1 //===-- IRInterpreter.cpp ---------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lldb/Expression/IRInterpreter.h"
11 #include "lldb/Core/ConstString.h"
12 #include "lldb/Core/DataExtractor.h"
13 #include "lldb/Core/Error.h"
14 #include "lldb/Core/Log.h"
15 #include "lldb/Core/Module.h"
16 #include "lldb/Core/ModuleSpec.h"
17 #include "lldb/Core/Scalar.h"
18 #include "lldb/Core/StreamString.h"
19 #include "lldb/Core/ValueObject.h"
20 #include "lldb/Expression/DiagnosticManager.h"
21 #include "lldb/Expression/IRExecutionUnit.h"
22 #include "lldb/Expression/IRMemoryMap.h"
23 #include "lldb/Host/Endian.h"
24 
25 #include "lldb/Target/ABI.h"
26 #include "lldb/Target/ExecutionContext.h"
27 #include "lldb/Target/Target.h"
28 #include "lldb/Target/Thread.h"
29 #include "lldb/Target/ThreadPlan.h"
30 #include "lldb/Target/ThreadPlanCallFunctionUsingABI.h"
31 
32 #include "llvm/IR/Constants.h"
33 #include "llvm/IR/DataLayout.h"
34 #include "llvm/IR/Function.h"
35 #include "llvm/IR/Instructions.h"
36 #include "llvm/IR/Intrinsics.h"
37 #include "llvm/IR/LLVMContext.h"
38 #include "llvm/IR/Module.h"
39 #include "llvm/IR/Operator.h"
40 #include "llvm/Support/raw_ostream.h"
41 
42 #include <map>
43 
44 using namespace llvm;
45 
46 static std::string PrintValue(const Value *value, bool truncate = false) {
47   std::string s;
48   raw_string_ostream rso(s);
49   value->print(rso);
50   rso.flush();
51   if (truncate)
52     s.resize(s.length() - 1);
53 
54   size_t offset;
55   while ((offset = s.find('\n')) != s.npos)
56     s.erase(offset, 1);
57   while (s[0] == ' ' || s[0] == '\t')
58     s.erase(0, 1);
59 
60   return s;
61 }
62 
63 static std::string PrintType(const Type *type, bool truncate = false) {
64   std::string s;
65   raw_string_ostream rso(s);
66   type->print(rso);
67   rso.flush();
68   if (truncate)
69     s.resize(s.length() - 1);
70   return s;
71 }
72 
73 static bool CanIgnoreCall(const CallInst *call) {
74   const llvm::Function *called_function = call->getCalledFunction();
75 
76   if (!called_function)
77     return false;
78 
79   if (called_function->isIntrinsic()) {
80     switch (called_function->getIntrinsicID()) {
81     default:
82       break;
83     case llvm::Intrinsic::dbg_declare:
84     case llvm::Intrinsic::dbg_value:
85       return true;
86     }
87   }
88 
89   return false;
90 }
91 
92 class InterpreterStackFrame {
93 public:
94   typedef std::map<const Value *, lldb::addr_t> ValueMap;
95 
96   ValueMap m_values;
97   DataLayout &m_target_data;
98   lldb_private::IRExecutionUnit &m_execution_unit;
99   const BasicBlock *m_bb;
100   const BasicBlock *m_prev_bb;
101   BasicBlock::const_iterator m_ii;
102   BasicBlock::const_iterator m_ie;
103 
104   lldb::addr_t m_frame_process_address;
105   size_t m_frame_size;
106   lldb::addr_t m_stack_pointer;
107 
108   lldb::ByteOrder m_byte_order;
109   size_t m_addr_byte_size;
110 
111   InterpreterStackFrame(DataLayout &target_data,
112                         lldb_private::IRExecutionUnit &execution_unit,
113                         lldb::addr_t stack_frame_bottom,
114                         lldb::addr_t stack_frame_top)
115       : m_target_data(target_data), m_execution_unit(execution_unit),
116         m_bb(nullptr), m_prev_bb(nullptr) {
117     m_byte_order = (target_data.isLittleEndian() ? lldb::eByteOrderLittle
118                                                  : lldb::eByteOrderBig);
119     m_addr_byte_size = (target_data.getPointerSize(0));
120 
121     m_frame_process_address = stack_frame_bottom;
122     m_frame_size = stack_frame_top - stack_frame_bottom;
123     m_stack_pointer = stack_frame_top;
124   }
125 
126   ~InterpreterStackFrame() {}
127 
128   void Jump(const BasicBlock *bb) {
129     m_prev_bb = m_bb;
130     m_bb = bb;
131     m_ii = m_bb->begin();
132     m_ie = m_bb->end();
133   }
134 
135   std::string SummarizeValue(const Value *value) {
136     lldb_private::StreamString ss;
137 
138     ss.Printf("%s", PrintValue(value).c_str());
139 
140     ValueMap::iterator i = m_values.find(value);
141 
142     if (i != m_values.end()) {
143       lldb::addr_t addr = i->second;
144 
145       ss.Printf(" 0x%llx", (unsigned long long)addr);
146     }
147 
148     return ss.GetString();
149   }
150 
151   bool AssignToMatchType(lldb_private::Scalar &scalar, uint64_t u64value,
152                          Type *type) {
153     size_t type_size = m_target_data.getTypeStoreSize(type);
154 
155     switch (type_size) {
156     case 1:
157       scalar = (uint8_t)u64value;
158       break;
159     case 2:
160       scalar = (uint16_t)u64value;
161       break;
162     case 4:
163       scalar = (uint32_t)u64value;
164       break;
165     case 8:
166       scalar = (uint64_t)u64value;
167       break;
168     default:
169       return false;
170     }
171 
172     return true;
173   }
174 
175   bool EvaluateValue(lldb_private::Scalar &scalar, const Value *value,
176                      Module &module) {
177     const Constant *constant = dyn_cast<Constant>(value);
178 
179     if (constant) {
180       APInt value_apint;
181 
182       if (!ResolveConstantValue(value_apint, constant))
183         return false;
184 
185       return AssignToMatchType(scalar, value_apint.getLimitedValue(),
186                                value->getType());
187     } else {
188       lldb::addr_t process_address = ResolveValue(value, module);
189       size_t value_size = m_target_data.getTypeStoreSize(value->getType());
190 
191       lldb_private::DataExtractor value_extractor;
192       lldb_private::Error extract_error;
193 
194       m_execution_unit.GetMemoryData(value_extractor, process_address,
195                                      value_size, extract_error);
196 
197       if (!extract_error.Success())
198         return false;
199 
200       lldb::offset_t offset = 0;
201       if (value_size == 1 || value_size == 2 || value_size == 4 ||
202           value_size == 8) {
203         uint64_t u64value = value_extractor.GetMaxU64(&offset, value_size);
204         return AssignToMatchType(scalar, u64value, value->getType());
205       }
206     }
207 
208     return false;
209   }
210 
211   bool AssignValue(const Value *value, lldb_private::Scalar &scalar,
212                    Module &module) {
213     lldb::addr_t process_address = ResolveValue(value, module);
214 
215     if (process_address == LLDB_INVALID_ADDRESS)
216       return false;
217 
218     lldb_private::Scalar cast_scalar;
219 
220     if (!AssignToMatchType(cast_scalar, scalar.ULongLong(), value->getType()))
221       return false;
222 
223     size_t value_byte_size = m_target_data.getTypeStoreSize(value->getType());
224 
225     lldb_private::DataBufferHeap buf(value_byte_size, 0);
226 
227     lldb_private::Error get_data_error;
228 
229     if (!cast_scalar.GetAsMemoryData(buf.GetBytes(), buf.GetByteSize(),
230                                      m_byte_order, get_data_error))
231       return false;
232 
233     lldb_private::Error write_error;
234 
235     m_execution_unit.WriteMemory(process_address, buf.GetBytes(),
236                                  buf.GetByteSize(), write_error);
237 
238     return write_error.Success();
239   }
240 
241   bool ResolveConstantValue(APInt &value, const Constant *constant) {
242     switch (constant->getValueID()) {
243     default:
244       break;
245     case Value::FunctionVal:
246       if (const Function *constant_func = dyn_cast<Function>(constant)) {
247         lldb_private::ConstString name(constant_func->getName());
