|
public BuildPhi ( |
||
| type | ||
| name | string | |
| incoming | ||
| return | ||
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);
}
public override Value CodeGen(IRBuilder builder)
{
Value condV = this.Cond.CodeGen(builder);
if(condV.IsNull) return condV;
condV = builder.BuildFCmp(condV, LLVMRealPredicate.RealONE,
Value.CreateConstDouble(0));
BasicBlock startBlock = builder.GetInsertPoint();
Function func = startBlock.GetParent();
BasicBlock thenBB = func.AppendBasicBlock("then");
builder.SetInsertPoint(thenBB);
Value thenV = this.Then.CodeGen(builder);
if(thenV.IsNull) return thenV;
/* Codegen of 'then' can change the current block, update then_bb for the
* phi. We create a new name because one is used for the phi node, and the
* other is used for the conditional branch. */
BasicBlock newThenBB = builder.GetInsertPoint();
// Emit else block
BasicBlock elseBB = func.AppendBasicBlock("else");
func.AppendBasicBlock(elseBB);
builder.SetInsertPoint(elseBB);
Value elseV = this.Else.CodeGen(builder);
if(elseV.IsNull) return elseV;
// Codegen of 'Else' can change the current block, update ElseBB for the PHI.
BasicBlock newElseBB = builder.GetInsertPoint();
// Emit merge block
BasicBlock mergeBB = func.AppendBasicBlock("ifcont");
func.AppendBasicBlock(mergeBB);
builder.SetInsertPoint(mergeBB);
PhiIncoming incoming = new PhiIncoming();
incoming.Add(thenV, thenBB);
incoming.Add(elseV, elseBB);
Value phi = builder.BuildPhi(TypeRef.CreateDouble(), "iftmp", incoming);
builder.SetInsertPoint(startBlock);
builder.BuildCondBr(condV, thenBB, elseBB);
builder.SetInsertPoint(thenBB);
builder.BuildBr(mergeBB);
builder.SetInsertPoint(elseBB);
builder.BuildBr(mergeBB);
builder.SetInsertPoint(mergeBB);
return phi;
}
