private static int ContractStartInMoveNext(ContractNodes contractNodes, Method moveNext, out int statementIndex,
Method origMethod)
{
Contract.Requires(contractNodes != null);
Contract.Requires(moveNext != null);
Contract.Requires(moveNext.Body != null);
Contract.Requires(moveNext.Body.Statements != null);
Contract.Ensures(Contract.ValueAtReturn(out statementIndex) >= 0);
Contract.Ensures(Contract.Result<int>() >= -1);
Contract.Ensures(Contract.Result<int>() < moveNext.Body.Statements.Count);
Block body = moveNext.Body;
bool isAsync = moveNext.IsAsync;
statementIndex = 0;
var blocks = body.Statements;
bool stateIsRead = false;
var fieldScanner = new HelperMethods.ExpressionScanner((field, isStore) =>
{
if (isStore) return;
if (field != null && field.Name != null && field.Name.Name.Contains("<>") &&
field.Name.Name.Contains("__state"))
{
stateIsRead = true;
}
});
fieldScanner.Visit(body.Statements);
// Dictionary tracks local variable values and a bit saying if the value is the state (in that case it is 0).
Dictionary<Variable, Pair<int, EvalKind>> env = new Dictionary<Variable, Pair<int, EvalKind>>();
int currentBlockIndex = 0;
bool seenFinalCompare = false;
bool lastBranchNonConditional = false;
while (currentBlockIndex >= 0 && currentBlockIndex < blocks.Count)
{
var block = blocks[currentBlockIndex] as Block;
if (block == null || block.Statements == null) continue;
for (int i = 0; i < block.Statements.Count; i++)
{
var stmt = block.Statements[i];
if (stmt == null) continue;
if (contractNodes.IsContractOrValidatorOrAbbreviatorCall(stmt))
{
statementIndex = i;
return currentBlockIndex;
}
Branch branch = stmt as Branch;
if (branch != null)
{
if (branch.Condition == null)
{
currentBlockIndex = FindTargetBlock(blocks, branch.Target, currentBlockIndex);
lastBranchNonConditional = true;
goto OuterLoop;
}
var value = EvaluateExpression(branch.Condition, env, seenFinalCompare, isAsync);
if (value.Two == EvalKind.IsDisposingTest)
{
if (value.One != 0)
{
return FindTargetBlock(blocks, branch.Target, currentBlockIndex);
}
if (i + 1 < block.Statements.Count)
{
statementIndex = i + 1;
return currentBlockIndex;
}
if (currentBlockIndex + 1 < body.Statements.Count)
{
return currentBlockIndex + 1;
}
return -1;
}
if (seenFinalCompare)
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
seenFinalCompare = (value.Two == EvalKind.IsFinalCompare || value.Two == EvalKind.IsStateValue);
if (value.One != 0)
{
currentBlockIndex = FindTargetBlock(blocks, branch.Target, currentBlockIndex);
goto OuterLoop;
}
continue;
}
if (isAsync && lastBranchNonConditional)
{
// not a branch and last one was non-conditional
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
var swtch = stmt as SwitchInstruction;
if (swtch != null)
{
if (seenFinalCompare)
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
var value = EvaluateExpression(swtch.Expression, env, seenFinalCompare, isAsync);
if (value.One < 0 || swtch.Targets == null || value.One >= swtch.Targets.Count)
{
// fall through
if (isAsync)
{
seenFinalCompare = true;
}
continue;
}
currentBlockIndex = FindTargetBlock(blocks, swtch.Targets[value.One], currentBlockIndex);
// assume seen final compare
seenFinalCompare = true;
goto OuterLoop;
}
if (HelperMethods.IsClosureCreation(origMethod, stmt) != null)
{
// end of trace
statementIndex = i;
return currentBlockIndex;
}
AssignmentStatement assign = stmt as AssignmentStatement;
if (assign != null)
{
if (assign.Source is ConstructArray)
{
// treat as beginning of contract (typically a params array)
