1 //===-- RenderScriptx86ABIFixups.cpp ----------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
14 // Other libraries and framework includes
15 #include "llvm/ADT/StringRef.h"
16 #include "llvm/IR/BasicBlock.h"
17 #include "llvm/IR/CallSite.h"
18 #include "llvm/IR/Constants.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/Instruction.h"
21 #include "llvm/IR/Instructions.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/IRReader/IRReader.h"
24 #include "llvm/Pass.h"
27 #include "lldb/Core/Log.h"
28 #include "lldb/Target/Process.h"
30 using namespace lldb_private;
33 bool isRSAPICall(llvm::Module &module, llvm::CallInst *call_inst) {
34 // TODO get the list of renderscript modules from lldb and check if
35 // this llvm::Module calls into any of them.
37 const auto func_name = call_inst->getCalledFunction()->getName();
38 if (func_name.startswith("llvm") || func_name.startswith("lldb"))
41 if (call_inst->getCalledFunction()->isIntrinsic())
47 bool isRSLargeReturnCall(llvm::Module &module, llvm::CallInst *call_inst) {
48 // i686 and x86_64 returns for large vectors in the RenderScript API are not
50 // register pairs, but as a hidden sret type. This is not reflected in the
51 // debug info or mangled
52 // symbol name, and the android ABI for x86 and x86_64, (as well as the
53 // emulators) specifies there is
54 // no AVX, so bcc generates an sret function because we cannot natively return
56 // This function simply checks whether a function has a > 128bit return type.
58 // unreliable heuristic, and relies on bcc not generating AVX code, so if the
59 // android ABI one day
60 // provides for AVX, this function may go out of fashion.
62 if (!call_inst || !call_inst->getCalledFunction())
65 return call_inst->getCalledFunction()
67 ->getPrimitiveSizeInBits() > 128;
70 bool isRSAllocationPtrTy(const llvm::Type *type) {
71 if (!type->isPointerTy())
73 auto ptr_type = type->getPointerElementType();
75 return ptr_type->isStructTy() &&
76 ptr_type->getStructName().startswith("struct.rs_allocation");
79 bool isRSAllocationTyCallSite(llvm::Module &module, llvm::CallInst *call_inst) {
81 if (!call_inst->hasByValArgument())
83 for (const auto ¶m : call_inst->operand_values())
84 if (isRSAllocationPtrTy(param->getType()))
89 llvm::FunctionType *cloneToStructRetFnTy(llvm::CallInst *call_inst) {
90 // on x86 StructReturn functions return a pointer to the return value, rather
92 // value itself [ref](http://www.agner.org/optimize/calling_conventions.pdf
94 // We create a return type by getting the pointer type of the old return type,
95 // and inserting a new
96 // initial argument of pointer type of the original return type.
98 GetLogIfAnyCategoriesSet(LIBLLDB_LOG_LANGUAGE | LIBLLDB_LOG_EXPRESSIONS));
100 assert(call_inst && "no CallInst");
101 llvm::Function *orig = call_inst->getCalledFunction();
102 assert(orig && "CallInst has no called function");
103 llvm::FunctionType *orig_type = orig->getFunctionType();
104 auto name = orig->getName();
106 log->Printf("%s - cloning to StructRet function for '%s'", __FUNCTION__,
109 unsigned num_params = orig_type->getNumParams();
110 std::vector<llvm::Type *> new_params{num_params + 1, nullptr};
111 std::vector<llvm::Type *> params{orig_type->param_begin(),
112 orig_type->param_end()};
114 // This may not work if the function is somehow declared void as llvm is
116 // and represents void* with i8*
117 assert(!orig_type->getReturnType()->isVoidTy() &&
118 "Cannot add StructRet attribute to void function");
119 llvm::PointerType *return_type_ptr_type =
120 llvm::PointerType::getUnqual(orig->getReturnType());
121 assert(return_type_ptr_type &&
122 "failed to get function return type PointerType");
123 if (!return_type_ptr_type)
127 log->Printf("%s - return type pointer type for StructRet clone @ '0x%p':\n",
128 __FUNCTION__, (void *)return_type_ptr_type);
129 // put the the sret pointer argument in place at the beginning of the argument
131 params.emplace(params.begin(), return_type_ptr_type);
132 assert(params.size() == num_params + 1);
133 return llvm::FunctionType::get(return_type_ptr_type, params,
137 bool findRSCallSites(llvm::Module &module,
138 std::set<llvm::CallInst *> &rs_callsites,
139 bool (*predicate)(llvm::Module &, llvm::CallInst *)) {
142 for (auto &func : module.getFunctionList())
143 for (auto &block : func.getBasicBlockList())
144 for (auto &inst : block) {
145 llvm::CallInst *call_inst =
146 llvm::dyn_cast_or_null<llvm::CallInst>(&inst);
147 if (!call_inst || !call_inst->getCalledFunction())
148 // This is not the call-site you are looking for...
