[Bug] [Relax] Check failed: (it != this->var_arg_map_.end()) is false: Var is not defined

[Cookiee235]

Actual behavior

Traceback (most recent call last):
  File "/share_container/optfuzz/res/bugs/simple/res_undefined.py", line 49, in <module>
    compiled_after = compile_mod(relax.transform.LiftTransformParams()(mod))
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/share_container/optfuzz/res/bugs/simple/res_undefined.py", line 41, in compile_mod
    ex = relax.build(mod, target="llvm")
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/software/tvm-lunder/python/tvm/relax/vm_build.py", line 340, in build
    mod = _vmcodegen(builder, mod, exec_mode)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/software/tvm-lunder/python/tvm/relax/vm_build.py", line 176, in _vmcodegen
    return _ffi_api.VMCodeGen(builder, mod)  # type:ignore
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/software/tvm-lunder/python/tvm/_ffi/_ctypes/packed_func.py", line 240, in __call__
    raise_last_ffi_error()
  File "/software/tvm-lunder/python/tvm/_ffi/base.py", line 481, in raise_last_ffi_error
    raise py_err
tvm.error.InternalError: Traceback (most recent call last):
  7: tvm::runtime::PackedFuncObj::Extractor<tvm::runtime::PackedFuncSubObj<tvm::runtime::TypedPackedFunc<tvm::IRModule (tvm::relax::ExecBuilder, tvm::IRModule)>::AssignTypedLambda<tvm::IRModule (*)(tvm::relax::ExecBuilder, tvm::IRModule)>(tvm::IRModule (*)(tvm::relax::ExecBuilder, tvm::IRModule), std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)::{lambda(tvm::runtime::TVMArgs const&, tvm::runtime::TVMRetValue*)#1}> >::Call(tvm::runtime::PackedFuncObj const*, tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*)
  6: tvm::relax::relax_vm::VMCodeGen(tvm::relax::ExecBuilder, tvm::IRModule)
  5: tvm::relax::relax_vm::CodeGenVM::Run(tvm::relax::ExecBuilder, tvm::IRModule)
  4: tvm::relax::relax_vm::CodeGenVM::Codegen(tvm::relax::Function const&)
  3: tvm::relax::ExprFunctor<tvm::runtime::relax_vm::Instruction::Arg (tvm::RelayExpr const&)>::VisitExpr(tvm::RelayExpr const&)
  2: tvm::relax::relax_vm::CodeGenVM::VisitExpr_(tvm::relax::SeqExprNode const*)
  1: tvm::relax::ExprFunctor<tvm::runtime::relax_vm::Instruction::Arg (tvm::RelayExpr const&)>::VisitExpr(tvm::RelayExpr const&)
  0: tvm::relax::relax_vm::CodeGenVM::VisitExpr_(tvm::relax::VarNode const*)
  File "/software/tvm-lunder/src/relax/backend/vm/codegen_vm.cc", line 232
InternalError: Check failed: (it != this->var_arg_map_.end()) is false: Var w1_t is not defined

Steps to reproduce

import tvm
from tvm import relax
import numpy as np
from tvm.script import ir as I
from tvm.script import tir as T
from tvm.script import relax as R

@I.ir_module
class Module:
    @T.prim_func(private=True)
    def transpose(w1: T.Buffer((T.int64(256), T.int64(256)), "float32"), T_transpose: T.Buffer((T.int64(256), T.int64(256)), "float32")):
        T.func_attr({"tir.noalias": T.bool(True)})
        # with T.block("root"):
        for ax0, ax1 in T.grid(T.int64(256), T.int64(256)):
            with T.block("T_transpose"):
                v_ax0, v_ax1 = T.axis.remap("SS", [ax0, ax1])
                T.reads(w1[v_ax1, v_ax0])
                T.writes(T_transpose[v_ax0, v_ax1])
                T_transpose[v_ax0, v_ax1] = w1[v_ax1, v_ax0]

    @R.function(private=False)
    def main(x: R.Tensor((256, 256), dtype="float32"), w1: R.Tensor((256, 256), dtype="float32")) -> R.Tensor((256, 256), dtype="float32"):
        R.func_attr({"num_input": 1})
        cls = Module
        with R.dataflow():
            w1_t = R.call_tir(cls.transpose, (w1,), out_sinfo=R.Tensor((256, 256), dtype="float32"))
            R.output(w1_t)
        return w1_t

mod = Module
mod.show()
mod = tvm.relax.transform.LegalizeOps()(mod)

input_0 = tvm.nd.array(10 * np.random.random([256, 256]).astype('float32'))
input_1 = tvm.nd.array(10 * np.random.random([256, 256]).astype('float32'))

def compile_mod(mod):
    mod = relax.transform.FuseTIR()(mod)
    mod = relax.transform.LambdaLift()(mod)
    ex = relax.build(mod, target="llvm")
    vm = relax.VirtualMachine(ex, tvm.cpu())
    return vm

compiled_before = compile_mod(mod)
before_outputs = compiled_before["main"](input_0, input_1)

compiled_after = compile_mod(relax.transform.LiftTransformParams()(mod))
transformed_weights = compiled_after["main_transform_params"]([input_1])
after_outputs = compiled_after["main"](input_0, *transformed_weights)

cc @Lunderberg @junrushao

[Lunderberg]

Looks like a bug in the LiftTransformParams implementation, that it only determines the variables required at runtime based on the contents of VarBinding, and not from the output of a Function. Should be fixed in https://github.com/apache/tvm/pull/17232.

[Cookiee235]

@Lunderberg The test case can run correctly now under the given PR (#17232). Thanks for your efforts!

[Lunderberg]

No problem, and thank you for the high-quality bug reports! Running into any of these failure modes in larger use cases can be very difficult to debug. My personal rule of thumb is that every IRModule should either be caught as ill-formed, or should compile without issue. The errors you've been uncovering show that that clearly isn't the current case, but fixing them helps move toward that ideal.

(With some exceptions for uncatchable issues, such as incorrect arguments used for external functions.)