statementIndex = i;
return currentBlockIndex;
}
var value = EvaluateExpression(assign.Source, env, seenFinalCompare, isAsync);
if (IsThisDotState(assign.Target))
{
// end of trace
if (i + 1 < block.Statements.Count)
{
statementIndex = i + 1;
return currentBlockIndex;
}
if (currentBlockIndex + 1 < body.Statements.Count)
{
return currentBlockIndex + 1;
}
return -1;
}
if (IsDoFinallyBodies(assign.Target) && !stateIsRead)
{
// end of trace
if (i + 1 < block.Statements.Count)
{
statementIndex = i + 1;
return currentBlockIndex;
}
if (currentBlockIndex + 1 < body.Statements.Count)
{
return currentBlockIndex + 1;
}
return -1;
}
var target = assign.Target as Variable;
if (target != null) env[target] = value;
if (seenFinalCompare && !(value.Two == EvalKind.IsDisposingTest))
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
continue;
}
if (seenFinalCompare)
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
switch (stmt.NodeType)
{
case NodeType.Nop:
case NodeType.ExpressionStatement:
// skip: C# compiler emits funky pushes then pops
break;
default:
Contract.Assume(false, string.Format("Unexpected node type '{0}'", stmt.NodeType));
return -1;
}
}
// next block in body
currentBlockIndex++;
OuterLoop:
;
}
return -1;
}
private static int ContractStartInMoveNext(ContractNodes contractNodes, Method moveNext, out int statementIndex,
Method origMethod)
{
Contract.Requires(contractNodes != null);
Contract.Requires(moveNext != null);
Contract.Requires(moveNext.Body != null);
Contract.Requires(moveNext.Body.Statements != null);
Contract.Ensures(Contract.ValueAtReturn(out statementIndex) >= 0);
Contract.Ensures(Contract.Result<int>() >= -1);
Contract.Ensures(Contract.Result<int>() < moveNext.Body.Statements.Count);
Block body = moveNext.Body;
bool isAsync = moveNext.IsAsync;
statementIndex = 0;
var blocks = body.Statements;
bool stateIsRead = false;
var fieldScanner = new HelperMethods.ExpressionScanner((field, isStore) =>
{
if (isStore) return;
if (field != null && field.Name != null && field.Name.Name.Contains("<>") &&
field.Name.Name.Contains("__state"))
{
stateIsRead = true;
}
});
fieldScanner.Visit(body.Statements);
// Dictionary tracks local variable values and a bit saying if the value is the state (in that case it is 0).
Dictionary<Variable, Pair<int, EvalKind>> env = new Dictionary<Variable, Pair<int, EvalKind>>();
int currentBlockIndex = 0;
bool seenFinalCompare = false;
bool lastBranchNonConditional = false;
while (currentBlockIndex >= 0 && currentBlockIndex < blocks.Count)
{
var block = blocks[currentBlockIndex] as Block;
if (block == null || block.Statements == null) continue;
for (int i = 0; i < block.Statements.Count; i++)
{
var stmt = block.Statements[i];
if (stmt == null) continue;
if (contractNodes.IsContractOrValidatorOrAbbreviatorCall(stmt))
{
statementIndex = i;
return currentBlockIndex;
}
Branch branch = stmt as Branch;
if (branch != null)
{
if (branch.Condition == null)
{
currentBlockIndex = FindTargetBlock(blocks, branch.Target, currentBlockIndex);
lastBranchNonConditional = true;
goto OuterLoop;
}
// Roslyn-based compiler introduced new pattern for async methods with 2 await statements.
// Current implementation sets seenFinalCompare to true when `if (num != 0)` code was found in the MoveNext method.
// This usually meant that async preamble is finished and next statement could be a contract statement
// (or legacy contract statement, doesn't matter).
// But VS2015 compiler changes the behavior and right after `if (num != 0)` there another check that should be skipped.
