1 files changed, 297 insertions, 0 deletions
diff --git a/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp b/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp
new file mode 100644
index 000000000000..ba531b2e3f2d
--- /dev/null
+++ b/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptx86ABIFixups.cpp
@@ -0,0 +1,297 @@
+//===-- RenderScriptx86ABIFixups.cpp ----------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// C Includes
+// C++ Includes
+#include <set>
+
+// Other libraries and framework includes
+#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IRReader/IRReader.h"
+#include "llvm/Pass.h"
+
+// Project includes
+#include "lldb/Core/Log.h"
+#include "lldb/Target/Process.h"
+
+using namespace lldb_private;
+namespace {
+
+bool isRSAPICall(llvm::Module &module, llvm::CallInst *call_inst) {
+  // TODO get the list of renderscript modules from lldb and check if
+  // this llvm::Module calls into any of them.
+  (void)module;
+  const auto func_name = call_inst->getCalledFunction()->getName();
+  if (func_name.startswith("llvm") || func_name.startswith("lldb"))
+    return false;
+
+  if (call_inst->getCalledFunction()->isIntrinsic())
+    return false;
+
+  return true;
+}
+
+bool isRSLargeReturnCall(llvm::Module &module, llvm::CallInst *call_inst) {
+  // i686 and x86_64 returns for large vectors in the RenderScript API are not
+  // handled as normal
+  // register pairs, but as a hidden sret type. This is not reflected in the
+  // debug info or mangled
+  // symbol name, and the android ABI for x86 and x86_64, (as well as the
+  // emulators) specifies there is
+  // no AVX, so bcc generates an sret function because we cannot natively return
+  // 256 bit vectors.
+  // This function simply checks whether a function has a > 128bit return type.
+  // It is perhaps an
+  // unreliable heuristic, and relies on bcc not generating AVX code, so if the
+  // android ABI one day
+  // provides for AVX, this function may go out of fashion.
+  (void)module;
+  if (!call_inst || !call_inst->getCalledFunction())
+    return false;
+
+  return call_inst->getCalledFunction()
+             ->getReturnType()
+             ->getPrimitiveSizeInBits() > 128;
+}
+
+bool isRSAllocationPtrTy(const llvm::Type *type) {
+  if (!type->isPointerTy())
+    return false;
+  auto ptr_type = type->getPointerElementType();
+
+  return ptr_type->isStructTy() &&
+         ptr_type->getStructName().startswith("struct.rs_allocation");
+}
+
+bool isRSAllocationTyCallSite(llvm::Module &module, llvm::CallInst *call_inst) {
+  (void)module;
+  if (!call_inst->hasByValArgument())
+    return false;
+  for (const auto &param : call_inst->operand_values())
+    if (isRSAllocationPtrTy(param->getType()))
+      return true;
+  return false;
+}
+
+llvm::FunctionType *cloneToStructRetFnTy(llvm::CallInst *call_inst) {
+  // on x86 StructReturn functions return a pointer to the return value, rather
+  // than the return
+  // value itself [ref](http://www.agner.org/optimize/calling_conventions.pdf
+  // section 6).
+  // We create a return type by getting the pointer type of the old return type,
+  // and inserting a new
+  // initial argument of pointer type of the original return type.
