Fix libcall code to not pass a NULL Chain to LowerCallTo

Fix libcall code to not crash or assert looking for an ADJCALLSTACKUP node
  when it is known that there is no ADJCALLSTACKDOWN to match.
Expand i64 multiply when ISD::MULHU is legal for the target.

llvm-svn: 21214

1 files changed, 30 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index d5d707b87a3..e1d9836f812 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -910,6 +910,8 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
   case ISD::ADD:
   case ISD::SUB:
   case ISD::MUL:
+  case ISD::MULHS:
+  case ISD::MULHU:
   case ISD::UDIV:
   case ISD::SDIV:
   case ISD::AND:
@@ -1678,12 +1680,20 @@ static SDNode *FindAdjCallStackUp(SDNode *Node) {
 static SDOperand FindInputOutputChains(SDNode *OpNode, SDNode *&OutChain,
                                        SDOperand Entry) {
   SDNode *LatestAdjCallStackDown = Entry.Val;
+  SDNode *LatestAdjCallStackUp = 0;
   FindLatestAdjCallStackDown(OpNode, LatestAdjCallStackDown);
   //std::cerr << "Found node: "; LatestAdjCallStackDown->dump(); std::cerr <<"\n";
-
-  SDNode *LatestAdjCallStackUp = FindAdjCallStackUp(LatestAdjCallStackDown);
-
-
+  
+  // It is possible that no ISD::ADJCALLSTACKDOWN was found because there is no
+  // previous call in the function.  LatestCallStackDown may in that case be
+  // the entry node itself.  Do not attempt to find a matching ADJCALLSTACKUP
+  // unless LatestCallStackDown is an ADJCALLSTACKDOWN.
+  if (LatestAdjCallStackDown->getOpcode() == ISD::ADJCALLSTACKDOWN)
+    LatestAdjCallStackUp = FindAdjCallStackUp(LatestAdjCallStackDown);
+  else
+    LatestAdjCallStackUp = Entry.Val;
+  assert(LatestAdjCallStackUp && "NULL return from FindAdjCallStackUp");
+  
   SDNode *EarliestAdjCallStackUp = 0;
   FindEarliestAdjCallStackUp(OpNode, EarliestAdjCallStackUp);
 
@@ -2042,7 +2052,22 @@ void SelectionDAGLegalize::ExpandOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi){
     ExpandByParts(ISD::SUB_PARTS, Node->getOperand(0), Node->getOperand(1),
                   Lo, Hi);
     break;
-  case ISD::MUL:  Lo = ExpandLibCall("__muldi3" , Node, Hi); break;
+  case ISD::MUL: {
+    if (TLI.getOperationAction(ISD::MULHU, NVT) == TargetLowering::Legal) {
+      SDOperand LL, LH, RL, RH;
+      ExpandOp(Node->getOperand(0), LL, LH);
+      ExpandOp(Node->getOperand(1), RL, RH);
+      Hi = DAG.getNode(ISD::MULHU, NVT, LL, RL);
+      RH = DAG.getNode(ISD::MUL, NVT, LL, RH);
+      LH = DAG.getNode(ISD::MUL, NVT, LH, RL);
+      Hi = DAG.getNode(ISD::ADD, NVT, Hi, RH);
+      Hi = DAG.getNode(ISD::ADD, NVT, Hi, LH);
+      Lo = DAG.getNode(ISD::MUL, NVT, LL, RL);
+    } else {
+      Lo = ExpandLibCall("__muldi3" , Node, Hi); break;
+    }
+    break;
+  }
   case ISD::SDIV: Lo = ExpandLibCall("__divdi3" , Node, Hi); break;
   case ISD::UDIV: Lo = ExpandLibCall("__udivdi3", Node, Hi); break;
   case ISD::SREM: Lo = ExpandLibCall("__moddi3" , Node, Hi); break;