While converting one of the operands to a memory operand, we need to check if it is Legal and does not result into a cyclic dep.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91904 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PIC16/PIC16ISelLowering.cpp b/lib/Target/PIC16/PIC16ISelLowering.cpp
index 4d2096e..3cd6f9f 100644
--- a/lib/Target/PIC16/PIC16ISelLowering.cpp
+++ b/lib/Target/PIC16/PIC16ISelLowering.cpp
@@ -1482,7 +1482,8 @@
// operand no. of the operand to be converted in 'MemOp'. Remember, PIC16 has
// no instruction that can operation on two registers. Most insns take
// one register and one memory operand (addwf) / Constant (addlw).
-bool PIC16TargetLowering::NeedToConvertToMemOp(SDValue Op, unsigned &MemOp) {
+bool PIC16TargetLowering::NeedToConvertToMemOp(SDValue Op, unsigned &MemOp,
+ SelectionDAG &DAG) {
// If one of the operand is a constant, return false.
if (Op.getOperand(0).getOpcode() == ISD::Constant ||
Op.getOperand(1).getOpcode() == ISD::Constant)
@@ -1491,11 +1492,33 @@
// Return false if one of the operands is already a direct
// load and that operand has only one use.
if (isDirectLoad(Op.getOperand(0))) {
- if (Op.getOperand(0).hasOneUse())
- return false;
- else
- MemOp = 0;
+ if (Op.getOperand(0).hasOneUse()) {
+ // Legal and profitable folding check uses the NodeId of DAG nodes.
+ // This NodeId is assigned by topological order. Therefore first
+ // assign topological order then perform legal and profitable check.
+ // Note:- Though this ordering is done before begining with legalization,
+ // newly added node during legalization process have NodeId=-1 (NewNode)
+ // therefore before performing any check proper ordering of the node is
+ // required.
+ DAG.AssignTopologicalOrder();
+
+ // Direct load operands are folded in binary operations. But before folding
+ // verify if this folding is legal. Fold only if it is legal otherwise
+ // convert this direct load to a separate memory operation.
+ if(ISel->IsLegalAndProfitableToFold(Op.getOperand(0).getNode(),
+ Op.getNode(), Op.getNode()))
+ return false;
+ else
+ MemOp = 0;
+ }
}
+
+ // For operations that are non-cummutative there is no need to check
+ // for right operand because folding right operand may result in
+ // incorrect operation.
+ if (! SelectionDAG::isCommutativeBinOp(Op.getOpcode()))
+ return true;
+
if (isDirectLoad(Op.getOperand(1))) {
if (Op.getOperand(1).hasOneUse())
return false;
@@ -1514,7 +1537,7 @@
assert (Op.getValueType() == MVT::i8 && "illegal Op to lower");
unsigned MemOp = 1;
- if (NeedToConvertToMemOp(Op, MemOp)) {
+ if (NeedToConvertToMemOp(Op, MemOp, DAG)) {
// Put one value on stack.
SDValue NewVal = ConvertToMemOperand (Op.getOperand(MemOp), DAG, dl);
@@ -1533,7 +1556,7 @@
assert (Op.getValueType() == MVT::i8 && "illegal add to lower");
DebugLoc dl = Op.getDebugLoc();
unsigned MemOp = 1;
- if (NeedToConvertToMemOp(Op, MemOp)) {
+ if (NeedToConvertToMemOp(Op, MemOp, DAG)) {
// Put one value on stack.
SDValue NewVal = ConvertToMemOperand (Op.getOperand(MemOp), DAG, dl);
@@ -1564,7 +1587,8 @@
// Nothing to do if the first operand is already a direct load and it has
// only one use.
- if (isDirectLoad(Op.getOperand(0)) && Op.getOperand(0).hasOneUse())
+ unsigned MemOp = 0;
+ if (! NeedToConvertToMemOp(Op, MemOp, DAG))
return Op;
// Put first operand on stack.