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/*
* MRustC - Rust Compiler
* - By John Hodge (Mutabah/thePowersGang)
*
* mir/cleanup.cpp
* - MIR Cleanup
*
* Removes artefacts left after monomorphisation
* - Converts <Trait as Trait>::method() into a vtable call
* - Replaces constants by their value
*/
#include "main_bindings.hpp"
#include "mir.hpp"
#include <hir/visitor.hpp>
#include <hir_typeck/static.hpp>
#include <mir/helpers.hpp>
void MIR_Cleanup(const StaticTraitResolve& resolve, const ::HIR::ItemPath& path, ::MIR::Function& fcn, const ::HIR::Function::args_t& args, const ::HIR::TypeRef& ret_type)
{
Span sp;
::MIR::TypeResolve state { sp, resolve, FMT_CB(ss, ss << path;), ret_type, args, fcn };
for(auto& block : fcn.blocks)
{
for(auto& stmt : block.statements)
{
if( stmt.is_Assign() )
{
auto& se = stmt.as_Assign();
TU_IFLET( ::MIR::RValue, se.src, Constant, e,
// TODO: Replace `Const` with actual values
)
}
}
TU_IFLET( ::MIR::Terminator, block.terminator, CallPath, e,
// Detect calling `<Trait as Trait>::method()` and replace with vtable call
if( e.fcn_path.m_data.is_UfcsKnown() && e.fcn_path.m_data.as_UfcsKnown().type->m_data.is_TraitObject() )
{
const auto& pe = e.fcn_path.m_data.as_UfcsKnown();
const auto& te = pe.type->m_data.as_TraitObject();
// TODO: What if the method is from a supertrait?
if( pe.trait == te.m_trait.m_path )
{
assert( te.m_trait.m_trait_ptr );
const auto& trait = *te.m_trait.m_trait_ptr;
// 1. Get the vtable index for this function
if( trait.m_value_indexes.count(pe.item) == 0 )
BUG(sp, "Calling method '" << pe.item << "' of " << pe.trait << " which isn't in the vtable");
unsigned int vtable_idx = trait.m_value_indexes.at( pe.item );
// 2. Load from the vtable
auto vtable_ty_spath = pe.trait.m_path;
vtable_ty_spath.m_components.back() += "#vtable";
const auto& vtable_ref = resolve.m_crate.get_struct_by_path(sp, vtable_ty_spath);
// Copy the param set from the trait in the trait object
::HIR::PathParams vtable_params = te.m_trait.m_path.m_params.clone();
// - Include associated types on bound
for(const auto& ty_b : te.m_trait.m_type_bounds) {
auto idx = trait.m_type_indexes.at(ty_b.first);
if(vtable_params.m_types.size() <= idx)
vtable_params.m_types.resize(idx+1);
vtable_params.m_types[idx] = ty_b.second.clone();
}
auto vtable_ty = ::HIR::TypeRef::new_pointer(
::HIR::BorrowType::Shared,
::HIR::TypeRef( ::HIR::GenericPath(vtable_ty_spath, mv$(vtable_params)), &vtable_ref )
);
// Allocate a temporary for the vtable pointer itself
auto vtable_lv = ::MIR::LValue::make_Temporary({ static_cast<unsigned int>(fcn.temporaries.size()) });
fcn.temporaries.push_back( mv$(vtable_ty) );
// - Load the vtable and store it
auto vtable_rval = ::MIR::RValue::make_DstMeta({
::MIR::LValue::make_Deref({ box$(e.args.front().clone()) })
});
block.statements.push_back( ::MIR::Statement::make_Assign({ vtable_lv.clone(), mv$(vtable_rval) }) );
// Update the terminator with the new information.
auto vtable_fcn = ::MIR::LValue::make_Field({ box$(::MIR::LValue::make_Deref({ box$(vtable_lv) })), vtable_idx });
auto new_term = ::MIR::Terminator::make_CallValue({
e.ret_block, e.panic_block,
mv$(e.ret_val), mv$(vtable_fcn),
mv$(e.args)
});
block.terminator = mv$(new_term);
}
}
)
}
}
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