Unfortunately, I didn't know this. Thanks for the info
On Friday, November 14, 2014 12:01:25 PM UTC, Andriy Tylychko wrote:
>
> I'm looking for all assignments to a specific fields and replace them by a
> call to a generated method passing the field by ref. The problem is that
> existing short form instructions can be invalidated because now distance
> between the instruction and its target can be too long for short form. It's
> just an example, I believe any modification that makes byte code bigger can
> lead to this problem.
>
> The solution is to change short-form to long-form. It's not so simple is
> easier to resolve this problem in generic way. So I modified Cecil code
> writing. Please check it and point to any problems. Please fill free to
> incorporate it in Cecil (with any modification) if you think it's useful.
>
> Two new methods of CodeWriter are:
>
> bool CorrectInstructions()
> {
> var instructions = body.Instructions;
> var items = instructions.items;
> var size = instructions.size;
>
> var anythingChanged = false;
> for (int i = 0; i < size; i++)
> {
> var instruction = items[i];
> anythingChanged |= CorrectInstructionShortForm(instruction);
> }
>
> return anythingChanged;
> }
>
> bool CorrectInstructionShortForm(Instruction instruction)
> {
> var opcode = instruction.OpCode;
> var operand = instruction.operand;
> switch (opcode.OperandType)
> {
> case OperandType.ShortInlineBrTarget:
> var target = (Instruction)instruction.operand;
> var offset = target.Offset - (instruction.Offset + opcode.Size
> + 1);
> if (offset > sbyte.MaxValue)
> {
> if (opcode != OpCodes.Leave_S)
> {
> const int diff = Code.Br - Code.Br_S;
> instruction.OpCode = new OpCode(opcode.Op1 << 0 | (
> opcode.Op2 + diff) << 8 | ((byte)opcode.Code + diff) << 16 | (byte)opcode.
> FlowControl << 24,
> (byte)OpCodeType.Macro << 0 | (byte)OperandType.
> InlineBrTarget << 8 | (byte)opcode.StackBehaviourPop << 16 | (byte)opcode.
> StackBehaviourPush << 24);
> }
> else
> {
> instruction.OpCode = new OpCode(opcode.Op1 << 0 | (
> opcode.Op2 - 1) << 8 | ((byte)opcode.Code - 1) << 16 | (byte)opcode.
> FlowControl << 24,
> (byte)OpCodeType.Primitive << 0 | (byte)
> OperandType.InlineBrTarget << 8 | (byte)opcode.StackBehaviourPop << 16 | (
> byte)opcode.StackBehaviourPush << 24);
> }
> }
> return true;
> case OperandType.ShortInlineVar:
> if (GetVariableIndex((VariableDefinition)operand) > byte.
> MaxValue)
> {
> var op2Diff = OpCodes.Ldloc.Op2 - OpCodes.Ldloc_S.Op2;
> const int codeDiff = Code.Ldloc - Code.Ldloc_S;
> instruction.OpCode = new OpCode(0xfe << 0 | (opcode.Op2 +
> op2Diff) << 8 | ((byte)opcode.Code + codeDiff) << 16 | (byte)opcode.
> FlowControl << 24,
> (byte)OpCodeType.Primitive << 0 |
> ...
--
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mono-cecil
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