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/Core/DataExtractor.h"
11 #include "lldb/Core/Error.h"
12 #include "lldb/Core/Log.h"
13 #include "lldb/Core/Scalar.h"
14 #include "lldb/Core/StreamString.h"
15 #include "lldb/Expression/IRMemoryMap.h"
16 #include "lldb/Expression/IRInterpreter.h"
17 #include "lldb/Host/Endian.h"
18 
19 #include "llvm/IR/Constants.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/Function.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/Intrinsics.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/Support/raw_ostream.h"
26 
27 #include <map>
28 
29 using namespace llvm;
30 
31 static std::string
32 PrintValue(const Value *value, bool truncate = false)
33 {
34     std::string s;
35     raw_string_ostream rso(s);
36     value->print(rso);
37     rso.flush();
38     if (truncate)
39         s.resize(s.length() - 1);
40 
41     size_t offset;
42     while ((offset = s.find('\n')) != s.npos)
43         s.erase(offset, 1);
44     while (s[0] == ' ' || s[0] == '\t')
45         s.erase(0, 1);
46 
47     return s;
48 }
49 
50 static std::string
51 PrintType(const Type *type, bool truncate = false)
52 {
53     std::string s;
54     raw_string_ostream rso(s);
55     type->print(rso);
56     rso.flush();
57     if (truncate)
58         s.resize(s.length() - 1);
59     return s;
60 }
61 
62 static bool
63 CanIgnoreCall (const CallInst *call)
64 {
65     const llvm::Function *called_function = call->getCalledFunction();
66 
67     if (!called_function)
68         return false;
69 
70     if (called_function->isIntrinsic())
71     {
72         switch (called_function->getIntrinsicID())
73         {
74         default:
75             break;
76         case llvm::Intrinsic::dbg_declare:
77         case llvm::Intrinsic::dbg_value:
78             return true;
79         }
80     }
81 
82     return false;
83 }
84 
85 class InterpreterStackFrame
86 {
87 public:
88     typedef std::map <const Value*, lldb::addr_t> ValueMap;
89 
90     ValueMap                                m_values;
91     DataLayout                             &m_target_data;
92     lldb_private::IRMemoryMap              &m_memory_map;
93     const BasicBlock                       *m_bb;
94     BasicBlock::const_iterator              m_ii;
95     BasicBlock::const_iterator              m_ie;
96 
97     lldb::addr_t                            m_frame_process_address;
98     size_t                                  m_frame_size;
99     lldb::addr_t                            m_stack_pointer;
100 
101     lldb::ByteOrder                         m_byte_order;
102     size_t                                  m_addr_byte_size;
103 
104     InterpreterStackFrame (DataLayout &target_data,
105                            lldb_private::IRMemoryMap &memory_map,
106                            lldb::addr_t stack_frame_bottom,
107                            lldb::addr_t stack_frame_top) :
108         m_target_data (target_data),
109         m_memory_map (memory_map)
110     {
111         m_byte_order = (target_data.isLittleEndian() ? lldb::eByteOrderLittle : lldb::eByteOrderBig);
112         m_addr_byte_size = (target_data.getPointerSize(0));
113 
114         m_frame_process_address = stack_frame_bottom;
115         m_frame_size = stack_frame_top - stack_frame_bottom;
116         m_stack_pointer = stack_frame_top;
117     }
118 
119     ~InterpreterStackFrame ()
120     {
121     }
122 
123     void Jump (const BasicBlock *bb)
124     {
125         m_bb = bb;
126         m_ii = m_bb->begin();
127         m_ie = m_bb->end();
128     }
129 
130     std::string SummarizeValue (const Value *value)
131     {
132         lldb_private::StreamString ss;
133 
134         ss.Printf("%s", PrintValue(value).c_str());
135 
136         ValueMap::iterator i = m_values.find(value);
137 
138         if (i != m_values.end())
139         {
140             lldb::addr_t addr = i->second;
141 
142             ss.Printf(" 0x%llx", (unsigned long long)addr);
143         }
144 
145         return ss.GetString();
146     }
147 
148     bool AssignToMatchType (lldb_private::Scalar &scalar, uint64_t u64value, Type *type)
149     {
150         size_t type_size = m_target_data.getTypeStoreSize(type);
151 
152         switch (type_size)
153         {
154         case 1:
155             scalar = (uint8_t)u64value;
156             break;
157         case 2:
158             scalar = (uint16_t)u64value;
159             break;
160         case 4:
161             scalar = (uint32_t)u64value;
162             break;
163         case 8:
164             scalar = (uint64_t)u64value;
165             break;
166         default:
167             return false;
168         }
169 
170         return true;
171     }
172 
173     bool EvaluateValue (lldb_private::Scalar &scalar, const Value *value, Module &module)
174     {
175         const Constant *constant = dyn_cast<Constant>(value);
176 
177         if (constant)
178         {
179             APInt value_apint;
180 
181             if (!ResolveConstantValue(value_apint, constant))
182                 return false;
183 
184             return AssignToMatchType(scalar, value_apint.getLimitedValue(), value->getType());
185         }
186         else
187         {
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_memory_map.GetMemoryData(value_extractor, process_address, value_size, extract_error);
195 
196             if (!extract_error.Success())
197                 return false;
198 
199             lldb::offset_t offset = 0;
200             if (value_size == 1 || value_size == 2 || value_size == 4 || value_size == 8)
201             {
202                 uint64_t u64value = value_extractor.GetMaxU64(&offset, value_size);
203                 return AssignToMatchType(scalar, u64value, value->getType());
204             }
205         }
206 
207         return false;
208     }
209 
210     bool AssignValue (const Value *value, lldb_private::Scalar &scalar, Module &module)
211     {
212         lldb::addr_t process_address = ResolveValue (value, module);
213 
214         if (process_address == LLDB_INVALID_ADDRESS)
215             return false;
216 
217         lldb_private::Scalar cast_scalar;
218 
219         if (!AssignToMatchType(cast_scalar, scalar.GetRawBits64(0), value->getType()))
220             return false;
221 
222         size_t value_byte_size = m_target_data.getTypeStoreSize(value->getType());
223 
224         lldb_private::DataBufferHeap buf(value_byte_size, 0);
225 
226         lldb_private::Error get_data_error;
227 
228         if (!cast_scalar.GetAsMemoryData(buf.GetBytes(), buf.GetByteSize(), m_byte_order, get_data_error))
229             return false;
230 
231         lldb_private::Error write_error;
232 
233         m_memory_map.WriteMemory(process_address, buf.GetBytes(), buf.GetByteSize(), write_error);
234 
235         return write_error.Success();
236     }
237 
238     bool ResolveConstantValue (APInt &value, const Constant *constant)
