsigned O
       SmallVector<SDValue, 8> Ops;
       for (int i = 0, e = VT.getVectorNumElements(); i != e; ++i) {
         SDValue Op = N1.getOperand(i);
-        if (Op.getValueType() != VT.getScalarType()) break;
         if (Op.getOpcode() == ISD::UNDEF) {
-          Ops.push_back(Op);
+          Ops.push_back(getUNDEF(VT.getScalarType()));
           continue;
         }
         if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
           APInt Val = C->getAPIntValue();
+          Val = Val.zextOrTrunc(VT.getScalarSizeInBits());
           Ops.push_back(SignExtendInReg(Val));
           continue;
         }