+  Log *log(
+      GetLogIfAnyCategoriesSet(LIBLLDB_LOG_LANGUAGE | LIBLLDB_LOG_EXPRESSIONS));
+
+  assert(call_inst && "no CallInst");
+  llvm::Function *orig = call_inst->getCalledFunction();
+  assert(orig && "CallInst has no called function");
+  llvm::FunctionType *orig_type = orig->getFunctionType();
+  auto name = orig->getName();
+  if (log)
+    log->Printf("%s - cloning to StructRet function for '%s'", __FUNCTION__,
+                name.str().c_str());
+
+  unsigned num_params = orig_type->getNumParams();
+  std::vector<llvm::Type *> new_params{num_params + 1, nullptr};
+  std::vector<llvm::Type *> params{orig_type->param_begin(),
+                                   orig_type->param_end()};
+
+  // This may not work if the function is somehow declared void as llvm is
+  // strongly typed
+  // and represents void* with i8*
+  assert(!orig_type->getReturnType()->isVoidTy() &&
+         "Cannot add StructRet attribute to void function");
+  llvm::PointerType *return_type_ptr_type =
+      llvm::PointerType::getUnqual(orig->getReturnType());
+  assert(return_type_ptr_type &&
+         "failed to get function return type PointerType");
+  if (!return_type_ptr_type)
+    return nullptr;
+
+  if (log)
+    log->Printf("%s - return type pointer type for StructRet clone @ '0x%p':\n",
+                __FUNCTION__, (void *)return_type_ptr_type);
+  // put the the sret pointer argument in place at the beginning of the argument
+  // list.
+  params.emplace(params.begin(), return_type_ptr_type);
+  assert(params.size() == num_params + 1);
+  return llvm::FunctionType::get(return_type_ptr_type, params,
+                                 orig->isVarArg());
+}
+
+bool findRSCallSites(llvm::Module &module,
+                     std::set<llvm::CallInst *> &rs_callsites,
+                     bool (*predicate)(llvm::Module &, llvm::CallInst *)) {
+  bool found = false;
+
+  for (auto &func : module.getFunctionList())
+    for (auto &block : func.getBasicBlockList())
+      for (auto &inst : block) {
+        llvm::CallInst *call_inst =
+            llvm::dyn_cast_or_null<llvm::CallInst>(&inst);
+        if (!call_inst || !call_inst->getCalledFunction())
+          // This is not the call-site you are looking for...
+          continue;
+        if (isRSAPICall(module, call_inst) && predicate(module, call_inst)) {
+          rs_callsites.insert(call_inst);
+          found = true;
+        }
+      }
+  return found;
+}
+
+bool fixupX86StructRetCalls(llvm::Module &module) {
+  bool changed = false;
+  // changing a basic block while iterating over it seems to have some undefined
+  // behaviour
+  // going on so we find all RS callsites first, then fix them up after
+  // consuming
+  // the iterator.
+  std::set<llvm::CallInst *> rs_callsites;
+  if (!findRSCallSites(module, rs_callsites, isRSLargeReturnCall))
+    return false;
+
+  for (auto call_inst : rs_callsites) {
+    llvm::FunctionType *new_func_type = cloneToStructRetFnTy(call_inst);
+    assert(new_func_type &&
+           "failed to clone functionType for Renderscript ABI fixup");
+
+    llvm::CallSite call_site(call_inst);
+    llvm::Function *func = call_inst->getCalledFunction();
+    assert(func && "cannot resolve function in RenderScriptRuntime");
+    // Copy the original call arguments
+    std::vector<llvm::Value *> new_call_args(call_site.arg_begin(),
+                                             call_site.arg_end());
+
+    // Allocate enough space to store the return value of the original function
+    // we pass a pointer to this allocation as the StructRet param, and then
+    // copy its
+    // value into the lldb return value
+    llvm::AllocaInst *return_value_alloc = new llvm::AllocaInst(
+        func->getReturnType(), "var_vector_return_alloc", call_inst);
+    // use the new allocation as the new first argument
+    new_call_args.emplace(new_call_args.begin(),
+                          llvm::cast<llvm::Value>(return_value_alloc));
+    llvm::PointerType *new_func_ptr_type =
+        llvm::PointerType::get(new_func_type, 0);
+    // Create the type cast from the old function type to the new one