239     {
240         switch (constant->getValueID())
241         {
242         default:
243             break;
244         case Value::ConstantIntVal:
245             if (const ConstantInt *constant_int = dyn_cast<ConstantInt>(constant))
246             {
247                 value = constant_int->getValue();
248                 return true;
249             }
250             break;
251         case Value::ConstantFPVal:
252             if (const ConstantFP *constant_fp = dyn_cast<ConstantFP>(constant))
253             {
254                 value = constant_fp->getValueAPF().bitcastToAPInt();
255                 return true;
256             }
257             break;
258         case Value::ConstantExprVal:
259             if (const ConstantExpr *constant_expr = dyn_cast<ConstantExpr>(constant))
260             {
261                 switch (constant_expr->getOpcode())
262                 {
263                     default:
264                         return false;
265                     case Instruction::IntToPtr:
266                     case Instruction::PtrToInt:
267                     case Instruction::BitCast:
268                         return ResolveConstantValue(value, constant_expr->getOperand(0));
269                     case Instruction::GetElementPtr:
270                     {
271                         ConstantExpr::const_op_iterator op_cursor = constant_expr->op_begin();
272                         ConstantExpr::const_op_iterator op_end = constant_expr->op_end();
273 
274                         Constant *base = dyn_cast<Constant>(*op_cursor);
275 
276                         if (!base)
277                             return false;
278 
279                         if (!ResolveConstantValue(value, base))
280                             return false;
281 
282                         op_cursor++;
283 
284                         if (op_cursor == op_end)
285                             return true; // no offset to apply!
286 
287                         SmallVector <Value *, 8> indices (op_cursor, op_end);
288 
289                         uint64_t offset = m_target_data.getIndexedOffset(base->getType(), indices);
290 
291                         const bool is_signed = true;
292                         value += APInt(value.getBitWidth(), offset, is_signed);
293 
294                         return true;
295                     }
296                 }
297             }
298             break;
299         case Value::ConstantPointerNullVal:
300             if (isa<ConstantPointerNull>(constant))
301             {
302                 value = APInt(m_target_data.getPointerSizeInBits(), 0);
303                 return true;
304             }
305             break;
306         }
307         return false;
308     }
309 
310     bool MakeArgument(const Argument *value, uint64_t address)
311     {
312         lldb::addr_t data_address = Malloc(value->getType());
313 
314         if (data_address == LLDB_INVALID_ADDRESS)
315             return false;
316 
317         lldb_private::Error write_error;
318 
319         m_memory_map.WritePointerToMemory(data_address, address, write_error);
320 
321         if (!write_error.Success())
322         {
323             lldb_private::Error free_error;
324             m_memory_map.Free(data_address, free_error);
325             return false;
326         }
327 
328         m_values[value] = data_address;
329 
330         lldb_private::Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
331 
332         if (log)
333         {
334             log->Printf("Made an allocation for argument %s", PrintValue(value).c_str());
335             log->Printf("  Data region    : %llx", (unsigned long long)address);
336             log->Printf("  Ref region     : %llx", (unsigned long long)data_address);
337         }
338 
339         return true;
340     }
341 
342     bool ResolveConstant (lldb::addr_t process_address, const Constant *constant)
343     {
344         APInt resolved_value;
345 
346         if (!ResolveConstantValue(resolved_value, constant))
347             return false;
348 
349         lldb_private::StreamString buffer (lldb_private::Stream::eBinary,
350                                            m_memory_map.GetAddressByteSize(),
351                                            m_memory_map.GetByteOrder());
352 
353         size_t constant_size = m_target_data.getTypeStoreSize(constant->getType());
354 
355         const uint64_t *raw_data = resolved_value.getRawData();
356 
357         buffer.PutRawBytes(raw_data, constant_size, lldb::endian::InlHostByteOrder());
358 
359         lldb_private::Error write_error;
360 
361         m_memory_map.WriteMemory(process_address, (const uint8_t*)buffer.GetData(), constant_size, write_error);
362 
363         return write_error.Success();
364     }
365 
366     lldb::addr_t Malloc (size_t size, uint8_t byte_alignment)
367     {
368         lldb::addr_t ret = m_stack_pointer;
369 
370         ret -= size;
371         ret -= (ret % byte_alignment);
372 
373         if (ret < m_frame_process_address)
374             return LLDB_INVALID_ADDRESS;
375 
376         m_stack_pointer = ret;
377         return ret;
378     }
379 
380     lldb::addr_t MallocPointer ()
381     {
382         return Malloc(m_target_data.getPointerSize(), m_target_data.getPointerPrefAlignment());
383     }
384 
385     lldb::addr_t Malloc (llvm::Type *type)
386     {
387         lldb_private::Error alloc_error;
388 
389         return Malloc(m_target_data.getTypeAllocSize(type), m_target_data.getPrefTypeAlignment(type));
390     }
391 
392     std::string PrintData (lldb::addr_t addr, llvm::Type *type)
393     {
394         size_t length = m_target_data.getTypeStoreSize(type);
395 
396         lldb_private::DataBufferHeap buf(length, 0);
397 
398         lldb_private::Error read_error;
399 
400         m_memory_map.ReadMemory(buf.GetBytes(), addr, length, read_error);
401 
402         if (!read_error.Success())
403             return std::string("<couldn't read data>");
404 
405         lldb_private::StreamString ss;
406 
407         for (size_t i = 0; i < length; i++)
408         {
409             if ((!(i & 0xf)) && i)
410                 ss.Printf("%02hhx - ", buf.GetBytes()[i]);
411             else
412                 ss.Printf("%02hhx ", buf.GetBytes()[i]);
413         }
414 
415         return ss.GetString();
416     }
417 
418     lldb::addr_t ResolveValue (const Value *value, Module &module)
419     {
420         ValueMap::iterator i = m_values.find(value);
421 
422         if (i != m_values.end())
423             return i->second;
424 
425         // Fall back and allocate space [allocation type Alloca]
426 
427         lldb::addr_t data_address = Malloc(value->getType());
428 
429         if (const Constant *constant = dyn_cast<Constant>(value))
430         {
431             if (!ResolveConstant (data_address, constant))
432             {
433                 lldb_private::Error free_error;
