LAB2 Build Fail Error

[JongyCysec]

Fail Case 1 (using foreign crate)

In the implementation of bht and btb, I've used clog2 function in order to calculate bit width corresponding to BHT_ENTRIES or BTB_ENTRIES.
However, it caused error like below.

thread 'rustc' panicked at hazardflow/src/compiler/pure/build_expr_ast.rs:731:77:
unimplemented

So I suspect that using foreign function like clog2 should be refrained.

Fail Case 2 (return statement)

If we end up function with return statement without any condition, then it raise build error as below.

thread 'rustc' panicked at hazardflow/src/compiler/pure/function.rs:741:25:
explicit return with no path conditions

So, we should also refrain from using pure return statement.
ex. return x; -> x

Fail Case 3 (into trait)

I tried to add pc and imm whose types are u32 and U<N>.
So, I tried to change the type of imm into u32 by using .into(). But I suspect that compiler prohibited using into trait.

thread 'rustc' panicked at hazardflow/src/compiler/pure/build_expr_ast.rs:765:25:
not yet implemented: Implement Into trait

Therefore, finally I've used from trait instead.

[minseongg]

Sorry.. it seems the current HazardFlow compiler is immature, there are some unimplemented features.

For the first failure case, the clog2() function can only be used in const generic parameters. To workaround the failure case, please use APIs that can use clog2() within the const generics. For example, if you are calculating index bits, you can use clip_const::<M>(index) API, where M is an { clog2(ENTRIES) }.