// Please see additional comments at IsRoslynStateCheckForSecondFinishedAwaiter
if (seenFinalCompare && isAsync && IsRoslynStateCheckForSecondFinishedAwaiter(branch.Condition, env, ignoreUnknown: true))
{
// just skipping current statement!
continue;
}
var value = EvaluateExpression(branch.Condition, env, seenFinalCompare, isAsync);
if (value.Two == EvalKind.IsDisposingTest)
{
if (value.One != 0)
{
return FindTargetBlock(blocks, branch.Target, currentBlockIndex);
}
if (i + 1 < block.Statements.Count)
{
statementIndex = i + 1;
return currentBlockIndex;
}
if (currentBlockIndex + 1 < body.Statements.Count)
{
return currentBlockIndex + 1;
}
return -1;
}
if (seenFinalCompare)
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
seenFinalCompare = (value.Two == EvalKind.IsFinalCompare || value.Two == EvalKind.IsStateValue);
if (value.One != 0)
{
currentBlockIndex = FindTargetBlock(blocks, branch.Target, currentBlockIndex);
goto OuterLoop;
}
continue;
}
if (isAsync && lastBranchNonConditional)
{
// not a branch and last one was non-conditional
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
var swtch = stmt as SwitchInstruction;
if (swtch != null)
{
if (seenFinalCompare)
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
var value = EvaluateExpression(swtch.Expression, env, seenFinalCompare, isAsync);
if (value.One < 0 || swtch.Targets == null || value.One >= swtch.Targets.Count)
{
// fall through
if (isAsync)
{
seenFinalCompare = true;
}
continue;
}
currentBlockIndex = FindTargetBlock(blocks, swtch.Targets[value.One], currentBlockIndex);
// assume seen final compare
seenFinalCompare = true;
goto OuterLoop;
}
if (HelperMethods.IsClosureCreation(origMethod, stmt) != null)
{
// end of trace
statementIndex = i;
return currentBlockIndex;
}
AssignmentStatement assign = stmt as AssignmentStatement;
if (assign != null)
{
if (assign.Source is ConstructArray)
{
// treat as beginning of contract (typically a params array)
statementIndex = i;
return currentBlockIndex;
}
// Roslyn-based compiler will generate AssignmentStatement with
// Pop as a source node (any complex if-statement will do this).
// This type of node will lead to
// InvalidOperationException in the EvaluateExpression method.
// This if statement avoids the failure and fixes #172.
if (assign.Source.NodeType == NodeType.Pop)
continue;
var value = EvaluateExpression(assign.Source, env, seenFinalCompare, isAsync);
if (IsThisDotState(assign.Target))
{
// end of trace
if (i + 1 < block.Statements.Count)
{
statementIndex = i + 1;
return currentBlockIndex;
}
if (currentBlockIndex + 1 < body.Statements.Count)
{
return currentBlockIndex + 1;
}
return -1;
}
if (IsDoFinallyBodies(assign.Target) && !stateIsRead)
{
// end of trace
if (i + 1 < block.Statements.Count)
{
statementIndex = i + 1;
return currentBlockIndex;
}
if (currentBlockIndex + 1 < body.Statements.Count)
{
return currentBlockIndex + 1;
}
return -1;
}
var target = assign.Target as Variable;
if (target != null) env[target] = value;
if (seenFinalCompare && !(value.Two == EvalKind.IsDisposingTest))
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
continue;
}
if (seenFinalCompare)
{
// must be the end.
statementIndex = i;
return currentBlockIndex;
}
switch (stmt.NodeType)
{
case NodeType.Nop:
case NodeType.ExpressionStatement:
// skip: C# compiler emits funky pushes then pops
break;
default:
Contract.Assume(false, string.Format("Unexpected node type '{0}'", stmt.NodeType));
return -1;
}
}
// next block in body
currentBlockIndex++;
OuterLoop:
;
}
return -1;
}