248         lldb::addr_t addr = m_execution_unit.FindSymbol(name);
249         if (addr == LLDB_INVALID_ADDRESS)
250           return false;
251         value = APInt(m_target_data.getPointerSizeInBits(), addr);
252         return true;
253       }
254       break;
255     case Value::ConstantIntVal:
256       if (const ConstantInt *constant_int = dyn_cast<ConstantInt>(constant)) {
257         value = constant_int->getValue();
258         return true;
259       }
260       break;
261     case Value::ConstantFPVal:
262       if (const ConstantFP *constant_fp = dyn_cast<ConstantFP>(constant)) {
263         value = constant_fp->getValueAPF().bitcastToAPInt();
264         return true;
265       }
266       break;
267     case Value::ConstantExprVal:
268       if (const ConstantExpr *constant_expr =
269               dyn_cast<ConstantExpr>(constant)) {
270         switch (constant_expr->getOpcode()) {
271         default:
272           return false;
273         case Instruction::IntToPtr:
274         case Instruction::PtrToInt:
275         case Instruction::BitCast:
276           return ResolveConstantValue(value, constant_expr->getOperand(0));
277         case Instruction::GetElementPtr: {
278           ConstantExpr::const_op_iterator op_cursor = constant_expr->op_begin();
279           ConstantExpr::const_op_iterator op_end = constant_expr->op_end();
280 
281           Constant *base = dyn_cast<Constant>(*op_cursor);
282 
283           if (!base)
284             return false;
285 
286           if (!ResolveConstantValue(value, base))
287             return false;
288 
289           op_cursor++;
290 
291           if (op_cursor == op_end)
292             return true; // no offset to apply!
293 
294           SmallVector<Value *, 8> indices(op_cursor, op_end);
295 
296           Type *src_elem_ty =
297               cast<GEPOperator>(constant_expr)->getSourceElementType();
298           uint64_t offset =
299               m_target_data.getIndexedOffsetInType(src_elem_ty, indices);
300 
301           const bool is_signed = true;
302           value += APInt(value.getBitWidth(), offset, is_signed);
303 
304           return true;
305         }
306         }
307       }
308       break;
309     case Value::ConstantPointerNullVal:
310       if (isa<ConstantPointerNull>(constant)) {
311         value = APInt(m_target_data.getPointerSizeInBits(), 0);
312         return true;
313       }
314       break;
315     }
316     return false;
317   }
318 
319   bool MakeArgument(const Argument *value, uint64_t address) {
320     lldb::addr_t data_address = Malloc(value->getType());
321 
322     if (data_address == LLDB_INVALID_ADDRESS)
323       return false;
324 
325     lldb_private::Error write_error;
326 
327     m_execution_unit.WritePointerToMemory(data_address, address, write_error);
328 
329     if (!write_error.Success()) {
330       lldb_private::Error free_error;
331       m_execution_unit.Free(data_address, free_error);
332       return false;
333     }
334 
335     m_values[value] = data_address;
336 
337     lldb_private::Log *log(
338         lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
339 
340     if (log) {
341       log->Printf("Made an allocation for argument %s",
342                   PrintValue(value).c_str());
343       log->Printf("  Data region    : %llx", (unsigned long long)address);
344       log->Printf("  Ref region     : %llx", (unsigned long long)data_address);
345     }
346 
347     return true;
348   }
349 
350   bool ResolveConstant(lldb::addr_t process_address, const Constant *constant) {
351     APInt resolved_value;
352 
353     if (!ResolveConstantValue(resolved_value, constant))
354       return false;
355 
356     size_t constant_size = m_target_data.getTypeStoreSize(constant->getType());
357     lldb_private::DataBufferHeap buf(constant_size, 0);
358 
359     lldb_private::Error get_data_error;
360 
361     lldb_private::Scalar resolved_scalar(
362         resolved_value.zextOrTrunc(llvm::NextPowerOf2(constant_size) * 8));
363     if (!resolved_scalar.GetAsMemoryData(buf.GetBytes(), buf.GetByteSize(),
364                                          m_byte_order, get_data_error))
365       return false;
366 
367     lldb_private::Error write_error;
368 
369     m_execution_unit.WriteMemory(process_address, buf.GetBytes(),
370                                  buf.GetByteSize(), write_error);
371 
372     return write_error.Success();
373   }
374 
375   lldb::addr_t Malloc(size_t size, uint8_t byte_alignment) {
376     lldb::addr_t ret = m_stack_pointer;
377 
378     ret -= size;
379     ret -= (ret % byte_alignment);
380 
381     if (ret < m_frame_process_address)
382       return LLDB_INVALID_ADDRESS;
383 
384     m_stack_pointer = ret;
385     return ret;
386   }
387 
388   lldb::addr_t MallocPointer() {
389     return Malloc(m_target_data.getPointerSize(),
390                   m_target_data.getPointerPrefAlignment());
391   }
392 
393   lldb::addr_t Malloc(llvm::Type *type) {
394     lldb_private::Error alloc_error;
395 
396     return Malloc(m_target_data.getTypeAllocSize(type),
397                   m_target_data.getPrefTypeAlignment(type));
398   }
399 
400   std::string PrintData(lldb::addr_t addr, llvm::Type *type) {
401     size_t length = m_target_data.getTypeStoreSize(type);
402 
403     lldb_private::DataBufferHeap buf(length, 0);
404 
405     lldb_private::Error read_error;
406 
407     m_execution_unit.ReadMemory(buf.GetBytes(), addr, length, read_error);
408 
409     if (!read_error.Success())
410       return std::string("<couldn't read data>");
411 
412     lldb_private::StreamString ss;
413 
414     for (size_t i = 0; i < length; i++) {
415       if ((!(i & 0xf)) && i)
416         ss.Printf("%02hhx - ", buf.GetBytes()[i]);
417       else
418         ss.Printf("%02hhx ", buf.GetBytes()[i]);
419     }
420 
421     return ss.GetString();
422   }
423 
424   lldb::addr_t ResolveValue(const Value *value, Module &module) {
425     ValueMap::iterator i = m_values.find(value);
426 
427     if (i != m_values.end())
428       return i->second;
429 
430     // Fall back and allocate space [allocation type Alloca]
431 
432     lldb::addr_t data_address = Malloc(value->getType());
433 
434     if (const Constant *constant = dyn_cast<Constant>(value)) {
435       if (!ResolveConstant(data_address, constant)) {
436         lldb_private::Error free_error;
437         m_execution_unit.Free(data_address, free_error);
438         return LLDB_INVALID_ADDRESS;
439       }
440     }
441 
442     m_values[value] = data_address;
443     return data_address;
444   }
445 };
446 
447 static const char *unsupported_opcode_error =
448     "Interpreter doesn't handle one of the expression's opcodes";
449 static const char *unsupported_operand_error =
450     "Interpreter doesn't handle one of the expression's operands";
451 // static const char *interpreter_initialization_error = "Interpreter couldn't
452 // be initialized";
453 static const char *interpreter_internal_error =
454     "Interpreter encountered an internal error";
455 static const char *bad_value_error =
456     "Interpreter couldn't resolve a value during execution";
457 static const char *memory_allocation_error =
458     "Interpreter couldn't allocate memory";
459 static const char *memory_write_error = "Interpreter couldn't write to memory";
460 static const char *memory_read_error = "Interpreter couldn't read from memory";
461 static const char *infinite_loop_error = "Interpreter ran for too many cycles";
