public override Value VisitConditionalExpression([NotNull] ConditionalExpressionContext context)
{
EmitLocation(context);
var condition = context.Condition.Accept(this);
if (condition == null)
{
return(null);
}
var condBool = InstructionBuilder.Compare(RealPredicate.OrderedAndNotEqual, condition, Context.CreateConstant(0.0))
.RegisterName("ifcond");
var function = InstructionBuilder.InsertBlock.ContainingFunction;
var thenBlock = Context.CreateBasicBlock("then", function);
var elseBlock = Context.CreateBasicBlock("else");
var phiMergeBlock = Context.CreateBasicBlock("ifcont");
InstructionBuilder.Branch(condBool, thenBlock, elseBlock);
// generate then block
InstructionBuilder.PositionAtEnd(thenBlock);
var thenValue = context.ThenExpression.Accept(this);
if (thenValue == null)
{
return(null);
}
InstructionBuilder.Branch(phiMergeBlock);
// capture the insert in case generating thenExpression adds new blocks
thenBlock = InstructionBuilder.InsertBlock;
// generate else block
function.BasicBlocks.Add(elseBlock);
InstructionBuilder.PositionAtEnd(elseBlock);
var elseValue = context.ElseExpression.Accept(this);
if (elseValue == null)
{
return(null);
}
InstructionBuilder.Branch(phiMergeBlock);
elseBlock = InstructionBuilder.InsertBlock;
// generate PHI merge block
function.BasicBlocks.Add(phiMergeBlock);
InstructionBuilder.PositionAtEnd(phiMergeBlock);
var phiNode = InstructionBuilder.PhiNode(function.Context.DoubleType)
.RegisterName("iftmp");
phiNode.AddIncoming(thenValue, thenBlock);
phiNode.AddIncoming(elseValue, elseBlock);
return(phiNode);
}
public override Value Visit(ConditionalExpression conditionalExpression)
{
var condition = conditionalExpression.Condition.Accept(this);
if (condition == null)
{
return(null);
}
var condBool = InstructionBuilder.Compare(RealPredicate.OrderedAndNotEqual, condition, Context.CreateConstant(0.0))
.RegisterName("ifcond");
var function = InstructionBuilder.InsertBlock.ContainingFunction;
var thenBlock = function.AppendBasicBlock("then");
var elseBlock = function.AppendBasicBlock("else");
var continueBlock = function.AppendBasicBlock("ifcont");
InstructionBuilder.Branch(condBool, thenBlock, elseBlock);
// generate then block instructions
InstructionBuilder.PositionAtEnd(thenBlock);
var thenValue = conditionalExpression.ThenExpression.Accept(this);
if (thenValue == null)
{
return(null);
}
InstructionBuilder.Branch(continueBlock);
// capture the insert in case generating else adds new blocks
var thenResultBlock = InstructionBuilder.InsertBlock;
// generate else block
InstructionBuilder.PositionAtEnd(elseBlock);
var elseValue = conditionalExpression.ElseExpression.Accept(this);
if (elseValue == null)
{
return(null);
}
InstructionBuilder.Branch(continueBlock);
var elseResultBlock = InstructionBuilder.InsertBlock;
// generate continue block
InstructionBuilder.PositionAtEnd(continueBlock);
var phiNode = InstructionBuilder.PhiNode(function.Context.DoubleType)
.RegisterName("ifresult");
phiNode.AddIncoming((thenValue, thenResultBlock), (elseValue, elseResultBlock));
return(phiNode);
}
/*
* // Output for-loop as:
* // ...
* // start = startexpr
* // goto loop
* // loop:
* // variable = phi [start, loopheader], [nextvariable, loopend]
* // ...
* // bodyexpr
* // ...
* // loopend:
* // step = stepexpr
* // nextvariable = variable + step
* // endcond = endexpr
* // br endcond, loop, endloop
* // outloop:
*/
public override Value VisitForExpression([NotNull] ForExpressionContext context)
{
var function = InstructionBuilder.InsertBlock.ContainingFunction;
string varName = context.Initializer.Name;
var allocaVar = CreateEntryBlockAlloca(function, varName);
// Emit the start code first, without 'variable' in scope.
Value startVal = null;
if (context.Initializer.Value != null)
{
startVal = context.Initializer.Value.Accept(this);
if (startVal == null)
{
return(null);
}
}
else
{
startVal = Context.CreateConstant(0.0);
}
// store the value into allocated location
InstructionBuilder.Store(startVal, allocaVar);
// Make the new basic block for the loop header, inserting after current
// block.
var preHeaderBlock = InstructionBuilder.InsertBlock;
var loopBlock = Context.CreateBasicBlock("loop", function);
// Insert an explicit fall through from the current block to the loopBlock.
InstructionBuilder.Branch(loopBlock);
// Start insertion in loopBlock.
