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//
// Analysis.ConstantEvaluator.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2012 Alexander Chebaturkin
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using Mono.CodeContracts.Static.AST;
using Mono.CodeContracts.Static.ControlFlow;
using Mono.CodeContracts.Static.DataStructures;
using Mono.CodeContracts.Static.Lattices;
using Mono.CodeContracts.Static.Providers;
using Mono.CodeContracts.Static.Proving;
namespace Mono.CodeContracts.Static.Analysis.Numerical {
static partial class AnalysisFacade {
static partial class Bind<TVar, TExpr>
where TExpr : IEquatable<TExpr>
where TVar : IEquatable<TVar> {
class ConstantEvaluator {
readonly IExpressionContextProvider<TExpr, TVar> context_provider;
readonly IMetaDataProvider meta_data_provider;
public ConstantEvaluator (IExpressionContextProvider<TExpr, TVar> contextProvider,
IMetaDataProvider metaDataProvider)
{
context_provider = contextProvider;
meta_data_provider = metaDataProvider;
}
public bool TryEvaluateToConstant (APC pc, TVar dest, BinaryOperator op,
BoxedExpression left, BoxedExpression right,
out long value)
{
var type =
context_provider.ValueContext.GetType (
context_provider.MethodContext.CFG.Post (pc), dest);
long l;
long r;
if (type.IsNormal () && TryEvaluateToConstant (pc, left, out l) &&
TryEvaluateToConstant (pc, right, out r))
return TryEvaluate (type.Value, op, l, r, out value);
return false.Without (out value);
}
bool TryEvaluate (TypeNode type, BinaryOperator op, long l, long r, out long value)
{
if (TryEvaluateIndependent (op, l, r, out value))
return true;
if (meta_data_provider.System_Int32.Equals (type))
return TryEvaluateInt32 (op, (int) l, (int) r, out value);
return false.Without (out value);
}
static bool TryEvaluateInt32 (BinaryOperator op, int l, int r, out long value)
{
int result;
if (EvaluateArithmeticWithOverflow.TryBinary (op.ToExpressionOperator (), l, r,
out result))
return true.With (result, out value);
return false.Without (out value);
}
bool TryEvaluateIndependent (BinaryOperator op, long l, long r, out long result)
{
switch (op) {
case BinaryOperator.And:
return true.With (l & r, out result);
case BinaryOperator.Ceq:
return true.With (ToInt (l == r), out result);
case BinaryOperator.Cne_Un:
return true.With (ToInt (l != r), out result);
case BinaryOperator.Cge:
return true.With (ToInt (l >= r), out result);
case BinaryOperator.Cgt:
return true.With (ToInt (l > r), out result);
case BinaryOperator.Cle:
return true.With (ToInt (l <= r), out result);
case BinaryOperator.Clt:
return true.With (ToInt (l < r), out result);
case BinaryOperator.LogicalAnd:
return true.With (ToInt (l != 0 && r != 0), out result);
case BinaryOperator.LogicalOr:
return true.With (ToInt (l != 0 || r != 0), out result);
case BinaryOperator.Or:
return true.With (l | r, out result);
case BinaryOperator.Xor:
return true.With (l ^ r, out result);
default:
return false.Without (out result);
}
}
static long ToInt (bool value)
{
return value ? 1 : 0;
}
static bool TryEvaluateToConstant (APC pc, BoxedExpression e, out long result)
{
int res;
if (e.IsConstantIntOrNull (out res))
return true.With (res, out result);
long argValue;
if (e.IsUnary && TryEvaluateToConstant (pc, e.UnaryArgument, out argValue)) {
switch (e.UnaryOperator) {
case UnaryOperator.Neg:
return true.With (-argValue, out result);
case UnaryOperator.Not:
return true.With (argValue != 0 ? 0L : 1L, out result);
default:
throw new ArgumentOutOfRangeException ();
}
}
return false.Without (out result);
}
}
}
}
}
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