462 // static const char *bad_result_error                 = "Result of expression
463 // is in bad memory";
464 static const char *too_many_functions_error =
465     "Interpreter doesn't handle modules with multiple function bodies.";
466 
467 static bool CanResolveConstant(llvm::Constant *constant) {
468   switch (constant->getValueID()) {
469   default:
470     return false;
471   case Value::ConstantIntVal:
472   case Value::ConstantFPVal:
473   case Value::FunctionVal:
474     return true;
475   case Value::ConstantExprVal:
476     if (const ConstantExpr *constant_expr = dyn_cast<ConstantExpr>(constant)) {
477       switch (constant_expr->getOpcode()) {
478       default:
479         return false;
480       case Instruction::IntToPtr:
481       case Instruction::PtrToInt:
482       case Instruction::BitCast:
483         return CanResolveConstant(constant_expr->getOperand(0));
484       case Instruction::GetElementPtr: {
485         ConstantExpr::const_op_iterator op_cursor = constant_expr->op_begin();
486         Constant *base = dyn_cast<Constant>(*op_cursor);
487         if (!base)
488           return false;
489 
490         return CanResolveConstant(base);
491       }
492       }
493     } else {
494       return false;
495     }
496   case Value::ConstantPointerNullVal:
497     return true;
498   }
499 }
500 
501 bool IRInterpreter::CanInterpret(llvm::Module &module, llvm::Function &function,
502                                  lldb_private::Error &error,
503                                  const bool support_function_calls) {
504   lldb_private::Log *log(
505       lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
506 
507   bool saw_function_with_body = false;
508 
509   for (Module::iterator fi = module.begin(), fe = module.end(); fi != fe;
510        ++fi) {
511     if (fi->begin() != fi->end()) {
512       if (saw_function_with_body) {
513         if (log)
514           log->Printf("More than one function in the module has a body");
515         error.SetErrorToGenericError();
516         error.SetErrorString(too_many_functions_error);
517         return false;
518       }
519       saw_function_with_body = true;
520     }
521   }
522 
523   for (Function::iterator bbi = function.begin(), bbe = function.end();
524        bbi != bbe; ++bbi) {
525     for (BasicBlock::iterator ii = bbi->begin(), ie = bbi->end(); ii != ie;
526          ++ii) {
527       switch (ii->getOpcode()) {
528       default: {
529         if (log)
530           log->Printf("Unsupported instruction: %s", PrintValue(&*ii).c_str());
531         error.SetErrorToGenericError();
532         error.SetErrorString(unsupported_opcode_error);
533         return false;
534       }
535       case Instruction::Add:
536       case Instruction::Alloca:
537       case Instruction::BitCast:
538       case Instruction::Br:
539       case Instruction::PHI:
540         break;
541       case Instruction::Call: {
542         CallInst *call_inst = dyn_cast<CallInst>(ii);
543 
544         if (!call_inst) {
545           error.SetErrorToGenericError();
546           error.SetErrorString(interpreter_internal_error);
547           return false;
548         }
549 
550         if (!CanIgnoreCall(call_inst) && !support_function_calls) {
551           if (log)
552             log->Printf("Unsupported instruction: %s",
553                         PrintValue(&*ii).c_str());
554           error.SetErrorToGenericError();
555           error.SetErrorString(unsupported_opcode_error);
556           return false;
557         }
558       } break;
559       case Instruction::GetElementPtr:
560         break;
561       case Instruction::ICmp: {
562         ICmpInst *icmp_inst = dyn_cast<ICmpInst>(ii);
563 
564         if (!icmp_inst) {
565           error.SetErrorToGenericError();
566           error.SetErrorString(interpreter_internal_error);
567           return false;
568         }
569 
570         switch (icmp_inst->getPredicate()) {
571         default: {
572           if (log)
573             log->Printf("Unsupported ICmp predicate: %s",
574                         PrintValue(&*ii).c_str());
575 
576           error.SetErrorToGenericError();
577           error.SetErrorString(unsupported_opcode_error);
578           return false;
579         }
580         case CmpInst::ICMP_EQ:
581         case CmpInst::ICMP_NE:
582         case CmpInst::ICMP_UGT:
583         case CmpInst::ICMP_UGE:
584         case CmpInst::ICMP_ULT:
585         case CmpInst::ICMP_ULE:
586         case CmpInst::ICMP_SGT:
587         case CmpInst::ICMP_SGE:
588         case CmpInst::ICMP_SLT:
589         case CmpInst::ICMP_SLE:
590           break;
591         }
592       } break;
593       case Instruction::And:
594       case Instruction::AShr:
595       case Instruction::IntToPtr:
596       case Instruction::PtrToInt:
597       case Instruction::Load:
598       case Instruction::LShr:
599       case Instruction::Mul:
600       case Instruction::Or:
601       case Instruction::Ret:
602       case Instruction::SDiv:
603       case Instruction::SExt:
604       case Instruction::Shl:
605       case Instruction::SRem:
606       case Instruction::Store:
607       case Instruction::Sub:
608       case Instruction::Trunc:
609       case Instruction::UDiv:
610       case Instruction::URem:
611       case Instruction::Xor:
612       case Instruction::ZExt:
613         break;
614       }
615 
616       for (int oi = 0, oe = ii->getNumOperands(); oi != oe; ++oi) {
617         Value *operand = ii->getOperand(oi);
618         Type *operand_type = operand->getType();
619 
620         switch (operand_type->getTypeID()) {
621         default:
622           break;
623         case Type::VectorTyID: {
624           if (log)
625             log->Printf("Unsupported operand type: %s",
626                         PrintType(operand_type).c_str());
627           error.SetErrorString(unsupported_operand_error);
628           return false;
629         }
630         }
631 
632         if (Constant *constant = llvm::dyn_cast<Constant>(operand)) {
633           if (!CanResolveConstant(constant)) {
634             if (log)
635               log->Printf("Unsupported constant: %s",
636                           PrintValue(constant).c_str());
637             error.SetErrorString(unsupported_operand_error);
638             return false;
639           }
640         }
641       }
642     }
643   }
644 
645   return true;
646 }
647 
648 bool IRInterpreter::Interpret(llvm::Module &module, llvm::Function &function,
649                               llvm::ArrayRef<lldb::addr_t> args,
650                               lldb_private::IRExecutionUnit &execution_unit,
651                               lldb_private::Error &error,
652                               lldb::addr_t stack_frame_bottom,
653                               lldb::addr_t stack_frame_top,
654                               lldb_private::ExecutionContext &exe_ctx) {
655   lldb_private::Log *log(
656       lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
657 
658   if (log) {
659     std::string s;
660     raw_string_ostream oss(s);
661 
662     module.print(oss, NULL);
663 
664     oss.flush();
665 
666     log->Printf("Module as passed in to IRInterpreter::Interpret: \n\"%s\"",
667                 s.c_str());
668   }
669 
670   DataLayout data_layout(&module);
671 
672   InterpreterStackFrame frame(data_layout, execution_unit, stack_frame_bottom,
673                               stack_frame_top);
674 
675   if (frame.m_frame_process_address == LLDB_INVALID_ADDRESS) {
