private MidExp SimplifyExpImpl(MidAttributeFetch exp, SimplifyEnv env)
{
return(_exps.AttributeFetch(
exp.Range,
exp.Obj,
exp.Attribute));
}
private MidExp SimplifyLabelExpImpl(
MidLabelExp labelExp,
MidLetExp letExp,
SimplifyEnv env)
{
// As long as the label doesn't occur in the
// bound expression, we can move it outside
// of the label's bounds.
if (!UsesLabel(letExp.Exp, labelExp.Label))
{
MidExp result = new MidLetExp(
letExp.Range,
letExp.Var,
letExp.Exp,
new MidLabelExp(
labelExp.Range,
labelExp.Label,
letExp.Body,
labelExp.Type));
result = SimplifyExp(result, env);
return(result);
}
return(labelExp);
}
private MidExp SimplifyExpImpl(MidAttributeRef val, SimplifyEnv env)
{
if (val.IsLazy)
{
return(_exps.AttributeRef(val.Range, val.Decl));
}
return(val);
}
private MidExp SimplifyExpImpl(MidLetExp exp, SimplifyEnv env)
{
if (exp.Exp is MidVal)
{
// The variable is just being bound to a simple
// value, so substitute it away:
var innerEnv = new SimplifyEnv(env);
innerEnv.Insert(exp.Var, (MidVal)exp.Exp);
return(SimplifyExp(exp.Body, innerEnv));
}
if (exp.Exp is MidBreakExp)
{
// Well, we can't possibly get to the rest of the
// expression, right?
return(exp.Exp);
}
if (exp.Body is MidVarRef)
{
var midVarRef = (MidVarRef)exp.Body;
if (midVarRef.Var == exp.Var)
{
return(exp.Exp);
}
}
if (exp.Exp is MidPath)
{
var midPath = (MidPath)exp.Exp;
// Try to substitute this path into
// any down-stream field references...
var midLet = exp;
while (midLet != null)
{
midLet.Exp = TryFoldPath(exp.Var, midLet.Exp, midPath);
midLet.Body = TryFoldPath(exp.Var, midLet.Body, midPath);
midLet = midLet.Body as MidLetExp;
}
}
if (!UsesVar(exp.Body, exp.Var) && !MightHaveSideEffects(exp.Exp))
{
// \todo: Should be able to DCE the let expression away,
// but to do that we need to be sure it doesn't have
// any side-effects... :(
return(exp.Body);
}
return(exp);
}
private MidExp SimplifyLabelExpImpl(
MidLabelExp labelExp,
MidExp exp,
SimplifyEnv env)
{
if (!UsesLabel(exp, labelExp.Label))
{
return(exp);
}
return(labelExp);
}
private MidExp SimplifyLabelExpImpl(
MidLabelExp labelExp,
MidBreakExp breakExp,
SimplifyEnv env)
{
if (labelExp.Label == breakExp.Label)
{
return(breakExp.Value);
}
return(labelExp);
}
private MidExp SimplifyExp(MidExp exp, SimplifyEnv env)
{
if (exp == null)
{
return(null);
}
var transform = new MidTransform(
null, // no pre-transform
(e) => SimplifyExpImpl((dynamic)e, env));
return(transform.Transform(exp));
}
public SimplifyEnv(
SimplifyEnv parent)
{
_parent = parent;
}
private MidExp SimplifyExpImpl(MidAttributeRef val, SimplifyEnv env)
{
if (val.IsLazy)
{
return _exps.AttributeRef(val.Range, val.Decl);
}
return val;
}
private MidExp SimplifyExpImpl(MidLabelExp exp, SimplifyEnv env)
{
return(SimplifyLabelExpImpl(exp, (dynamic)exp.Body, env));
}
private MidExp SimplifyExpImpl(MidVarRef val, SimplifyEnv env)
{
return(env.Lookup(val));
}
private MidExp SimplifyExpImpl(MidAttributeFetch exp, SimplifyEnv env)
{
return _exps.AttributeFetch(
exp.Range,
exp.Obj,
exp.Attribute);
}
private MidExp SimplifyExpImpl(MidVarRef val, SimplifyEnv env)
{
return env.Lookup(val);
}
private MidExp SimplifyExpImpl(MidExp exp, SimplifyEnv env)
{
return(exp);
}
private MidExp SimplifyExpImpl(MidExp exp, SimplifyEnv env)
{
return exp;
}
private MidExp SimplifyLabelExpImpl(
MidLabelExp labelExp,
MidExp exp,
SimplifyEnv env)
{
if (!UsesLabel(exp, labelExp.Label))
return exp;
return labelExp;
}
private MidExp SimplifyLabelExpImpl(
MidLabelExp labelExp,
MidBreakExp breakExp,
SimplifyEnv env)
{
if (labelExp.Label == breakExp.Label)
{
return breakExp.Value;
}
return labelExp;
}
private MidExp SimplifyLabelExpImpl(
MidLabelExp labelExp,
MidLetExp letExp,
SimplifyEnv env)
{
// As long as the label doesn't occur in the
// bound expression, we can move it outside
// of the label's bounds.
if (!UsesLabel(letExp.Exp, labelExp.Label))
{
MidExp result = new MidLetExp(
letExp.Range,
letExp.Var,
letExp.Exp,
new MidLabelExp(
labelExp.Range,
labelExp.Label,
letExp.Body,
labelExp.Type));
result = SimplifyExp(result, env);
return result;
}
return labelExp;
}
private MidExp SimplifyExpImpl(MidLetExp exp, SimplifyEnv env)
{
if (exp.Exp is MidVal)
{
// The variable is just being bound to a simple
// value, so substitute it away:
var innerEnv = new SimplifyEnv(env);
innerEnv.Insert(exp.Var, (MidVal) exp.Exp);
return SimplifyExp(exp.Body, innerEnv);
}
if (exp.Exp is MidBreakExp)
{
// Well, we can't possibly get to the rest of the
// expression, right?
return exp.Exp;
}
if (exp.Body is MidVarRef)
{
var midVarRef = (MidVarRef)exp.Body;
if (midVarRef.Var == exp.Var)
return exp.Exp;
}
if (exp.Exp is MidPath)
{
var midPath = (MidPath)exp.Exp;
// Try to substitute this path into
// any down-stream field references...
var midLet = exp;
while (midLet != null)
{
midLet.Exp = TryFoldPath(exp.Var, midLet.Exp, midPath);
midLet.Body = TryFoldPath(exp.Var, midLet.Body, midPath);
midLet = midLet.Body as MidLetExp;
}
}
if (!UsesVar(exp.Body, exp.Var) && !MightHaveSideEffects(exp.Exp))
{
// \todo: Should be able to DCE the let expression away,
// but to do that we need to be sure it doesn't have
// any side-effects... :(
return exp.Body;
}
return exp;
}
private MidExp SimplifyExpImpl(MidLabelExp exp, SimplifyEnv env)
{
return SimplifyLabelExpImpl(exp, (dynamic) exp.Body, env);
}
public SimplifyEnv(
SimplifyEnv parent)
{
_parent = parent;
}
private MidExp SimplifyExp(MidExp exp, SimplifyEnv env)
{
if (exp == null)
return null;
var transform = new MidTransform(
null, // no pre-transform
(e) => SimplifyExpImpl((dynamic)e, env));
return transform.Transform(exp);
}
