From: Duncan Sands <baldrick@free.fr>
Date: Wed, 12 Nov 2008 08:37:57 +0000 (+0000)
Subject: Simplify SplitVecRes_EXTRACT_SUBVECTOR.  This means
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1e465a35c8cd3d2ddd5e1d15fca7ffd3a8dbb565;p=oota-llvm.git

Simplify SplitVecRes_EXTRACT_SUBVECTOR.  This means
that it no longer handles non-power-of-two vectors.
However it previously only handled them sometimes,
depending on obscure numerical relationships between
the index and vector type.  For example, for a vector
of length 6, it would succeed if and only if the
index was an even multiple of 6.  I consider this
more confusing than useful.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59122 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index bbc7c6ab3ea..106a811ff9f 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -355,8 +355,8 @@ void DAGTypeLegalizer::SplitVectorResult(SDNode *N, unsigned ResNo) {
   case ISD::FPOWI:             SplitVecRes_FPOWI(N, Lo, Hi); break;
   case ISD::INSERT_VECTOR_ELT: SplitVecRes_INSERT_VECTOR_ELT(N, Lo, Hi); break;
   case ISD::LOAD:           SplitVecRes_LOAD(cast<LoadSDNode>(N), Lo, Hi);break;
-  case ISD::VECTOR_SHUFFLE: SplitVecRes_VECTOR_SHUFFLE(N, Lo, Hi); break;
-  case ISD::VSETCC:         SplitVecRes_VSETCC(N, Lo, Hi); break;
+  case ISD::VECTOR_SHUFFLE:    SplitVecRes_VECTOR_SHUFFLE(N, Lo, Hi); break;
+  case ISD::VSETCC:            SplitVecRes_VSETCC(N, Lo, Hi); break;
 
   case ISD::CTTZ:
   case ISD::CTLZ:
@@ -520,28 +520,20 @@ void DAGTypeLegalizer::SplitVecRes_CONVERT_RNDSAT(SDNode *N, SDValue &Lo,
 
 void DAGTypeLegalizer::SplitVecRes_EXTRACT_SUBVECTOR(SDNode *N, SDValue &Lo,
                                                      SDValue &Hi) {
+  SDValue Vec = N->getOperand(0);
+  SDValue Idx = N->getOperand(1);
+  MVT IdxVT = Idx.getValueType();
+
   MVT LoVT, HiVT;
   GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
-  unsigned LoNumElts = LoVT.getVectorNumElements();
+  // The indices are not guaranteed to be a multiple of the new vector
+  // size unless the original vector type was split in two.
+  assert(LoVT == HiVT && "Non power-of-two vectors not supported!");
 
-  SDValue Vec = N->getOperand(0);
-  SDValue Idx = N->getOperand(1);
-  MVT     IdxVT = Idx.getValueType();
   Lo = DAG.getNode(ISD::EXTRACT_SUBVECTOR, LoVT, Vec, Idx);
-
-  ConstantSDNode *CIdx = dyn_cast<ConstantSDNode>(Idx);
-  if (CIdx) {
-    unsigned IdxVal = CIdx->getZExtValue();
-    assert (IdxVal % LoVT.getVectorNumElements() == 0 &&
-           (IdxVal+LoNumElts) % HiVT.getVectorNumElements()==0 &&
-            "Index must be a multiple of the result type");
-    Hi = DAG.getNode(ISD::EXTRACT_SUBVECTOR, HiVT, Vec,
-                     DAG.getConstant(IdxVal + LoNumElts, IdxVT));
-  } else {
-    assert(LoVT == HiVT && "Low and High value type should be the same");
-    Idx = DAG.getNode(ISD::ADD, IdxVT, Idx, DAG.getConstant(LoNumElts, IdxVT));
-    Hi = DAG.getNode(ISD::EXTRACT_SUBVECTOR, HiVT, Vec, Idx);
-  }
+  Idx = DAG.getNode(ISD::ADD, IdxVT, Idx,
+                    DAG.getConstant(LoVT.getVectorNumElements(), IdxVT));
+  Hi = DAG.getNode(ISD::EXTRACT_SUBVECTOR, HiVT, Vec, Idx);
 }
 
 void DAGTypeLegalizer::SplitVecRes_FPOWI(SDNode *N, SDValue &Lo,