676     error.SetErrorString("Couldn't allocate stack frame");
677   }
678 
679   int arg_index = 0;
680 
681   for (llvm::Function::arg_iterator ai = function.arg_begin(),
682                                     ae = function.arg_end();
683        ai != ae; ++ai, ++arg_index) {
684     if (args.size() <= static_cast<size_t>(arg_index)) {
685       error.SetErrorString("Not enough arguments passed in to function");
686       return false;
687     }
688 
689     lldb::addr_t ptr = args[arg_index];
690 
691     frame.MakeArgument(&*ai, ptr);
692   }
693 
694   uint32_t num_insts = 0;
695 
696   frame.Jump(&function.front());
697 
698   while (frame.m_ii != frame.m_ie && (++num_insts < 4096)) {
699     const Instruction *inst = &*frame.m_ii;
700 
701     if (log)
702       log->Printf("Interpreting %s", PrintValue(inst).c_str());
703 
704     switch (inst->getOpcode()) {
705     default:
706       break;
707 
708     case Instruction::Add:
709     case Instruction::Sub:
710     case Instruction::Mul:
711     case Instruction::SDiv:
712     case Instruction::UDiv:
713     case Instruction::SRem:
714     case Instruction::URem:
715     case Instruction::Shl:
716     case Instruction::LShr:
717     case Instruction::AShr:
718     case Instruction::And:
719     case Instruction::Or:
720     case Instruction::Xor: {
721       const BinaryOperator *bin_op = dyn_cast<BinaryOperator>(inst);
722 
723       if (!bin_op) {
724         if (log)
725           log->Printf(
726               "getOpcode() returns %s, but instruction is not a BinaryOperator",
727               inst->getOpcodeName());
728         error.SetErrorToGenericError();
729         error.SetErrorString(interpreter_internal_error);
730         return false;
731       }
732 
733       Value *lhs = inst->getOperand(0);
734       Value *rhs = inst->getOperand(1);
735 
736       lldb_private::Scalar L;
737       lldb_private::Scalar R;
738 
739       if (!frame.EvaluateValue(L, lhs, module)) {
740         if (log)
741           log->Printf("Couldn't evaluate %s", PrintValue(lhs).c_str());
742         error.SetErrorToGenericError();
743         error.SetErrorString(bad_value_error);
744         return false;
745       }
746 
747       if (!frame.EvaluateValue(R, rhs, module)) {
748         if (log)
749           log->Printf("Couldn't evaluate %s", PrintValue(rhs).c_str());
750         error.SetErrorToGenericError();
751         error.SetErrorString(bad_value_error);
752         return false;
753       }
754 
755       lldb_private::Scalar result;
756 
757       switch (inst->getOpcode()) {
758       default:
759         break;
760       case Instruction::Add:
761         result = L + R;
762         break;
763       case Instruction::Mul:
764         result = L * R;
765         break;
766       case Instruction::Sub:
767         result = L - R;
768         break;
769       case Instruction::SDiv:
770         L.MakeSigned();
771         R.MakeSigned();
772         result = L / R;
773         break;
774       case Instruction::UDiv:
775         L.MakeUnsigned();
776         R.MakeUnsigned();
777         result = L / R;
778         break;
779       case Instruction::SRem:
780         L.MakeSigned();
781         R.MakeSigned();
782         result = L % R;
783         break;
784       case Instruction::URem:
785         L.MakeUnsigned();
786         R.MakeUnsigned();
787         result = L % R;
788         break;
789       case Instruction::Shl:
790         result = L << R;
791         break;
792       case Instruction::AShr:
793         result = L >> R;
794         break;
795       case Instruction::LShr:
796         result = L;
797         result.ShiftRightLogical(R);
798         break;
799       case Instruction::And:
800         result = L & R;
801         break;
802       case Instruction::Or:
803         result = L | R;
804         break;
805       case Instruction::Xor:
806         result = L ^ R;
807         break;
808       }
809 
810       frame.AssignValue(inst, result, module);
811 
812       if (log) {
813         log->Printf("Interpreted a %s", inst->getOpcodeName());
814         log->Printf("  L : %s", frame.SummarizeValue(lhs).c_str());
815         log->Printf("  R : %s", frame.SummarizeValue(rhs).c_str());
816         log->Printf("  = : %s", frame.SummarizeValue(inst).c_str());
817       }
818     } break;
819     case Instruction::Alloca: {
820       const AllocaInst *alloca_inst = dyn_cast<AllocaInst>(inst);
821 
822       if (!alloca_inst) {
823         if (log)
824           log->Printf("getOpcode() returns Alloca, but instruction is not an "
825                       "AllocaInst");
826         error.SetErrorToGenericError();
827         error.SetErrorString(interpreter_internal_error);
828         return false;
829       }
830 
831       if (alloca_inst->isArrayAllocation()) {
832         if (log)
833           log->Printf(
834               "AllocaInsts are not handled if isArrayAllocation() is true");
835         error.SetErrorToGenericError();
836         error.SetErrorString(unsupported_opcode_error);
837         return false;
838       }
839 
840       // The semantics of Alloca are:
841       //   Create a region R of virtual memory of type T, backed by a data
842       //   buffer
843       //   Create a region P of virtual memory of type T*, backed by a data
844       //   buffer
845       //   Write the virtual address of R into P
846 
847       Type *T = alloca_inst->getAllocatedType();
848       Type *Tptr = alloca_inst->getType();
849 
850       lldb::addr_t R = frame.Malloc(T);
851 
852       if (R == LLDB_INVALID_ADDRESS) {
853         if (log)
854           log->Printf("Couldn't allocate memory for an AllocaInst");
855         error.SetErrorToGenericError();
856         error.SetErrorString(memory_allocation_error);
857         return false;
858       }
859 
860       lldb::addr_t P = frame.Malloc(Tptr);
861 
862       if (P == LLDB_INVALID_ADDRESS) {
863         if (log)
864           log->Printf("Couldn't allocate the result pointer for an AllocaInst");
865         error.SetErrorToGenericError();
866         error.SetErrorString(memory_allocation_error);
867         return false;
868       }
869 
870       lldb_private::Error write_error;
871 
872       execution_unit.WritePointerToMemory(P, R, write_error);
873 
874       if (!write_error.Success()) {
875         if (log)
876           log->Printf("Couldn't write the result pointer for an AllocaInst");
877         error.SetErrorToGenericError();
878         error.SetErrorString(memory_write_error);
879         lldb_private::Error free_error;
880         execution_unit.Free(P, free_error);
881         execution_unit.Free(R, free_error);
882         return false;
883       }
884 
885       frame.m_values[alloca_inst] = P;
886 
887       if (log) {
888         log->Printf("Interpreted an AllocaInst");
889         log->Printf("  R : 0x%" PRIx64, R);
890         log->Printf("  P : 0x%" PRIx64, P);
891       }
892     } break;
893     case Instruction::BitCast:
894     case Instruction::ZExt: {
895       const CastInst *cast_inst = dyn_cast<CastInst>(inst);
896 
897       if (!cast_inst) {
898         if (log)
899           log->Printf(
900               "getOpcode() returns %s, but instruction is not a BitCastInst",
901               cast_inst->getOpcodeName());
902         error.SetErrorToGenericError();
903         error.SetErrorString(interpreter_internal_error);
904         return false;
905       }
906 
907       Value *source = cast_inst->getOperand(0);
908 
909       lldb_private::Scalar S;
910 
