Fix Type Info for Register Variable GEPs (#620)

* add test

* direct type of found variable by reg info

* weaker requirement on variable types

lib/Arch/Arch.cpp

@@ -311,6 +311,7 @@ void ArchBase::ForEachRegister(std::function<void(const Register *)> cb) const {
 // Return information about a register, given its name.
 const Register *ArchBase::RegisterByName(std::string_view name_) const {
   std::string name(name_.data(), name_.size());
+
   auto [curr_val_it, added] = reg_by_name.emplace(std::move(name), nullptr);
   if (added) {
     return nullptr;

lib/BC/InstructionLifter.cpp

@@ -87,7 +87,6 @@ LiftStatus InstructionLifter::LiftIntoBlock(Instruction &arch_inst,
                                             llvm::BasicBlock *block,
                                             llvm::Value *state_ptr,
                                             bool is_delayed) {
-  LOG(INFO) << "In instructionlifter";
   llvm::Function *const func = block->getParent();
   llvm::Module *const module = func->getParent();
   llvm::Function *isel_func = nullptr;
@@ -251,10 +250,18 @@ InstructionLifter::LoadRegAddress(llvm::BasicBlock *block,
     return reg_ptr_it->second;
   }
 
+
+  auto reg = impl->arch->RegisterByName(reg_name_);
+
   // It's already a variable in the function.
   const auto [var_ptr, var_ptr_type] = FindVarInFunction(func, reg_name_, true);
   if (var_ptr) {
-    reg_ptr_it->second = {var_ptr, var_ptr_type};
+    auto ty = var_ptr_type;
+    //NOTE(Ian) for stuff like NEXT_PC existing in the block we arent going to have reg type info, im not sure i like pulling it from var_ptr_type regardles. Not sure what to do about it
+    if (reg) {
+      ty = reg->type;
+    }
+    reg_ptr_it->second = {var_ptr, ty};
     return reg_ptr_it->second;
   }
 
@@ -262,7 +269,7 @@ InstructionLifter::LoadRegAddress(llvm::BasicBlock *block,
   // right now. We'll try to be careful about the placement of the actual
   // indexing instructions so that they always follow the definition of the
   // state pointer, and thus are most likely to dominate all future uses.
-  if (auto reg = impl->arch->RegisterByName(reg_name_)) {
+  if (reg) {
     llvm::Value *reg_ptr = nullptr;
 
     // The state pointer is an argument.

tests/Thumb/TestLifting.cpp

@@ -232,3 +232,25 @@ TEST(ThumbRandomizedLifts, RelPcTest) {
   TestSpecRunner runner(context);
   runner.RunTestSpec(spec);
 }
+
+TEST(RegressionTests, AARCH64RegSize) {
+  llvm::LLVMContext context;
+  context.enableOpaquePointers();
+  auto arch = remill::Arch::Build(&context, remill::OSName::kOSLinux,
+                                  remill::ArchName::kArchAArch64LittleEndian);
+  auto sems = remill::LoadArchSemantics(arch.get());
+  remill::IntrinsicTable instrinsics(sems.get());
+  auto op_lifter = arch->DefaultLifter(instrinsics);
+  auto target_lift = arch->DefineLiftedFunction("test_lift", sems.get());
+  auto st_ptr = remill::LoadStatePointer(target_lift);
+  CHECK_NOTNULL(st_ptr);
+  auto lifted =
+      op_lifter->LoadRegValue(&target_lift->getEntryBlock(), st_ptr, "W0");
+
+  CHECK_EQ(lifted->getType()->getIntegerBitWidth(), 32);
+  op_lifter->ClearCache();
+  auto lifted2 =
+      op_lifter->LoadRegValue(&target_lift->getEntryBlock(), st_ptr, "W0");
+
+  CHECK_EQ(lifted2->getType()->getIntegerBitWidth(), 32);
+}