File backport-llvm-r205625 of Package llvm

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r205625 | tnorthover | 2014-04-04 16:49:21 +0200 (Fri, 04 Apr 2014) | 17 lines

ARM64: handle v1i1 types arising from setcc properly.

There were several overlapping problems here, and this solution is
closely inspired by the one adopted in AArch64 in r201381.

Firstly, scalarisation of v1i1 setcc operations simply fails if the
input types are legal. This is fixed in LegalizeVectorTypes.cpp this
time, and allows AArch64 code to be simplified slightly.

Second, vselect with such a setcc feeding into it ends up in
ScalarizeVectorOperand, where it's not handled. I experimented with an
implementation, but found that whatever DAG came out was rather
horrific. I think Hao's DAG combine approach is a good one for
quality, though there are edge cases it won't catch (to be fixed
separately).

Should fix PR19335.
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Index: lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp.orig
+++ lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -330,12 +330,24 @@ SDValue DAGTypeLegalizer::ScalarizeVecRe
   assert(N->getValueType(0).isVector() &&
          N->getOperand(0).getValueType().isVector() &&
          "Operand types must be vectors");
-
-  SDValue LHS = GetScalarizedVector(N->getOperand(0));
-  SDValue RHS = GetScalarizedVector(N->getOperand(1));
+  SDValue LHS = N->getOperand(0);
+  SDValue RHS = N->getOperand(1);
+  EVT OpVT = LHS.getValueType();
   EVT NVT = N->getValueType(0).getVectorElementType();
   SDLoc DL(N);
 
+  // The result needs scalarizing, but it's not a given that the source does.
+  if (getTypeAction(OpVT) == TargetLowering::TypeScalarizeVector) {
+    LHS = GetScalarizedVector(LHS);
+    RHS = GetScalarizedVector(RHS);
+  } else {
+    EVT VT = OpVT.getVectorElementType();
+    LHS = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, VT, LHS,
+                      DAG.getConstant(0, TLI.getVectorIdxTy()));
+    RHS = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, VT, RHS,
+                      DAG.getConstant(0, TLI.getVectorIdxTy()));
+  }
+
   // Turn it into a scalar SETCC.
   SDValue Res = DAG.getNode(ISD::SETCC, DL, MVT::i1, LHS, RHS,
                             N->getOperand(2));