/*
* Replace block @block with an `isinst`, but keep @index instructions at the beginning
* of the block and the (optional) branch at the end.
*
* The block is expected to contain the following:
*
* - optional simple load instruction
* - conditional call
* - optional branch instruction
*
*/
public void ReplaceWithIsInst(ref BasicBlock block, int index, TypeDefinition type)
{
if (index < 0 || index >= block.Count)
{
throw new ArgumentOutOfRangeException(nameof(index));
}
if (block.Instructions [index].OpCode.Code != Code.Call)
{
DebugHelpers.AssertFailUnexpected(Method, block, block.Instructions [index]);
}
/*
* The block consists of the following:
*
* - optional simple load instruction
* - conditional call
* - optional branch instruction
*
*/
var reference = Method.DeclaringType.Module.ImportReference(type);
BlockList.ReplaceInstructionAt(ref block, index++, Instruction.Create(OpCodes.Isinst, reference));
switch (block.BranchType)
{
case BranchType.False:
case BranchType.True:
DebugHelpers.Assert(index == block.Count - 1);
break;
case BranchType.None:
// Convert it into a bool.
DebugHelpers.Assert(index == block.Count);
BlockList.InsertInstructionAt(ref block, index++, Instruction.Create(OpCodes.Ldnull));
BlockList.InsertInstructionAt(ref block, index++, Instruction.Create(OpCodes.Cgt_Un));
break;
case BranchType.Return:
// Convert it into a bool.
DebugHelpers.Assert(index == block.Count - 1);
BlockList.InsertInstructionAt(ref block, index++, Instruction.Create(OpCodes.Ldnull));
BlockList.InsertInstructionAt(ref block, index++, Instruction.Create(OpCodes.Cgt_Un));
break;
default:
throw DebugHelpers.AssertFailUnexpected(Method, block, block.BranchType);
}
BlockList.TryMergeBlock(ref block);
}