434                 m_memory_map.Free(data_address, free_error);
435                 return LLDB_INVALID_ADDRESS;
436             }
437         }
438 
439         m_values[value] = data_address;
440         return data_address;
441     }
442 };
443 
444 static const char *unsupported_opcode_error         = "Interpreter doesn't handle one of the expression's opcodes";
445 static const char *unsupported_operand_error        = "Interpreter doesn't handle one of the expression's operands";
446 //static const char *interpreter_initialization_error = "Interpreter couldn't be initialized";
447 static const char *interpreter_internal_error       = "Interpreter encountered an internal error";
448 static const char *bad_value_error                  = "Interpreter couldn't resolve a value during execution";
449 static const char *memory_allocation_error          = "Interpreter couldn't allocate memory";
450 static const char *memory_write_error               = "Interpreter couldn't write to memory";
451 static const char *memory_read_error                = "Interpreter couldn't read from memory";
452 static const char *infinite_loop_error              = "Interpreter ran for too many cycles";
453 //static const char *bad_result_error                 = "Result of expression is in bad memory";
454 
455 bool
456 IRInterpreter::CanInterpret (llvm::Module &module,
457                              llvm::Function &function,
458                              lldb_private::Error &error)
459 {
460     lldb_private::Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
461 
462     bool saw_function_with_body = false;
463 
464     for (Module::iterator fi = module.begin(), fe = module.end();
465          fi != fe;
466          ++fi)
467     {
468         if (fi->begin() != fi->end())
469         {
470             if (saw_function_with_body)
471                 return false;
472             saw_function_with_body = true;
473         }
474     }
475 
476     for (Function::iterator bbi = function.begin(), bbe = function.end();
477          bbi != bbe;
478          ++bbi)
479     {
480         for (BasicBlock::iterator ii = bbi->begin(), ie = bbi->end();
481              ii != ie;
482              ++ii)
483         {
484             switch (ii->getOpcode())
485             {
486             default:
487                 {
488                     if (log)
489                         log->Printf("Unsupported instruction: %s", PrintValue(ii).c_str());
490                     error.SetErrorToGenericError();
491                     error.SetErrorString(unsupported_opcode_error);
492                     return false;
493                 }
494             case Instruction::Add:
495             case Instruction::Alloca:
496             case Instruction::BitCast:
497             case Instruction::Br:
498                 break;
499             case Instruction::Call:
500                 {
501                     CallInst *call_inst = dyn_cast<CallInst>(ii);
502 
503                     if (!call_inst)
504                     {
505                         error.SetErrorToGenericError();
506                         error.SetErrorString(interpreter_internal_error);
507                         return false;
508                     }
509 
510                     if (!CanIgnoreCall(call_inst))
511                     {
512                         if (log)
513                             log->Printf("Unsupported instruction: %s", PrintValue(ii).c_str());
514                         error.SetErrorToGenericError();
515                         error.SetErrorString(unsupported_opcode_error);
516                         return false;
517                     }
518                 }
519                 break;
520             case Instruction::GetElementPtr:
521                 break;
522             case Instruction::ICmp:
523                 {
524                     ICmpInst *icmp_inst = dyn_cast<ICmpInst>(ii);
525 
526                     if (!icmp_inst)
527                     {
528                         error.SetErrorToGenericError();
529                         error.SetErrorString(interpreter_internal_error);
530                         return false;
531                     }
532 
533                     switch (icmp_inst->getPredicate())
534                     {
535                     default:
536                     {
537                         if (log)
538                             log->Printf("Unsupported ICmp predicate: %s", PrintValue(ii).c_str());
539 
540                         error.SetErrorToGenericError();
541                         error.SetErrorString(unsupported_opcode_error);
542                         return false;
543                     }
544                     case CmpInst::ICMP_EQ:
545                     case CmpInst::ICMP_NE:
546                     case CmpInst::ICMP_UGT:
547                     case CmpInst::ICMP_UGE:
548                     case CmpInst::ICMP_ULT:
549                     case CmpInst::ICMP_ULE:
550                     case CmpInst::ICMP_SGT:
551                     case CmpInst::ICMP_SGE:
552                     case CmpInst::ICMP_SLT:
553                     case CmpInst::ICMP_SLE:
554                         break;
555                     }
556                 }
557                 break;
558             case Instruction::And:
559             case Instruction::AShr:
560             case Instruction::IntToPtr:
561             case Instruction::PtrToInt:
562             case Instruction::Load:
563             case Instruction::LShr:
564             case Instruction::Mul:
565             case Instruction::Or:
566             case Instruction::Ret:
567             case Instruction::SDiv:
568             case Instruction::SExt:
569             case Instruction::Shl:
570             case Instruction::SRem:
571             case Instruction::Store:
572             case Instruction::Sub:
573             case Instruction::Trunc:
574             case Instruction::UDiv:
575             case Instruction::URem:
576             case Instruction::Xor:
577             case Instruction::ZExt:
578                 break;
579             }
580 
581             for (int oi = 0, oe = ii->getNumOperands();
582                  oi != oe;
583                  ++oi)
584             {
585                 Value *operand = ii->getOperand(oi);
586                 Type *operand_type = operand->getType();
587 
588                 switch (operand_type->getTypeID())
589                 {
590                 default:
591                     break;
592                 case Type::VectorTyID:
593                     {
594                         if (log)
595                             log->Printf("Unsupported operand type: %s", PrintType(operand_type).c_str());
596                         error.SetErrorString(unsupported_operand_error);
597                         return false;
598                     }
599                 }
600             }