InstructionBuilder.PositionAtEnd(loopBlock);
// Start the PHI node with an entry for Start.
var variable = InstructionBuilder.PhiNode(Context.DoubleType)
.RegisterName(varName);
variable.AddIncoming(startVal, preHeaderBlock);
// Within the loop, the variable is defined equal to the PHI node. If it
// shadows an existing variable, we have to restore it, so save it now.
NamedValues.TryGetValue(varName, out Alloca oldValue);
NamedValues[varName] = allocaVar;
// Emit the body of the loop. This, like any other expr, can change the
// current BB. Note that we ignore the value computed by the body, but don't
// allow an error.
if (context.BodyExpression.Accept(this) == null)
{
return(null);
}
Value stepValue = Context.CreateConstant(1.0);
// DEBUG: How does ANTLR represent optional context (Null or IsEmpty == true)
if (context.StepExpression != null)
{
stepValue = context.StepExpression.Accept(this);
if (stepValue == null)
{
return(null);
}
}
// Compute the end condition.
Value endCondition = context.EndExpression.Accept(this);
if (endCondition == null)
{
return(null);
}
var curVar = InstructionBuilder.Load(allocaVar)
.RegisterName(varName);
var nextVar = InstructionBuilder.FAdd(curVar, stepValue)
.RegisterName("nextvar");
InstructionBuilder.Store(nextVar, allocaVar);
// Convert condition to a bool by comparing non-equal to 0.0.
endCondition = InstructionBuilder.Compare(RealPredicate.OrderedAndNotEqual, endCondition, Context.CreateConstant(1.0))
.RegisterName("loopcond");
// Create the "after loop" block and insert it.
var loopEndBlock = InstructionBuilder.InsertBlock;
var afterBlock = Context.CreateBasicBlock("afterloop", function);
// Insert the conditional branch into the end of LoopEndBB.
InstructionBuilder.Branch(endCondition, loopBlock, afterBlock);
InstructionBuilder.PositionAtEnd(afterBlock);
// Add a new entry to the PHI node for the backedge.
variable.AddIncoming(nextVar, loopEndBlock);
// Restore the unshadowed variable.
if (oldValue != null)
{
NamedValues[varName] = oldValue;
}
else
{
NamedValues.Remove(varName);
}
// for expr always returns 0.0 for consistency, there is no 'void'
return(Context.DoubleType.GetNullValue( ));
}
public override Value Visit(ForInExpression forInExpression)
{
var function = InstructionBuilder.InsertBlock.ContainingFunction;
string varName = forInExpression.LoopVariable.Name;
// Emit the start code first, without 'variable' in scope.
Value startVal;
if (forInExpression.LoopVariable.Initializer != null)
{
startVal = forInExpression.LoopVariable.Initializer.Accept(this);
if (startVal == null)
{
return(null);
}
}
else
{
startVal = Context.CreateConstant(0.0);
}
// Make the new basic block for the loop header, inserting after current
// block.
var preHeaderBlock = InstructionBuilder.InsertBlock;
var loopBlock = function.AppendBasicBlock("loop");
// Insert an explicit fall through from the current block to the loopBlock.
InstructionBuilder.Branch(loopBlock);
// Start insertion in loopBlock.
InstructionBuilder.PositionAtEnd(loopBlock);
// Start the PHI node with an entry for Start.
var variable = InstructionBuilder.PhiNode(Context.DoubleType)
.RegisterName(varName);
variable.AddIncoming(startVal, preHeaderBlock);
// Within the loop, the variable is defined equal to the PHI node.
// So, push a new scope for it and any values the body might set
using (NamedValues.EnterScope( ))
{
NamedValues[varName] = variable;
// Emit the body of the loop. This, like any other expression, can change the
// current BB. Note that we ignore the value computed by the body, but don't
// allow an error.
if (forInExpression.Body.Accept(this) == null)
{
return(null);
}
Value stepValue = forInExpression.Step.Accept(this);
if (stepValue == null)
{
return(null);
}
var nextVar = InstructionBuilder.FAdd(variable, stepValue)
.RegisterName("nextvar");
// Compute the end condition.
Value endCondition = forInExpression.Condition.Accept(this);
if (endCondition == null)
{
return(null);
}
// Convert condition to a bool by comparing non-equal to 0.0.
endCondition = InstructionBuilder.Compare(RealPredicate.OrderedAndNotEqual, endCondition, Context.CreateConstant(0.0))
.RegisterName("loopcond");
// capture loop end result block for loop variable PHI node
var loopEndBlock = InstructionBuilder.InsertBlock;
// Create the "after loop" block and insert it.
var afterBlock = function.AppendBasicBlock("afterloop");
// Insert the conditional branch into the end of LoopEndBB.
InstructionBuilder.Branch(endCondition, loopBlock, afterBlock);
InstructionBuilder.PositionAtEnd(afterBlock);
// Add a new entry to the PHI node for the back-edge.
variable.AddIncoming(nextVar, loopEndBlock);
// for expression always returns 0.0 for consistency, there is no 'void'
return(Context.DoubleType.GetNullValue( ));
}
}