+    llvm::Constant *new_func_cast = llvm::ConstantExpr::getCast(
+        llvm::Instruction::BitCast, func, new_func_ptr_type);
+    // create an allocation for a new function pointer
+    llvm::AllocaInst *new_func_ptr =
+        new llvm::AllocaInst(new_func_ptr_type, "new_func_ptr", call_inst);
+    // store the new_func_cast to the newly allocated space
+    (void)new llvm::StoreInst(new_func_cast, new_func_ptr,
+                              "new_func_ptr_load_cast", call_inst);
+    // load the new function address ready for a jump
+    llvm::LoadInst *new_func_addr_load =
+        new llvm::LoadInst(new_func_ptr, "load_func_pointer", call_inst);
+    // and create a callinstruction from it
+    llvm::CallInst *new_call_inst = llvm::CallInst::Create(
+        new_func_addr_load, new_call_args, "new_func_call", call_inst);
+    new_call_inst->setCallingConv(call_inst->getCallingConv());
+    new_call_inst->setTailCall(call_inst->isTailCall());
+    llvm::LoadInst *lldb_save_result_address =
+        new llvm::LoadInst(return_value_alloc, "save_return_val", call_inst);
+
+    // Now remove the old broken call
+    call_inst->replaceAllUsesWith(lldb_save_result_address);
+    call_inst->eraseFromParent();
+    changed = true;
+  }
+  return changed;
+}
+
+bool fixupRSAllocationStructByValCalls(llvm::Module &module) {
+  // On x86_64, calls to functions in the RS runtime that take an
+  // `rs_allocation` type argument
+  // are actually handled as by-ref params by bcc, but appear to be passed by
+  // value by lldb (the callsite all use
+  // `struct byval`).
+  // On x86_64 Linux, struct arguments are transferred in registers if the
+  // struct size is no bigger than
+  // 128bits [ref](http://www.agner.org/optimize/calling_conventions.pdf)
+  // section 7.1 "Passing and returning objects"
+  // otherwise passed on the stack.
+  // an object of type `rs_allocation` is actually 256bits, so should be passed
+  // on the stack. However, code generated
+  // by bcc actually treats formal params of type `rs_allocation` as
+  // `rs_allocation *` so we need to convert the
+  // calling convention to pass by reference, and remove any hint of byval from
+  // formal parameters.
+  bool changed = false;
+  std::set<llvm::CallInst *> rs_callsites;
+  if (!findRSCallSites(module, rs_callsites, isRSAllocationTyCallSite))
+    return false;
+
+  std::set<llvm::Function *> rs_functions;
+
+  // for all call instructions
+  for (auto call_inst : rs_callsites) {
+    // add the called function to a set so that we can strip its byval
+    // attributes in another pass
+    rs_functions.insert(call_inst->getCalledFunction());
+
+    // get the function attributes
+    llvm::AttributeSet call_attribs = call_inst->getAttributes();
+
+    // iterate over the argument attributes
+    for (size_t i = 1; i <= call_attribs.getNumSlots(); ++i) {
+      // if this argument is passed by val
+      if (call_attribs.hasAttribute(i, llvm::Attribute::ByVal)) {
+        // strip away the byval attribute
+        call_inst->removeAttribute(i, llvm::Attribute::ByVal);
+        changed = true;
+      }
+    }
+  }
+
+  llvm::AttributeSet attr_byval =
+      llvm::AttributeSet::get(module.getContext(), 1u, llvm::Attribute::ByVal);
+
+  // for all called function decls
+  for (auto func : rs_functions) {
+    // inspect all of the arguments in the call
+    llvm::SymbolTableList<llvm::Argument> &arg_list = func->getArgumentList();
+    for (auto &arg : arg_list) {
+      if (arg.hasByValAttr()) {
+        arg.removeAttr(attr_byval);
+        changed = true;
+      }
+    }
+  }
+  return changed;
+}
+} // end anonymous namespace
+
+namespace lldb_private {
+namespace lldb_renderscript {
+
+bool fixupX86FunctionCalls(llvm::Module &module) {
+  return fixupX86StructRetCalls(module);
+}
+
+bool fixupX86_64FunctionCalls(llvm::Module &module) {
+  bool changed = false;
+  changed |= fixupX86StructRetCalls(module);
+  changed |= fixupRSAllocationStructByValCalls(module);
+  return changed;
+}
+
+} // end namespace lldb_renderscript
+} // end namespace lldb_private