601         }
602 
603     }
604 
605     return true;}
606 
607 bool
608 IRInterpreter::Interpret (llvm::Module &module,
609                           llvm::Function &function,
610                           llvm::ArrayRef<lldb::addr_t> args,
611                           lldb_private::IRMemoryMap &memory_map,
612                           lldb_private::Error &error,
613                           lldb::addr_t stack_frame_bottom,
614                           lldb::addr_t stack_frame_top)
615 {
616     lldb_private::Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
617 
618     if (log)
619     {
620         std::string s;
621         raw_string_ostream oss(s);
622 
623         module.print(oss, NULL);
624 
625         oss.flush();
626 
627         log->Printf("Module as passed in to IRInterpreter::Interpret: \n\"%s\"", s.c_str());
628     }
629 
630     DataLayout data_layout(&module);
631 
632     InterpreterStackFrame frame(data_layout, memory_map, stack_frame_bottom, stack_frame_top);
633 
634     if (frame.m_frame_process_address == LLDB_INVALID_ADDRESS)
635     {
636         error.SetErrorString("Couldn't allocate stack frame");
637     }
638 
639     int arg_index = 0;
640 
641     for (llvm::Function::arg_iterator ai = function.arg_begin(), ae = function.arg_end();
642          ai != ae;
643          ++ai, ++arg_index)
644     {
645         if (args.size() < static_cast<size_t>(arg_index))
646         {
647             error.SetErrorString ("Not enough arguments passed in to function");
648             return false;
649         }
650 
651         lldb::addr_t ptr = args[arg_index];
652 
653         frame.MakeArgument(ai, ptr);
654     }
655 
656     uint32_t num_insts = 0;
657 
658     frame.Jump(function.begin());
659 
660     while (frame.m_ii != frame.m_ie && (++num_insts < 4096))
661     {
662         const Instruction *inst = frame.m_ii;
663 
664         if (log)
665             log->Printf("Interpreting %s", PrintValue(inst).c_str());
666 
667         switch (inst->getOpcode())
668         {
669             default:
670                 break;
671             case Instruction::Call:
672             {
673                 const CallInst *call_inst = dyn_cast<CallInst>(inst);
674 
675                 if (!call_inst)
676                 {
677                     if (log)
678                         log->Printf("getOpcode() returns %s, but instruction is not a CallInst", inst->getOpcodeName());
679                     error.SetErrorToGenericError();
680                     error.SetErrorString(interpreter_internal_error);
681                     return false;
682                 }
683 
684                 if (!CanIgnoreCall(call_inst))
685                 {
686                     if (log)
687                         log->Printf("The interpreter shouldn't have accepted %s", PrintValue(call_inst).c_str());
688                     error.SetErrorToGenericError();
689                     error.SetErrorString(interpreter_internal_error);
690                     return false;
691                 }
692             }
693                 break;
694             case Instruction::Add:
695             case Instruction::Sub:
696             case Instruction::Mul:
697             case Instruction::SDiv:
698             case Instruction::UDiv:
699             case Instruction::SRem:
700             case Instruction::URem:
701             case Instruction::Shl:
702             case Instruction::LShr:
703             case Instruction::AShr:
704             case Instruction::And:
705             case Instruction::Or:
706             case Instruction::Xor:
707             {
708                 const BinaryOperator *bin_op = dyn_cast<BinaryOperator>(inst);
709 
710                 if (!bin_op)
711                 {
712                     if (log)
713                         log->Printf("getOpcode() returns %s, but instruction is not a BinaryOperator", inst->getOpcodeName());
714                     error.SetErrorToGenericError();
715                     error.SetErrorString(interpreter_internal_error);
716                     return false;
717                 }
718 
719                 Value *lhs = inst->getOperand(0);
720                 Value *rhs = inst->getOperand(1);
721 
722                 lldb_private::Scalar L;
723                 lldb_private::Scalar R;
724 
725                 if (!frame.EvaluateValue(L, lhs, module))
726                 {
727                     if (log)
728                         log->Printf("Couldn't evaluate %s", PrintValue(lhs).c_str());
729                     error.SetErrorToGenericError();
730                     error.SetErrorString(bad_value_error);
731                     return false;
732                 }
733 
734                 if (!frame.EvaluateValue(R, rhs, module))
735                 {
736                     if (log)
737                         log->Printf("Couldn't evaluate %s", PrintValue(rhs).c_str());
738                     error.SetErrorToGenericError();
739                     error.SetErrorString(bad_value_error);
740                     return false;
741                 }
742 
743                 lldb_private::Scalar result;
744 
745                 switch (inst->getOpcode())
746                 {
747                     default:
748                         break;
749                     case Instruction::Add:
750                         result = L + R;
751                         break;
752                     case Instruction::Mul:
753                         result = L * R;
754                         break;
755                     case Instruction::Sub:
756                         result = L - R;
757                         break;
758                     case Instruction::SDiv:
759                         L.MakeSigned();
760                         R.MakeSigned();
761                         result = L / R;
762                         break;
763                     case Instruction::UDiv:
764                         result = L.GetRawBits64(0) / R.GetRawBits64(1);
765                         break;
766                     case Instruction::SRem:
767                         L.MakeSigned();
768                         R.MakeSigned();
769                         result = L % R;
770                         break;
771                     case Instruction::URem:
772                         result = L.GetRawBits64(0) % R.GetRawBits64(1);
773                         break;
774                     case Instruction::Shl:
775                         result = L << R;
776                         break;
777                     case Instruction::AShr:
778                         result = L >> R;
779                         break;
780                     case Instruction::LShr:
781                         result = L;
782                         result.ShiftRightLogical(R);
783                         break;
784                     case Instruction::And:
785                         result = L & R;