911       if (!frame.EvaluateValue(S, source, module)) {
912         if (log)
913           log->Printf("Couldn't evaluate %s", PrintValue(source).c_str());
914         error.SetErrorToGenericError();
915         error.SetErrorString(bad_value_error);
916         return false;
917       }
918 
919       frame.AssignValue(inst, S, module);
920     } break;
921     case Instruction::SExt: {
922       const CastInst *cast_inst = dyn_cast<CastInst>(inst);
923 
924       if (!cast_inst) {
925         if (log)
926           log->Printf(
927               "getOpcode() returns %s, but instruction is not a BitCastInst",
928               cast_inst->getOpcodeName());
929         error.SetErrorToGenericError();
930         error.SetErrorString(interpreter_internal_error);
931         return false;
932       }
933 
934       Value *source = cast_inst->getOperand(0);
935 
936       lldb_private::Scalar S;
937 
938       if (!frame.EvaluateValue(S, source, module)) {
939         if (log)
940           log->Printf("Couldn't evaluate %s", PrintValue(source).c_str());
941         error.SetErrorToGenericError();
942         error.SetErrorString(bad_value_error);
943         return false;
944       }
945 
946       S.MakeSigned();
947 
948       lldb_private::Scalar S_signextend(S.SLongLong());
949 
950       frame.AssignValue(inst, S_signextend, module);
951     } break;
952     case Instruction::Br: {
953       const BranchInst *br_inst = dyn_cast<BranchInst>(inst);
954 
955       if (!br_inst) {
956         if (log)
957           log->Printf(
958               "getOpcode() returns Br, but instruction is not a BranchInst");
959         error.SetErrorToGenericError();
960         error.SetErrorString(interpreter_internal_error);
961         return false;
962       }
963 
964       if (br_inst->isConditional()) {
965         Value *condition = br_inst->getCondition();
966 
967         lldb_private::Scalar C;
968 
969         if (!frame.EvaluateValue(C, condition, module)) {
970           if (log)
971             log->Printf("Couldn't evaluate %s", PrintValue(condition).c_str());
972           error.SetErrorToGenericError();
973           error.SetErrorString(bad_value_error);
974           return false;
975         }
976 
977         if (!C.IsZero())
978           frame.Jump(br_inst->getSuccessor(0));
979         else
980           frame.Jump(br_inst->getSuccessor(1));
981 
982         if (log) {
983           log->Printf("Interpreted a BrInst with a condition");
984           log->Printf("  cond : %s", frame.SummarizeValue(condition).c_str());
985         }
986       } else {
987         frame.Jump(br_inst->getSuccessor(0));
988 
989         if (log) {
990           log->Printf("Interpreted a BrInst with no condition");
991         }
992       }
993     }
994       continue;
995     case Instruction::PHI: {
996       const PHINode *phi_inst = dyn_cast<PHINode>(inst);
997 
998       if (!phi_inst) {
999         if (log)
1000           log->Printf(
1001               "getOpcode() returns PHI, but instruction is not a PHINode");
1002         error.SetErrorToGenericError();
1003         error.SetErrorString(interpreter_internal_error);
1004         return false;
1005       }
1006       if (!frame.m_prev_bb) {
1007         if (log)
1008           log->Printf("Encountered PHI node without having jumped from another "
1009                       "basic block");
1010         error.SetErrorToGenericError();
1011         error.SetErrorString(interpreter_internal_error);
1012         return false;
1013       }
1014 
1015       Value *value = phi_inst->getIncomingValueForBlock(frame.m_prev_bb);
1016       lldb_private::Scalar result;
1017       if (!frame.EvaluateValue(result, value, module)) {
1018         if (log)
1019           log->Printf("Couldn't evaluate %s", PrintValue(value).c_str());
1020         error.SetErrorToGenericError();
1021         error.SetErrorString(bad_value_error);
1022         return false;
1023       }
1024       frame.AssignValue(inst, result, module);
1025 
1026       if (log) {
1027         log->Printf("Interpreted a %s", inst->getOpcodeName());
1028         log->Printf("  Incoming value : %s",
1029                     frame.SummarizeValue(value).c_str());
1030       }
1031     } break;
1032     case Instruction::GetElementPtr: {
1033       const GetElementPtrInst *gep_inst = dyn_cast<GetElementPtrInst>(inst);
1034 
1035       if (!gep_inst) {
1036         if (log)
1037           log->Printf("getOpcode() returns GetElementPtr, but instruction is "
1038                       "not a GetElementPtrInst");
1039         error.SetErrorToGenericError();
1040         error.SetErrorString(interpreter_internal_error);
1041         return false;
1042       }
1043 
1044       const Value *pointer_operand = gep_inst->getPointerOperand();
1045       Type *src_elem_ty = gep_inst->getSourceElementType();
1046 
1047       lldb_private::Scalar P;
1048 
1049       if (!frame.EvaluateValue(P, pointer_operand, module)) {
1050         if (log)
1051           log->Printf("Couldn't evaluate %s",
1052                       PrintValue(pointer_operand).c_str());
1053         error.SetErrorToGenericError();
1054         error.SetErrorString(bad_value_error);
1055         return false;
1056       }
1057 
1058       typedef SmallVector<Value *, 8> IndexVector;
1059       typedef IndexVector::iterator IndexIterator;
1060 
1061       SmallVector<Value *, 8> indices(gep_inst->idx_begin(),
1062                                       gep_inst->idx_end());
1063 
1064       SmallVector<Value *, 8> const_indices;
1065 
1066       for (IndexIterator ii = indices.begin(), ie = indices.end(); ii != ie;
1067            ++ii) {
1068         ConstantInt *constant_index = dyn_cast<ConstantInt>(*ii);
1069 
1070         if (!constant_index) {
1071           lldb_private::Scalar I;
1072 
1073           if (!frame.EvaluateValue(I, *ii, module)) {
1074             if (log)
1075               log->Printf("Couldn't evaluate %s", PrintValue(*ii).c_str());
1076             error.SetErrorToGenericError();
1077             error.SetErrorString(bad_value_error);
1078             return false;
1079           }
1080 
1081           if (log)
1082             log->Printf("Evaluated constant index %s as %llu",
1083                         PrintValue(*ii).c_str(),
1084                         I.ULongLong(LLDB_INVALID_ADDRESS));
1085 
1086           constant_index = cast<ConstantInt>(ConstantInt::get(
1087               (*ii)->getType(), I.ULongLong(LLDB_INVALID_ADDRESS)));
1088         }
1089 
1090         const_indices.push_back(constant_index);
1091       }
1092 
1093       uint64_t offset =
1094           data_layout.getIndexedOffsetInType(src_elem_ty, const_indices);
1095 
1096       lldb_private::Scalar Poffset = P + offset;
1097 
1098       frame.AssignValue(inst, Poffset, module);
1099 
1100       if (log) {
1101         log->Printf("Interpreted a GetElementPtrInst");
1102         log->Printf("  P       : %s",
1103                     frame.SummarizeValue(pointer_operand).c_str());
1104         log->Printf("  Poffset : %s", frame.SummarizeValue(inst).c_str());
1105       }
1106     } break;
1107     case Instruction::ICmp: {
1108       const ICmpInst *icmp_inst = dyn_cast<ICmpInst>(inst);
1109 
1110       if (!icmp_inst) {
1111         if (log)
1112           log->Printf(
1113               "getOpcode() returns ICmp, but instruction is not an ICmpInst");
1114         error.SetErrorToGenericError();
1115         error.SetErrorString(interpreter_internal_error);
1116         return false;