150 if (isRSAPICall(module, call_inst) && predicate(module, call_inst)) {
151 rs_callsites.insert(call_inst);
158 bool fixupX86StructRetCalls(llvm::Module &module) {
159 bool changed = false;
160 // changing a basic block while iterating over it seems to have some undefined
162 // going on so we find all RS callsites first, then fix them up after
165 std::set<llvm::CallInst *> rs_callsites;
166 if (!findRSCallSites(module, rs_callsites, isRSLargeReturnCall))
169 for (auto call_inst : rs_callsites) {
170 llvm::FunctionType *new_func_type = cloneToStructRetFnTy(call_inst);
171 assert(new_func_type &&
172 "failed to clone functionType for Renderscript ABI fixup");
174 llvm::CallSite call_site(call_inst);
175 llvm::Function *func = call_inst->getCalledFunction();
176 assert(func && "cannot resolve function in RenderScriptRuntime");
177 // Copy the original call arguments
178 std::vector<llvm::Value *> new_call_args(call_site.arg_begin(),
179 call_site.arg_end());
181 // Allocate enough space to store the return value of the original function
182 // we pass a pointer to this allocation as the StructRet param, and then
184 // value into the lldb return value
185 llvm::AllocaInst *return_value_alloc = new llvm::AllocaInst(
186 func->getReturnType(), "var_vector_return_alloc", call_inst);
187 // use the new allocation as the new first argument
188 new_call_args.emplace(new_call_args.begin(),
189 llvm::cast<llvm::Value>(return_value_alloc));
190 llvm::PointerType *new_func_ptr_type =
191 llvm::PointerType::get(new_func_type, 0);
192 // Create the type cast from the old function type to the new one
193 llvm::Constant *new_func_cast = llvm::ConstantExpr::getCast(
194 llvm::Instruction::BitCast, func, new_func_ptr_type);
195 // create an allocation for a new function pointer
196 llvm::AllocaInst *new_func_ptr =
197 new llvm::AllocaInst(new_func_ptr_type, "new_func_ptr", call_inst);
198 // store the new_func_cast to the newly allocated space
199 (new llvm::StoreInst(new_func_cast, new_func_ptr, call_inst))
200 ->setName("new_func_ptr_load_cast");
201 // load the new function address ready for a jump
202 llvm::LoadInst *new_func_addr_load =
203 new llvm::LoadInst(new_func_ptr, "load_func_pointer", call_inst);
204 // and create a callinstruction from it
205 llvm::CallInst *new_call_inst = llvm::CallInst::Create(
206 new_func_addr_load, new_call_args, "new_func_call", call_inst);
207 new_call_inst->setCallingConv(call_inst->getCallingConv());
208 new_call_inst->setTailCall(call_inst->isTailCall());
209 llvm::LoadInst *lldb_save_result_address =
210 new llvm::LoadInst(return_value_alloc, "save_return_val", call_inst);
212 // Now remove the old broken call
213 call_inst->replaceAllUsesWith(lldb_save_result_address);
214 call_inst->eraseFromParent();
220 bool fixupRSAllocationStructByValCalls(llvm::Module &module) {
221 // On x86_64, calls to functions in the RS runtime that take an
222 // `rs_allocation` type argument
223 // are actually handled as by-ref params by bcc, but appear to be passed by
224 // value by lldb (the callsite all use
226 // On x86_64 Linux, struct arguments are transferred in registers if the
227 // struct size is no bigger than
228 // 128bits [ref](http://www.agner.org/optimize/calling_conventions.pdf)
229 // section 7.1 "Passing and returning objects"
230 // otherwise passed on the stack.
231 // an object of type `rs_allocation` is actually 256bits, so should be passed
232 // on the stack. However, code generated
233 // by bcc actually treats formal params of type `rs_allocation` as
234 // `rs_allocation *` so we need to convert the
235 // calling convention to pass by reference, and remove any hint of byval from
236 // formal parameters.
237 bool changed = false;
238 std::set<llvm::CallInst *> rs_callsites;
239 if (!findRSCallSites(module, rs_callsites, isRSAllocationTyCallSite))
242 std::set<llvm::Function *> rs_functions;
244 // for all call instructions
245 for (auto call_inst : rs_callsites) {
246 // add the called function to a set so that we can strip its byval
247 // attributes in another pass
248 rs_functions.insert(call_inst->getCalledFunction());
250 // get the function attributes
251 llvm::AttributeSet call_attribs = call_inst->getAttributes();
253 // iterate over the argument attributes
254 for (size_t i = 1; i <= call_attribs.getNumSlots(); ++i) {
255 // if this argument is passed by val
256 if (call_attribs.hasAttribute(i, llvm::Attribute::ByVal)) {
257 // strip away the byval attribute
258 call_inst->removeAttribute(i, llvm::Attribute::ByVal);
264 llvm::AttributeSet attr_byval =
265 llvm::AttributeSet::get(module.getContext(), 1u, llvm::Attribute::ByVal);
267 // for all called function decls
268 for (auto func : rs_functions) {
269 // inspect all of the arguments in the call
270 llvm::SymbolTableList<llvm::Argument> &arg_list = func->getArgumentList();
271 for (auto &arg : arg_list) {
272 if (arg.hasByValAttr()) {
273 arg.removeAttr(attr_byval);
280 } // end anonymous namespace
282 namespace lldb_private {
283 namespace lldb_renderscript {
285 bool fixupX86FunctionCalls(llvm::Module &module) {
286 return fixupX86StructRetCalls(module);
289 bool fixupX86_64FunctionCalls(llvm::Module &module) {
290 bool changed = false;
291 changed |= fixupX86StructRetCalls(module);
292 changed |= fixupRSAllocationStructByValCalls(module);
296 } // end namespace lldb_renderscript
297 } // end namespace lldb_private