786                         break;
787                     case Instruction::Or:
788                         result = L | R;
789                         break;
790                     case Instruction::Xor:
791                         result = L ^ R;
792                         break;
793                 }
794 
795                 frame.AssignValue(inst, result, module);
796 
797                 if (log)
798                 {
799                     log->Printf("Interpreted a %s", inst->getOpcodeName());
800                     log->Printf("  L : %s", frame.SummarizeValue(lhs).c_str());
801                     log->Printf("  R : %s", frame.SummarizeValue(rhs).c_str());
802                     log->Printf("  = : %s", frame.SummarizeValue(inst).c_str());
803                 }
804             }
805                 break;
806             case Instruction::Alloca:
807             {
808                 const AllocaInst *alloca_inst = dyn_cast<AllocaInst>(inst);
809 
810                 if (!alloca_inst)
811                 {
812                     if (log)
813                         log->Printf("getOpcode() returns Alloca, but instruction is not an AllocaInst");
814                     error.SetErrorToGenericError();
815                     error.SetErrorString(interpreter_internal_error);
816                     return false;
817                 }
818 
819                 if (alloca_inst->isArrayAllocation())
820                 {
821                     if (log)
822                         log->Printf("AllocaInsts are not handled if isArrayAllocation() is true");
823                     error.SetErrorToGenericError();
824                     error.SetErrorString(unsupported_opcode_error);
825                     return false;
826                 }
827 
828                 // The semantics of Alloca are:
829                 //   Create a region R of virtual memory of type T, backed by a data buffer
830                 //   Create a region P of virtual memory of type T*, backed by a data buffer
831                 //   Write the virtual address of R into P
832 
833                 Type *T = alloca_inst->getAllocatedType();
834                 Type *Tptr = alloca_inst->getType();
835 
836                 lldb::addr_t R = frame.Malloc(T);
837 
838                 if (R == LLDB_INVALID_ADDRESS)
839                 {
840                     if (log)
841                         log->Printf("Couldn't allocate memory for an AllocaInst");
842                     error.SetErrorToGenericError();
843                     error.SetErrorString(memory_allocation_error);
844                     return false;
845                 }
846 
847                 lldb::addr_t P = frame.Malloc(Tptr);
848 
849                 if (P == LLDB_INVALID_ADDRESS)
850                 {
851                     if (log)
852                         log->Printf("Couldn't allocate the result pointer for an AllocaInst");
853                     error.SetErrorToGenericError();
854                     error.SetErrorString(memory_allocation_error);
855                     return false;
856                 }
857 
858                 lldb_private::Error write_error;
859 
860                 memory_map.WritePointerToMemory(P, R, write_error);
861 
862                 if (!write_error.Success())
863                 {
864                     if (log)
865                         log->Printf("Couldn't write the result pointer for an AllocaInst");
866                     error.SetErrorToGenericError();
867                     error.SetErrorString(memory_write_error);
868                     lldb_private::Error free_error;
869                     memory_map.Free(P, free_error);
870                     memory_map.Free(R, free_error);
871                     return false;
872                 }
873 
874                 frame.m_values[alloca_inst] = P;
875 
876                 if (log)
877                 {
878                     log->Printf("Interpreted an AllocaInst");
879                     log->Printf("  R : 0x%" PRIx64, R);
880                     log->Printf("  P : 0x%" PRIx64, P);
881                 }
882             }
883                 break;
884             case Instruction::BitCast:
885             case Instruction::ZExt:
886             {
887                 const CastInst *cast_inst = dyn_cast<CastInst>(inst);
888 
889                 if (!cast_inst)
890                 {
891                     if (log)
892                         log->Printf("getOpcode() returns %s, but instruction is not a BitCastInst", cast_inst->getOpcodeName());
893                     error.SetErrorToGenericError();
894                     error.SetErrorString(interpreter_internal_error);
895                     return false;
896                 }
897 
898                 Value *source = cast_inst->getOperand(0);
899 
900                 lldb_private::Scalar S;
901 
902                 if (!frame.EvaluateValue(S, source, module))
903                 {
904                     if (log)
905                         log->Printf("Couldn't evaluate %s", PrintValue(source).c_str());
906                     error.SetErrorToGenericError();
907                     error.SetErrorString(bad_value_error);
908                     return false;
909                 }
910 
911                 frame.AssignValue(inst, S, module);
912             }
913                 break;
914             case Instruction::SExt:
915             {
916                 const CastInst *cast_inst = dyn_cast<CastInst>(inst);
917 
918                 if (!cast_inst)
919                 {
920                     if (log)
921                         log->Printf("getOpcode() returns %s, but instruction is not a BitCastInst", cast_inst->getOpcodeName());
922                     error.SetErrorToGenericError();
923                     error.SetErrorString(interpreter_internal_error);
924                     return false;
925                 }
926 
927                 Value *source = cast_inst->getOperand(0);
928 
929                 lldb_private::Scalar S;
930 
931                 if (!frame.EvaluateValue(S, source, module))
932                 {
933                     if (log)
934                         log->Printf("Couldn't evaluate %s", PrintValue(source).c_str());
935                     error.SetErrorToGenericError();
936                     error.SetErrorString(bad_value_error);
937                     return false;
938                 }
939 
940                 S.MakeSigned();
941 
942                 lldb_private::Scalar S_signextend(S.SLongLong());
943 
944                 frame.AssignValue(inst, S_signextend, module);
945             }
946                 break;
947             case Instruction::Br:
948             {
949                 const BranchInst *br_inst = dyn_cast<BranchInst>(inst);
950 
951                 if (!br_inst)
952                 {
953                     if (log)
954                         log->Printf("getOpcode() returns Br, but instruction is not a BranchInst");
