Minor cleanups; add a better explanation for the issue with

BUILD_VECTOR.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72469 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 89d2cfc7d3793c3ae6bc3e9bc726fffffbc129a5..30dc8355c78e45bc38ca3d88e0e40365915ec10b 100644 (file)
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -111,10 +111,6 @@ public:
   void LegalizeDAG();
 
 private:
-  /// HandleOp - Legalize, Promote, or Expand the specified operand as
-  /// appropriate for its type.
-  void HandleOp(SDValue Op);
-
   /// LegalizeOp - We know that the specified value has a legal type.
   /// Recursively ensure that the operands have legal types, then return the
   /// result.
@@ -129,9 +125,6 @@ private:
   SDValue ExpandINSERT_VECTOR_ELT(SDValue Vec, SDValue Val,
                                   SDValue Idx, DebugLoc dl);
 
-  /// Useful 16 element vector type that is used to pass operands for widening.
-  typedef SmallVector<SDValue, 16> SDValueVector;
-
   /// ShuffleWithNarrowerEltType - Return a vector shuffle operation which
   /// performs the same shuffe in terms of order or result bytes, but on a type
   /// whose vector element type is narrower than the original shuffle type.
@@ -239,7 +232,7 @@ void SelectionDAGLegalize::LegalizeDAG() {
   DAG.AssignTopologicalOrder();
   for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
        E = prior(DAG.allnodes_end()); I != next(E); ++I)
-    HandleOp(SDValue(I, 0));
+    LegalizeOp(SDValue(I, 0));
 
   // Finally, it's possible the root changed.  Get the new root.
   SDValue OldRoot = DAG.getRoot();
@@ -336,22 +329,10 @@ bool SelectionDAGLegalize::LegalizeAllNodesNotLeadingTo(SDNode *N, SDNode *Dest,
   }
 
   // Okay, this node looks safe, legalize it and return false.
-  HandleOp(SDValue(N, 0));
+  LegalizeOp(SDValue(N, 0));
   return false;
 }
 
-/// HandleOp - Legalize, Promote, Widen, or Expand the specified operand as
-/// appropriate for its type.
-void SelectionDAGLegalize::HandleOp(SDValue Op) {
-  // Don't touch TargetConstants
-  if (Op.getOpcode() == ISD::TargetConstant)
-    return;
-  MVT VT = Op.getValueType();
-  // We should never see any illegal result types here.
-  assert(isTypeLegal(VT) && "Illegal type introduced after type legalization?");
-  (void)LegalizeOp(Op);
-}
-
 /// ExpandConstantFP - Expands the ConstantFP node to an integer constant or
 /// a load from the constant pool.
 static SDValue ExpandConstantFP(ConstantFPSDNode *CFP, bool UseCP,
@@ -800,8 +781,14 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
       Action = TargetLowering::Custom;
     break;
   case ISD::BUILD_VECTOR:
-    // A weird case: when a BUILD_VECTOR is custom-lowered, it doesn't legalize
-    // its operands first!
+    // A weird case: legalization for BUILD_VECTOR never legalizes the
+    // operands!
+    // FIXME: This really sucks... changing it isn't semantically incorrect,
+    // but it massively pessimizes the code for floating-point BUILD_VECTORs
+    // because ConstantFP operands get legalized into constant pool loads
+    // before the BUILD_VECTOR code can see them.  It doesn't usually bite,
+    // though, because BUILD_VECTORS usually get lowered into other nodes
+    // which get legalized properly.
     SimpleFinishLegalizing = false;
     break;
   default: