|
public AddPhiIncoming ( |
||
| phiNode | ||
| value | ||
| block | ||
| Результат | void | |
public override Value CodeGen(IRBuilder builder)
{
Value startV = this.Start.CodeGen(builder);
if(startV.IsNull) return startV;
BasicBlock startBlock = builder.GetInsertPoint();
Function func = startBlock.GetParent();
BasicBlock loopBB = func.AppendBasicBlock("loop");
builder.BuildBr(loopBB);
builder.SetInsertPoint(loopBB);
Value variable = builder.BuildPhi(TypeRef.CreateDouble(), this.VarName, new PhiIncoming(startV, startBlock));
/* 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. */
Value oldVal = Value.Null;
CodeGenManager.NamedValues.TryGetValue(this.VarName, out oldVal);
CodeGenManager.NamedValues[this.VarName] = variable;
/* 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 */
Body.CodeGen(builder);
// Emit the step value;
Value stepV = Value.Null;
if(this.Step != null)
stepV = this.Step.CodeGen(builder);
else
stepV = Value.CreateConstDouble(1);
Value nextVar = builder.BuildFAdd(variable, stepV, "nextvar");
// Compute the end condition
Value endCond = this.End.CodeGen(builder);
endCond = builder.BuildFCmp(endCond, LLVMRealPredicate.RealONE, Value.CreateConstDouble(0), "loopcond");
BasicBlock loopEndBB = builder.GetInsertPoint();
BasicBlock afterBB = func.AppendBasicBlock("afterloop");
builder.BuildCondBr(endCond, loopBB, afterBB);
builder.SetInsertPoint(afterBB);
builder.AddPhiIncoming(variable, nextVar, loopEndBB);
if(!oldVal.IsNull)
CodeGenManager.NamedValues[this.VarName] = oldVal;
return Value.CreateConstDouble(0);
}