955                     error.SetErrorToGenericError();
956                     error.SetErrorString(interpreter_internal_error);
957                     return false;
958                 }
959 
960                 if (br_inst->isConditional())
961                 {
962                     Value *condition = br_inst->getCondition();
963 
964                     lldb_private::Scalar C;
965 
966                     if (!frame.EvaluateValue(C, condition, module))
967                     {
968                         if (log)
969                             log->Printf("Couldn't evaluate %s", PrintValue(condition).c_str());
970                         error.SetErrorToGenericError();
971                         error.SetErrorString(bad_value_error);
972                         return false;
973                     }
974 
975                     if (C.GetRawBits64(0))
976                         frame.Jump(br_inst->getSuccessor(0));
977                     else
978                         frame.Jump(br_inst->getSuccessor(1));
979 
980                     if (log)
981                     {
982                         log->Printf("Interpreted a BrInst with a condition");
983                         log->Printf("  cond : %s", frame.SummarizeValue(condition).c_str());
984                     }
985                 }
986                 else
987                 {
988                     frame.Jump(br_inst->getSuccessor(0));
989 
990                     if (log)
991                     {
992                         log->Printf("Interpreted a BrInst with no condition");
993                     }
994                 }
995             }
996                 continue;
997             case Instruction::GetElementPtr:
998             {
999                 const GetElementPtrInst *gep_inst = dyn_cast<GetElementPtrInst>(inst);
1000 
1001                 if (!gep_inst)
1002                 {
1003                     if (log)
1004                         log->Printf("getOpcode() returns GetElementPtr, but instruction is not a GetElementPtrInst");
1005                     error.SetErrorToGenericError();
1006                     error.SetErrorString(interpreter_internal_error);
1007                     return false;
1008                 }
1009 
1010                 const Value *pointer_operand = gep_inst->getPointerOperand();
1011                 Type *pointer_type = pointer_operand->getType();
1012 
1013                 lldb_private::Scalar P;
1014 
1015                 if (!frame.EvaluateValue(P, pointer_operand, module))
1016                 {
1017                     if (log)
1018                         log->Printf("Couldn't evaluate %s", PrintValue(pointer_operand).c_str());
1019                     error.SetErrorToGenericError();
1020                     error.SetErrorString(bad_value_error);
1021                     return false;
1022                 }
1023 
1024                 typedef SmallVector <Value *, 8> IndexVector;
1025                 typedef IndexVector::iterator IndexIterator;
1026 
1027                 SmallVector <Value *, 8> indices (gep_inst->idx_begin(),
1028                                                   gep_inst->idx_end());
1029 
1030                 SmallVector <Value *, 8> const_indices;
1031 
1032                 for (IndexIterator ii = indices.begin(), ie = indices.end();
1033                      ii != ie;
1034                      ++ii)
1035                 {
1036                     ConstantInt *constant_index = dyn_cast<ConstantInt>(*ii);
1037 
1038                     if (!constant_index)
1039                     {
1040                         lldb_private::Scalar I;
1041 
1042                         if (!frame.EvaluateValue(I, *ii, module))
1043                         {
1044                             if (log)
1045                                 log->Printf("Couldn't evaluate %s", PrintValue(*ii).c_str());
1046                             error.SetErrorToGenericError();
1047                             error.SetErrorString(bad_value_error);
1048                             return false;
1049                         }
1050 
1051                         if (log)
1052                             log->Printf("Evaluated constant index %s as %llu", PrintValue(*ii).c_str(), I.ULongLong(LLDB_INVALID_ADDRESS));
1053 
1054                         constant_index = cast<ConstantInt>(ConstantInt::get((*ii)->getType(), I.ULongLong(LLDB_INVALID_ADDRESS)));
1055                     }
1056 
1057                     const_indices.push_back(constant_index);
1058                 }
1059 
1060                 uint64_t offset = data_layout.getIndexedOffset(pointer_type, const_indices);
1061 
1062                 lldb_private::Scalar Poffset = P + offset;
1063 
1064                 frame.AssignValue(inst, Poffset, module);
1065 
1066                 if (log)
1067                 {
1068                     log->Printf("Interpreted a GetElementPtrInst");
1069                     log->Printf("  P       : %s", frame.SummarizeValue(pointer_operand).c_str());
1070                     log->Printf("  Poffset : %s", frame.SummarizeValue(inst).c_str());
1071                 }
1072             }
1073                 break;
1074             case Instruction::ICmp:
1075             {
1076                 const ICmpInst *icmp_inst = dyn_cast<ICmpInst>(inst);
1077 
1078                 if (!icmp_inst)
1079                 {
1080                     if (log)
1081                         log->Printf("getOpcode() returns ICmp, but instruction is not an ICmpInst");
1082                     error.SetErrorToGenericError();
1083                     error.SetErrorString(interpreter_internal_error);
1084                     return false;
1085                 }
1086 
1087                 CmpInst::Predicate predicate = icmp_inst->getPredicate();
1088 
1089                 Value *lhs = inst->getOperand(0);
1090                 Value *rhs = inst->getOperand(1);
1091 
1092                 lldb_private::Scalar L;
1093                 lldb_private::Scalar R;
1094 
1095                 if (!frame.EvaluateValue(L, lhs, module))
1096                 {
1097                     if (log)
1098                         log->Printf("Couldn't evaluate %s", PrintValue(lhs).c_str());
1099                     error.SetErrorToGenericError();
1100                     error.SetErrorString(bad_value_error);
1101                     return false;
1102                 }
1103 
1104                 if (!frame.EvaluateValue(R, rhs, module))
1105                 {
1106                     if (log)
1107                         log->Printf("Couldn't evaluate %s", PrintValue(rhs).c_str());
1108                     error.SetErrorToGenericError();
1109                     error.SetErrorString(bad_value_error);
1110                     return false;
1111                 }
1112 
1113                 lldb_private::Scalar result;
1114 
1115                 switch (predicate)
