serene/libserene/lib/jit/packer.cpp

97 lines
3.6 KiB
C++

/* -*- C++ -*-
* Serene Programming Language
*
* Copyright (c) 2019-2022 Sameer Rahmani <lxsameer@gnu.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "serene/jit/packer.h"
#include "serene/config.h"
#include <llvm/IR/IRBuilder.h>
namespace serene::jit {
std::string makePackedFunctionName(llvm::StringRef name) {
// TODO: move the "_serene_" constant to a macro or something
return PACKED_FUNCTION_NAME_PREFIX + name.str();
}
void packFunctionArguments(llvm::Module *module) {
auto &ctx = module->getContext();
llvm::IRBuilder<> builder(ctx);
llvm::DenseSet<llvm::Function *> interfaceFunctions;
for (auto &func : module->getFunctionList()) {
if (func.isDeclaration()) {
continue;
}
if (interfaceFunctions.count(&func) != 0) {
continue;
}
// Given a function `foo(<...>)`, define the interface function
// `serene_foo(i8**)`.
auto *newType = llvm::FunctionType::get(
builder.getVoidTy(), builder.getInt8PtrTy()->getPointerTo(),
/*isVarArg=*/false);
auto newName = makePackedFunctionName(func.getName());
auto funcCst = module->getOrInsertFunction(newName, newType);
llvm::Function *interfaceFunc =
llvm::cast<llvm::Function>(funcCst.getCallee());
interfaceFunctions.insert(interfaceFunc);
// Extract the arguments from the type-erased argument list and cast them to
// the proper types.
auto *bb = llvm::BasicBlock::Create(ctx);
bb->insertInto(interfaceFunc);
builder.SetInsertPoint(bb);
llvm::Value *argList = interfaceFunc->arg_begin();
llvm::SmallVector<llvm::Value *, COMMON_ARGS_COUNT> args;
args.reserve(llvm::size(func.args()));
for (const auto &indexedArg : llvm::enumerate(func.args())) {
llvm::Value *argIndex = llvm::Constant::getIntegerValue(
builder.getInt64Ty(), llvm::APInt(I64_SIZE, indexedArg.index()));
llvm::Value *argPtrPtr =
builder.CreateGEP(builder.getInt8PtrTy(), argList, argIndex);
llvm::Value *argPtr =
builder.CreateLoad(builder.getInt8PtrTy(), argPtrPtr);
llvm::Type *argTy = indexedArg.value().getType();
argPtr = builder.CreateBitCast(argPtr, argTy->getPointerTo());
llvm::Value *arg = builder.CreateLoad(argTy, argPtr);
args.push_back(arg);
}
// Call the implementation function with the extracted arguments.
llvm::Value *result = builder.CreateCall(&func, args);
// Assuming the result is one value, potentially of type `void`.
if (!result->getType()->isVoidTy()) {
llvm::Value *retIndex = llvm::Constant::getIntegerValue(
builder.getInt64Ty(), llvm::APInt(I64_SIZE, llvm::size(func.args())));
llvm::Value *retPtrPtr =
builder.CreateGEP(builder.getInt8PtrTy(), argList, retIndex);
llvm::Value *retPtr =
builder.CreateLoad(builder.getInt8PtrTy(), retPtrPtr);
retPtr = builder.CreateBitCast(retPtr, result->getType()->getPointerTo());
builder.CreateStore(result, retPtr);
}
// The interface function returns void.
builder.CreateRetVoid();
}
};
} // namespace serene::jit