1117       }
1118 
1119       CmpInst::Predicate predicate = icmp_inst->getPredicate();
1120 
1121       Value *lhs = inst->getOperand(0);
1122       Value *rhs = inst->getOperand(1);
1123 
1124       lldb_private::Scalar L;
1125       lldb_private::Scalar R;
1126 
1127       if (!frame.EvaluateValue(L, lhs, module)) {
1128         if (log)
1129           log->Printf("Couldn't evaluate %s", PrintValue(lhs).c_str());
1130         error.SetErrorToGenericError();
1131         error.SetErrorString(bad_value_error);
1132         return false;
1133       }
1134 
1135       if (!frame.EvaluateValue(R, rhs, module)) {
1136         if (log)
1137           log->Printf("Couldn't evaluate %s", PrintValue(rhs).c_str());
1138         error.SetErrorToGenericError();
1139         error.SetErrorString(bad_value_error);
1140         return false;
1141       }
1142 
1143       lldb_private::Scalar result;
1144 
1145       switch (predicate) {
1146       default:
1147         return false;
1148       case CmpInst::ICMP_EQ:
1149         result = (L == R);
1150         break;
1151       case CmpInst::ICMP_NE:
1152         result = (L != R);
1153         break;
1154       case CmpInst::ICMP_UGT:
1155         L.MakeUnsigned();
1156         R.MakeUnsigned();
1157         result = (L > R);
1158         break;
1159       case CmpInst::ICMP_UGE:
1160         L.MakeUnsigned();
1161         R.MakeUnsigned();
1162         result = (L >= R);
1163         break;
1164       case CmpInst::ICMP_ULT:
1165         L.MakeUnsigned();
1166         R.MakeUnsigned();
1167         result = (L < R);
1168         break;
1169       case CmpInst::ICMP_ULE:
1170         L.MakeUnsigned();
1171         R.MakeUnsigned();
1172         result = (L <= R);
1173         break;
1174       case CmpInst::ICMP_SGT:
1175         L.MakeSigned();
1176         R.MakeSigned();
1177         result = (L > R);
1178         break;
1179       case CmpInst::ICMP_SGE:
1180         L.MakeSigned();
1181         R.MakeSigned();
1182         result = (L >= R);
1183         break;
1184       case CmpInst::ICMP_SLT:
1185         L.MakeSigned();
1186         R.MakeSigned();
1187         result = (L < R);
1188         break;
1189       case CmpInst::ICMP_SLE:
1190         L.MakeSigned();
1191         R.MakeSigned();
1192         result = (L <= R);
1193         break;
1194       }
1195 
1196       frame.AssignValue(inst, result, module);
1197 
1198       if (log) {
1199         log->Printf("Interpreted an ICmpInst");
1200         log->Printf("  L : %s", frame.SummarizeValue(lhs).c_str());
1201         log->Printf("  R : %s", frame.SummarizeValue(rhs).c_str());
1202         log->Printf("  = : %s", frame.SummarizeValue(inst).c_str());
1203       }
1204     } break;
1205     case Instruction::IntToPtr: {
1206       const IntToPtrInst *int_to_ptr_inst = dyn_cast<IntToPtrInst>(inst);
1207 
1208       if (!int_to_ptr_inst) {
1209         if (log)
1210           log->Printf("getOpcode() returns IntToPtr, but instruction is not an "
1211                       "IntToPtrInst");
1212         error.SetErrorToGenericError();
1213         error.SetErrorString(interpreter_internal_error);
1214         return false;
1215       }
1216 
1217       Value *src_operand = int_to_ptr_inst->getOperand(0);
1218 
1219       lldb_private::Scalar I;
1220 
1221       if (!frame.EvaluateValue(I, src_operand, module)) {
1222         if (log)
1223           log->Printf("Couldn't evaluate %s", PrintValue(src_operand).c_str());
1224         error.SetErrorToGenericError();
1225         error.SetErrorString(bad_value_error);
1226         return false;
1227       }
1228 
1229       frame.AssignValue(inst, I, module);
1230 
1231       if (log) {
1232         log->Printf("Interpreted an IntToPtr");
1233         log->Printf("  Src : %s", frame.SummarizeValue(src_operand).c_str());
1234         log->Printf("  =   : %s", frame.SummarizeValue(inst).c_str());
1235       }
1236     } break;
1237     case Instruction::PtrToInt: {
1238       const PtrToIntInst *ptr_to_int_inst = dyn_cast<PtrToIntInst>(inst);
1239 
1240       if (!ptr_to_int_inst) {
1241         if (log)
1242           log->Printf("getOpcode() returns PtrToInt, but instruction is not an "
1243                       "PtrToIntInst");
1244         error.SetErrorToGenericError();
1245         error.SetErrorString(interpreter_internal_error);
1246         return false;
1247       }
1248 
1249       Value *src_operand = ptr_to_int_inst->getOperand(0);
1250 
1251       lldb_private::Scalar I;
1252 
1253       if (!frame.EvaluateValue(I, src_operand, module)) {
1254         if (log)
1255           log->Printf("Couldn't evaluate %s", PrintValue(src_operand).c_str());
1256         error.SetErrorToGenericError();
1257         error.SetErrorString(bad_value_error);
1258         return false;
1259       }
1260 
1261       frame.AssignValue(inst, I, module);
1262 
1263       if (log) {
1264         log->Printf("Interpreted a PtrToInt");
1265         log->Printf("  Src : %s", frame.SummarizeValue(src_operand).c_str());
1266         log->Printf("  =   : %s", frame.SummarizeValue(inst).c_str());
1267       }
1268     } break;
1269     case Instruction::Trunc: {
1270       const TruncInst *trunc_inst = dyn_cast<TruncInst>(inst);
1271 
1272       if (!trunc_inst) {
1273         if (log)
1274           log->Printf(
1275               "getOpcode() returns Trunc, but instruction is not a TruncInst");
1276         error.SetErrorToGenericError();
1277         error.SetErrorString(interpreter_internal_error);
1278         return false;
1279       }
1280 
1281       Value *src_operand = trunc_inst->getOperand(0);
1282 
1283       lldb_private::Scalar I;
1284 
1285       if (!frame.EvaluateValue(I, src_operand, module)) {
1286         if (log)
1287           log->Printf("Couldn't evaluate %s", PrintValue(src_operand).c_str());
1288         error.SetErrorToGenericError();
1289         error.SetErrorString(bad_value_error);
1290         return false;
1291       }
1292 
1293       frame.AssignValue(inst, I, module);
1294 
1295       if (log) {
1296         log->Printf("Interpreted a Trunc");
1297         log->Printf("  Src : %s", frame.SummarizeValue(src_operand).c_str());
1298         log->Printf("  =   : %s", frame.SummarizeValue(inst).c_str());
1299       }
1300     } break;
1301     case Instruction::Load: {
1302       const LoadInst *load_inst = dyn_cast<LoadInst>(inst);
1303 
1304       if (!load_inst) {
1305         if (log)
1306           log->Printf(
1307               "getOpcode() returns Load, but instruction is not a LoadInst");
1308         error.SetErrorToGenericError();
1309         error.SetErrorString(interpreter_internal_error);
1310         return false;
1311       }
1312 
1313       // The semantics of Load are:
1314       //   Create a region D that will contain the loaded data
1315       //   Resolve the region P containing a pointer
1316       //   Dereference P to get the region R that the data should be loaded from
1317       //   Transfer a unit of type type(D) from R to D
1318 
1319       const Value *pointer_operand = load_inst->getPointerOperand();
1320 
1321       Type *pointer_ty = pointer_operand->getType();
1322       PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
1323       if (!pointer_ptr_ty) {
1324         if (log)
1325           log->Printf("getPointerOperand()->getType() is not a PointerType");
1326         error.SetErrorToGenericError();
1327         error.SetErrorString(interpreter_internal_error);
1328         return false;
1329       }