1116                 {
1117                     default:
1118                         return false;
1119                     case CmpInst::ICMP_EQ:
1120                         result = (L == R);
1121                         break;
1122                     case CmpInst::ICMP_NE:
1123                         result = (L != R);
1124                         break;
1125                     case CmpInst::ICMP_UGT:
1126                         result = (L.GetRawBits64(0) > R.GetRawBits64(0));
1127                         break;
1128                     case CmpInst::ICMP_UGE:
1129                         result = (L.GetRawBits64(0) >= R.GetRawBits64(0));
1130                         break;
1131                     case CmpInst::ICMP_ULT:
1132                         result = (L.GetRawBits64(0) < R.GetRawBits64(0));
1133                         break;
1134                     case CmpInst::ICMP_ULE:
1135                         result = (L.GetRawBits64(0) <= R.GetRawBits64(0));
1136                         break;
1137                     case CmpInst::ICMP_SGT:
1138                         L.MakeSigned();
1139                         R.MakeSigned();
1140                         result = (L > R);
1141                         break;
1142                     case CmpInst::ICMP_SGE:
1143                         L.MakeSigned();
1144                         R.MakeSigned();
1145                         result = (L >= R);
1146                         break;
1147                     case CmpInst::ICMP_SLT:
1148                         L.MakeSigned();
1149                         R.MakeSigned();
1150                         result = (L < R);
1151                         break;
1152                     case CmpInst::ICMP_SLE:
1153                         L.MakeSigned();
1154                         R.MakeSigned();
1155                         result = (L <= R);
1156                         break;
1157                 }
1158 
1159                 frame.AssignValue(inst, result, module);
1160 
1161                 if (log)
1162                 {
1163                     log->Printf("Interpreted an ICmpInst");
1164                     log->Printf("  L : %s", frame.SummarizeValue(lhs).c_str());
1165                     log->Printf("  R : %s", frame.SummarizeValue(rhs).c_str());
1166                     log->Printf("  = : %s", frame.SummarizeValue(inst).c_str());
1167                 }
1168             }
1169                 break;
1170             case Instruction::IntToPtr:
1171             {
1172                 const IntToPtrInst *int_to_ptr_inst = dyn_cast<IntToPtrInst>(inst);
1173 
1174                 if (!int_to_ptr_inst)
1175                 {
1176                     if (log)
1177                         log->Printf("getOpcode() returns IntToPtr, but instruction is not an IntToPtrInst");
1178                     error.SetErrorToGenericError();
1179                     error.SetErrorString(interpreter_internal_error);
1180                     return false;
1181                 }
1182 
1183                 Value *src_operand = int_to_ptr_inst->getOperand(0);
1184 
1185                 lldb_private::Scalar I;
1186 
1187                 if (!frame.EvaluateValue(I, src_operand, module))
1188                 {
1189                     if (log)
1190                         log->Printf("Couldn't evaluate %s", PrintValue(src_operand).c_str());
1191                     error.SetErrorToGenericError();
1192                     error.SetErrorString(bad_value_error);
1193                     return false;
1194                 }
1195 
1196                 frame.AssignValue(inst, I, module);
1197 
1198                 if (log)
1199                 {
1200                     log->Printf("Interpreted an IntToPtr");
1201                     log->Printf("  Src : %s", frame.SummarizeValue(src_operand).c_str());
1202                     log->Printf("  =   : %s", frame.SummarizeValue(inst).c_str());
1203                 }
1204             }
1205                 break;
1206             case Instruction::PtrToInt:
1207             {
1208                 const PtrToIntInst *ptr_to_int_inst = dyn_cast<PtrToIntInst>(inst);
1209 
1210                 if (!ptr_to_int_inst)
1211                 {
1212                     if (log)
1213                         log->Printf("getOpcode() returns PtrToInt, but instruction is not an PtrToIntInst");
1214                     error.SetErrorToGenericError();
1215                     error.SetErrorString(interpreter_internal_error);
1216                     return false;
1217                 }
1218 
1219                 Value *src_operand = ptr_to_int_inst->getOperand(0);
1220 
1221                 lldb_private::Scalar I;
1222 
1223                 if (!frame.EvaluateValue(I, src_operand, module))
1224                 {
1225                     if (log)
1226                         log->Printf("Couldn't evaluate %s", PrintValue(src_operand).c_str());
1227                     error.SetErrorToGenericError();
1228                     error.SetErrorString(bad_value_error);
1229                     return false;
1230                 }
1231 
1232                 frame.AssignValue(inst, I, module);
1233 
1234                 if (log)
1235                 {
1236                     log->Printf("Interpreted a PtrToInt");
1237                     log->Printf("  Src : %s", frame.SummarizeValue(src_operand).c_str());
1238                     log->Printf("  =   : %s", frame.SummarizeValue(inst).c_str());
1239                 }
1240             }
1241                 break;
1242             case Instruction::Trunc:
1243             {
1244                 const TruncInst *trunc_inst = dyn_cast<TruncInst>(inst);
1245 
1246                 if (!trunc_inst)
1247                 {
1248                     if (log)
1249                         log->Printf("getOpcode() returns Trunc, but instruction is not a TruncInst");
1250                     error.SetErrorToGenericError();
1251                     error.SetErrorString(interpreter_internal_error);
1252                     return false;
1253                 }
1254 
1255                 Value *src_operand = trunc_inst->getOperand(0);
1256 
1257                 lldb_private::Scalar I;
1258 
1259                 if (!frame.EvaluateValue(I, src_operand, module))
1260                 {
1261                     if (log)
1262                         log->Printf("Couldn't evaluate %s", PrintValue(src_operand).c_str());
1263                     error.SetErrorToGenericError();
1264                     error.SetErrorString(bad_value_error);
1265                     return false;
1266                 }
1267 
1268                 frame.AssignValue(inst, I, module);
1269 
1270                 if (log)
1271                 {
1272                     log->Printf("Interpreted a Trunc");
1273                     log->Printf("  Src : %s", frame.SummarizeValue(src_operand).c_str());
