public void DecompileFunction(StreamWriter output, int functionIndex)
{
FunctionBody body = WasmModule.FunctionBodies[functionIndex];
FunctionSignature signature = WasmModule.FunctionTypes[WasmModule.Functions[functionIndex]];
// get IR
var context = new IntermediateContext(signature, WasmModule, output);
List <IntermediateInstruction> instructions = new IntermediateConverter(WasmModule, body, signature).Convert();
output.Write(signature.ToString($"fun_{functionIndex:X8}"));
output.WriteLine(" {");
// write all IR while simulating the stack
foreach (IntermediateInstruction instruction in instructions)
{
HandleInstruction(ref context, instruction);
}
output.WriteLine("}");
if (context.Indentation != 0)
{
throw new Exception("Function body has unbalanced indentation");
}
if (context.Stack.Count != 0)
{
throw new Exception($"Unbalanced stack, found {context.Stack.Count} remaining values");
}
output.WriteLine();
}
private static void HandleInstruction(ref IntermediateContext context, IntermediateInstruction instruction)
{
if (context.RestOfBlockUnreachable && instruction.IsImplicit)
{
#if DEBUG
context.WriteFull("// omitted implicit instruction because rest of block is unreachable");
#endif
return;
}
var args = new Variable[instruction.PopCount];
for (int i = 0; i < instruction.PopCount; i++)
{
args[i] = context.Pop();
Debug.Assert(instruction.PopTypes[i] == args[i].Type || instruction.PopTypes[i] == ValueKind.Any || args[i].Type == ValueKind.Any);
}
context.RestOfBlockUnreachable = instruction.RestOfBlockUnreachable;
// NOTE: really ugly and slow, but can't be replaced with string.format since input is dynamic and can contain {}
string s = instruction.OperationStringFormat.SafeFormat(args);
Debug.Assert(instruction.PushCount <= 1);
if (instruction.PushCount > 0)
{
s = $"{context.Push(instruction.PushTypes[0])} = {s}";
}
if (instruction.HasBlock)
{
s += " {";
}
if (instruction.Comment != null)
{
s += " // " + instruction.Comment;
}
context.WriteFull(s);
if (instruction.HasBlock)
{
HandleBlock(ref context, instruction.Block1 !);
if (instruction.Block2 != null)
{
context.WriteFull("} else {");
HandleBlock(ref context, instruction.Block2);
}
context.WriteFull("}");
}
static void HandleBlock(ref IntermediateContext context2, in ControlBlock block)