1330       Type *target_ty = pointer_ptr_ty->getElementType();
1331 
1332       lldb::addr_t D = frame.ResolveValue(load_inst, module);
1333       lldb::addr_t P = frame.ResolveValue(pointer_operand, module);
1334 
1335       if (D == LLDB_INVALID_ADDRESS) {
1336         if (log)
1337           log->Printf("LoadInst's value doesn't resolve to anything");
1338         error.SetErrorToGenericError();
1339         error.SetErrorString(bad_value_error);
1340         return false;
1341       }
1342 
1343       if (P == LLDB_INVALID_ADDRESS) {
1344         if (log)
1345           log->Printf("LoadInst's pointer doesn't resolve to anything");
1346         error.SetErrorToGenericError();
1347         error.SetErrorString(bad_value_error);
1348         return false;
1349       }
1350 
1351       lldb::addr_t R;
1352       lldb_private::Error read_error;
1353       execution_unit.ReadPointerFromMemory(&R, P, read_error);
1354 
1355       if (!read_error.Success()) {
1356         if (log)
1357           log->Printf("Couldn't read the address to be loaded for a LoadInst");
1358         error.SetErrorToGenericError();
1359         error.SetErrorString(memory_read_error);
1360         return false;
1361       }
1362 
1363       size_t target_size = data_layout.getTypeStoreSize(target_ty);
1364       lldb_private::DataBufferHeap buffer(target_size, 0);
1365 
1366       read_error.Clear();
1367       execution_unit.ReadMemory(buffer.GetBytes(), R, buffer.GetByteSize(),
1368                                 read_error);
1369       if (!read_error.Success()) {
1370         if (log)
1371           log->Printf("Couldn't read from a region on behalf of a LoadInst");
1372         error.SetErrorToGenericError();
1373         error.SetErrorString(memory_read_error);
1374         return false;
1375       }
1376 
1377       lldb_private::Error write_error;
1378       execution_unit.WriteMemory(D, buffer.GetBytes(), buffer.GetByteSize(),
1379                                  write_error);
1380       if (!write_error.Success()) {
1381         if (log)
1382           log->Printf("Couldn't write to a region on behalf of a LoadInst");
1383         error.SetErrorToGenericError();
1384         error.SetErrorString(memory_read_error);
1385         return false;
1386       }
1387 
1388       if (log) {
1389         log->Printf("Interpreted a LoadInst");
1390         log->Printf("  P : 0x%" PRIx64, P);
1391         log->Printf("  R : 0x%" PRIx64, R);
1392         log->Printf("  D : 0x%" PRIx64, D);
1393       }
1394     } break;
1395     case Instruction::Ret: {
1396       return true;
1397     }
1398     case Instruction::Store: {
1399       const StoreInst *store_inst = dyn_cast<StoreInst>(inst);
1400 
1401       if (!store_inst) {
1402         if (log)
1403           log->Printf(
1404               "getOpcode() returns Store, but instruction is not a StoreInst");
1405         error.SetErrorToGenericError();
1406         error.SetErrorString(interpreter_internal_error);
1407         return false;
1408       }
1409 
1410       // The semantics of Store are:
1411       //   Resolve the region D containing the data to be stored
1412       //   Resolve the region P containing a pointer
1413       //   Dereference P to get the region R that the data should be stored in
1414       //   Transfer a unit of type type(D) from D to R
1415 
1416       const Value *value_operand = store_inst->getValueOperand();
1417       const Value *pointer_operand = store_inst->getPointerOperand();
1418 
1419       Type *pointer_ty = pointer_operand->getType();
1420       PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
1421       if (!pointer_ptr_ty)
1422         return false;
1423       Type *target_ty = pointer_ptr_ty->getElementType();
1424 
1425       lldb::addr_t D = frame.ResolveValue(value_operand, module);
1426       lldb::addr_t P = frame.ResolveValue(pointer_operand, module);
1427 
1428       if (D == LLDB_INVALID_ADDRESS) {
1429         if (log)
1430           log->Printf("StoreInst's value doesn't resolve to anything");
1431         error.SetErrorToGenericError();
1432         error.SetErrorString(bad_value_error);
1433         return false;
1434       }
1435 
1436       if (P == LLDB_INVALID_ADDRESS) {
1437         if (log)
1438           log->Printf("StoreInst's pointer doesn't resolve to anything");
1439         error.SetErrorToGenericError();
1440         error.SetErrorString(bad_value_error);
1441         return false;
1442       }
1443 
1444       lldb::addr_t R;
1445       lldb_private::Error read_error;
1446       execution_unit.ReadPointerFromMemory(&R, P, read_error);
1447 
1448       if (!read_error.Success()) {
1449         if (log)
1450           log->Printf("Couldn't read the address to be loaded for a LoadInst");
1451         error.SetErrorToGenericError();
1452         error.SetErrorString(memory_read_error);
1453         return false;
1454       }
1455 
1456       size_t target_size = data_layout.getTypeStoreSize(target_ty);
1457       lldb_private::DataBufferHeap buffer(target_size, 0);
1458 
1459       read_error.Clear();
1460       execution_unit.ReadMemory(buffer.GetBytes(), D, buffer.GetByteSize(),
1461                                 read_error);
1462       if (!read_error.Success()) {
1463         if (log)
1464           log->Printf("Couldn't read from a region on behalf of a StoreInst");
1465         error.SetErrorToGenericError();
1466         error.SetErrorString(memory_read_error);
1467         return false;
1468       }
1469 
1470       lldb_private::Error write_error;
1471       execution_unit.WriteMemory(R, buffer.GetBytes(), buffer.GetByteSize(),
1472                                  write_error);
1473       if (!write_error.Success()) {
1474         if (log)
1475           log->Printf("Couldn't write to a region on behalf of a StoreInst");
1476         error.SetErrorToGenericError();
1477         error.SetErrorString(memory_write_error);
1478         return false;
1479       }
1480 
1481       if (log) {
1482         log->Printf("Interpreted a StoreInst");
1483         log->Printf("  D : 0x%" PRIx64, D);
1484         log->Printf("  P : 0x%" PRIx64, P);
1485         log->Printf("  R : 0x%" PRIx64, R);
1486       }
1487     } break;
1488     case Instruction::Call: {
1489       const CallInst *call_inst = dyn_cast<CallInst>(inst);
1490 
1491       if (!call_inst) {
1492         if (log)
1493           log->Printf(
1494               "getOpcode() returns %s, but instruction is not a CallInst",
1495               inst->getOpcodeName());
1496         error.SetErrorToGenericError();
1497         error.SetErrorString(interpreter_internal_error);
1498         return false;
1499       }
1500 
1501       if (CanIgnoreCall(call_inst))
1502         break;
1503 
1504       // Get the return type
1505       llvm::Type *returnType = call_inst->getType();
1506       if (returnType == nullptr) {
1507         error.SetErrorToGenericError();
1508         error.SetErrorString("unable to access return type");
1509         return false;
1510       }
1511 
1512       // Work with void, integer and pointer return types
1513       if (!returnType->isVoidTy() && !returnType->isIntegerTy() &&
1514           !returnType->isPointerTy()) {
1515         error.SetErrorToGenericError();
1516         error.SetErrorString("return type is not supported");
1517         return false;
1518       }
1519 
1520       // Check we can actually get a thread
1521       if (exe_ctx.GetThreadPtr() == nullptr) {
1522         error.SetErrorToGenericError();
1523         error.SetErrorStringWithFormat("unable to acquire thread");
1524         return false;
1525       }
1526 
1527       // Make sure we have a valid process
1528       if (!exe_ctx.GetProcessPtr()) {
1529         error.SetErrorToGenericError();
1530         error.SetErrorStringWithFormat("unable to get the process");
1531         return false;
1532       }
1533 
1534       // Find the address of the callee function
1535       lldb_private::Scalar I;
1536       const llvm::Value *val = call_inst->getCalledValue();
1537 
1538       if (!frame.EvaluateValue(I, val, module)) {
1539         error.SetErrorToGenericError();
1540         error.SetErrorString("unable to get address of function");
1541         return false;
1542       }
1543       lldb_private::Address funcAddr(I.ULongLong(LLDB_INVALID_ADDRESS));
1544 
1545       lldb_private::DiagnosticManager diagnostics;
1546       lldb_private::EvaluateExpressionOptions options;
1547 
1548       // We generally receive a function pointer which we must dereference
1549       llvm::Type *prototype = val->getType();
1550       if (!prototype->isPointerTy()) {
1551         error.SetErrorToGenericError();
1552         error.SetErrorString("call need function pointer");
1553         return false;
1554       }
1555 
1556       // Dereference the function pointer
1557       prototype = prototype->getPointerElementType();
1558       if (!(prototype->isFunctionTy() || prototype->isFunctionVarArg())) {
1559         error.SetErrorToGenericError();
1560         error.SetErrorString("call need function pointer");
1561         return false;
1562       }
1563 
1564       // Find number of arguments
1565       const int numArgs = call_inst->getNumArgOperands();
1566 
1567       // We work with a fixed array of 16 arguments which is our upper limit
1568       static lldb_private::ABI::CallArgument rawArgs[16];
1569       if (numArgs >= 16) {
1570         error.SetErrorToGenericError();
1571         error.SetErrorStringWithFormat("function takes too many arguments");
1572         return false;
1573       }
1574 
1575       // Push all function arguments to the argument list that will
1576       // be passed to the call function thread plan
1577       for (int i = 0; i < numArgs; i++) {
1578         // Get details of this argument
1579         llvm::Value *arg_op = call_inst->getArgOperand(i);
1580         llvm::Type *arg_ty = arg_op->getType();
1581 
1582         // Ensure that this argument is an supported type
1583         if (!arg_ty->isIntegerTy() && !arg_ty->isPointerTy()) {
1584           error.SetErrorToGenericError();
1585           error.SetErrorStringWithFormat("argument %d must be integer type", i);
1586           return false;
1587         }
1588 
1589         // Extract the arguments value
1590         lldb_private::Scalar tmp_op = 0;
1591         if (!frame.EvaluateValue(tmp_op, arg_op, module)) {
1592           error.SetErrorToGenericError();
1593           error.SetErrorStringWithFormat("unable to evaluate argument %d", i);
1594           return false;
1595         }
1596 
1597         // Check if this is a string literal or constant string pointer
1598         if (arg_ty->isPointerTy()) {
1599           // Pointer to just one type
1600           assert(arg_ty->getNumContainedTypes() == 1);
1601 
1602           lldb::addr_t addr = tmp_op.ULongLong();
1603           size_t dataSize = 0;
1604 
1605           if (execution_unit.GetAllocSize(addr, dataSize)) {
1606             // Create the required buffer
1607             rawArgs[i].size = dataSize;
1608             rawArgs[i].data_ap.reset(new uint8_t[dataSize + 1]);
1609 
1610             // Read string from host memory
1611             execution_unit.ReadMemory(rawArgs[i].data_ap.get(), addr, dataSize,
1612                                       error);
1613             if (error.Fail()) {
1614               assert(!"we have failed to read the string from memory");
1615               return false;
1616             }
1617             // Add null terminator
1618             rawArgs[i].data_ap[dataSize] = '\0';
1619             rawArgs[i].type = lldb_private::ABI::CallArgument::HostPointer;
1620           } else {
1621             assert(!"unable to locate host data for transfer to device");
1622             return false;
1623           }
1624         } else /* if ( arg_ty->isPointerTy() ) */
1625         {
1626           rawArgs[i].type = lldb_private::ABI::CallArgument::TargetValue;
1627           // Get argument size in bytes
1628           rawArgs[i].size = arg_ty->getIntegerBitWidth() / 8;
1629           // Push value into argument list for thread plan
1630           rawArgs[i].value = tmp_op.ULongLong();
1631         }
1632       }
1633 
1634       // Pack the arguments into an llvm::array
1635       llvm::ArrayRef<lldb_private::ABI::CallArgument> args(rawArgs, numArgs);
1636 
1637       // Setup a thread plan to call the target function
1638       lldb::ThreadPlanSP call_plan_sp(
1639           new lldb_private::ThreadPlanCallFunctionUsingABI(
1640               exe_ctx.GetThreadRef(), funcAddr, *prototype, *returnType, args,
1641               options));
1642 
1643       // Check if the plan is valid
1644       lldb_private::StreamString ss;
1645       if (!call_plan_sp || !call_plan_sp->ValidatePlan(&ss)) {
1646         error.SetErrorToGenericError();
1647         error.SetErrorStringWithFormat(
1648             "unable to make ThreadPlanCallFunctionUsingABI for 0x%llx",
1649             I.ULongLong());
1650         return false;
1651       }
1652 
1653       exe_ctx.GetProcessPtr()->SetRunningUserExpression(true);
1654 
1655       // Execute the actual function call thread plan
1656       lldb::ExpressionResults res = exe_ctx.GetProcessRef().RunThreadPlan(
1657           exe_ctx, call_plan_sp, options, diagnostics);
1658 
1659       // Check that the thread plan completed successfully
1660       if (res != lldb::ExpressionResults::eExpressionCompleted) {
1661         error.SetErrorToGenericError();
1662         error.SetErrorStringWithFormat("ThreadPlanCallFunctionUsingABI failed");
1663         return false;
1664       }
1665 
1666       exe_ctx.GetProcessPtr()->SetRunningUserExpression(false);
1667 
1668       // Void return type
1669       if (returnType->isVoidTy()) {
1670         // Cant assign to void types, so we leave the frame untouched
1671       } else
1672           // Integer or pointer return type
1673           if (returnType->isIntegerTy() || returnType->isPointerTy()) {
1674         // Get the encapsulated return value
1675         lldb::ValueObjectSP retVal = call_plan_sp.get()->GetReturnValueObject();
1676 
1677         lldb_private::Scalar returnVal = -1;
1678         lldb_private::ValueObject *vobj = retVal.get();
1679 
1680         // Check if the return value is valid
1681         if (vobj == nullptr || retVal.empty()) {
1682           error.SetErrorToGenericError();
1683           error.SetErrorStringWithFormat("unable to get the return value");
1684           return false;
1685         }
1686 
1687         // Extract the return value as a integer
1688         lldb_private::Value &value = vobj->GetValue();
1689         returnVal = value.GetScalar();
1690 
1691         // Push the return value as the result
1692         frame.AssignValue(inst, returnVal, module);
1693       }
1694     } break;
1695     }
1696 
1697     ++frame.m_ii;
1698   }
1699 
1700   if (num_insts >= 4096) {
1701     error.SetErrorToGenericError();
1702     error.SetErrorString(infinite_loop_error);
1703     return false;
1704   }
1705 
1706   return false;
1707 }
1708