1274                     log->Printf("  =   : %s", frame.SummarizeValue(inst).c_str());
1275                 }
1276             }
1277                 break;
1278             case Instruction::Load:
1279             {
1280                 const LoadInst *load_inst = dyn_cast<LoadInst>(inst);
1281 
1282                 if (!load_inst)
1283                 {
1284                     if (log)
1285                         log->Printf("getOpcode() returns Load, but instruction is not a LoadInst");
1286                     error.SetErrorToGenericError();
1287                     error.SetErrorString(interpreter_internal_error);
1288                     return false;
1289                 }
1290 
1291                 // The semantics of Load are:
1292                 //   Create a region D that will contain the loaded data
1293                 //   Resolve the region P containing a pointer
1294                 //   Dereference P to get the region R that the data should be loaded from
1295                 //   Transfer a unit of type type(D) from R to D
1296 
1297                 const Value *pointer_operand = load_inst->getPointerOperand();
1298 
1299                 Type *pointer_ty = pointer_operand->getType();
1300                 PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
1301                 if (!pointer_ptr_ty)
1302                 {
1303                     if (log)
1304                         log->Printf("getPointerOperand()->getType() is not a PointerType");
1305                     error.SetErrorToGenericError();
1306                     error.SetErrorString(interpreter_internal_error);
1307                     return false;
1308                 }
1309                 Type *target_ty = pointer_ptr_ty->getElementType();
1310 
1311                 lldb::addr_t D = frame.ResolveValue(load_inst, module);
1312                 lldb::addr_t P = frame.ResolveValue(pointer_operand, module);
1313 
1314                 if (D == LLDB_INVALID_ADDRESS)
1315                 {
1316                     if (log)
1317                         log->Printf("LoadInst's value doesn't resolve to anything");
1318                     error.SetErrorToGenericError();
1319                     error.SetErrorString(bad_value_error);
1320                     return false;
1321                 }
1322 
1323                 if (P == LLDB_INVALID_ADDRESS)
1324                 {
1325                     if (log)
1326                         log->Printf("LoadInst's pointer doesn't resolve to anything");
1327                     error.SetErrorToGenericError();
1328                     error.SetErrorString(bad_value_error);
1329                     return false;
1330                 }
1331 
1332                 lldb::addr_t R;
1333                 lldb_private::Error read_error;
1334                 memory_map.ReadPointerFromMemory(&R, P, read_error);
1335 
1336                 if (!read_error.Success())
1337                 {
1338                     if (log)
1339                         log->Printf("Couldn't read the address to be loaded for a LoadInst");
1340                     error.SetErrorToGenericError();
1341                     error.SetErrorString(memory_read_error);
1342                     return false;
1343                 }
1344 
1345                 size_t target_size = data_layout.getTypeStoreSize(target_ty);
1346                 lldb_private::DataBufferHeap buffer(target_size, 0);
1347 
1348                 read_error.Clear();
1349                 memory_map.ReadMemory(buffer.GetBytes(), R, buffer.GetByteSize(), read_error);
1350                 if (!read_error.Success())
1351                 {
1352                     if (log)
1353                         log->Printf("Couldn't read from a region on behalf of a LoadInst");
1354                     error.SetErrorToGenericError();
1355                     error.SetErrorString(memory_read_error);
1356                     return false;
1357                 }
1358 
1359                 lldb_private::Error write_error;
1360                 memory_map.WriteMemory(D, buffer.GetBytes(), buffer.GetByteSize(), write_error);
1361                 if (!write_error.Success())
1362                 {
1363                     if (log)
1364                         log->Printf("Couldn't write to a region on behalf of a LoadInst");
1365                     error.SetErrorToGenericError();
1366                     error.SetErrorString(memory_read_error);
1367                     return false;
1368                 }
1369 
1370                 if (log)
1371                 {
1372                     log->Printf("Interpreted a LoadInst");
1373                     log->Printf("  P : 0x%" PRIx64, P);
1374                     log->Printf("  R : 0x%" PRIx64, R);
1375                     log->Printf("  D : 0x%" PRIx64, D);
1376                 }
1377             }
1378                 break;
1379             case Instruction::Ret:
1380             {
1381                 return true;
1382             }
1383             case Instruction::Store:
1384             {
1385                 const StoreInst *store_inst = dyn_cast<StoreInst>(inst);
1386 
1387                 if (!store_inst)
1388                 {
1389                     if (log)
1390                         log->Printf("getOpcode() returns Store, but instruction is not a StoreInst");
1391                     error.SetErrorToGenericError();
1392                     error.SetErrorString(interpreter_internal_error);
1393                     return false;
1394                 }
1395 
1396                 // The semantics of Store are:
1397                 //   Resolve the region D containing the data to be stored
1398                 //   Resolve the region P containing a pointer
1399                 //   Dereference P to get the region R that the data should be stored in
1400                 //   Transfer a unit of type type(D) from D to R
1401 
1402                 const Value *value_operand = store_inst->getValueOperand();
1403                 const Value *pointer_operand = store_inst->getPointerOperand();
1404 
1405                 Type *pointer_ty = pointer_operand->getType();
1406                 PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
1407                 if (!pointer_ptr_ty)
1408                     return false;
1409                 Type *target_ty = pointer_ptr_ty->getElementType();
1410 
1411                 lldb::addr_t D = frame.ResolveValue(value_operand, module);
1412                 lldb::addr_t P = frame.ResolveValue(pointer_operand, module);
1413 
1414                 if (D == LLDB_INVALID_ADDRESS)
1415                 {
1416                     if (log)
1417                         log->Printf("StoreInst's value doesn't resolve to anything");
1418                     error.SetErrorToGenericError();
1419                     error.SetErrorString(bad_value_error);
1420                     return false;
1421                 }
1422 
1423                 if (P == LLDB_INVALID_ADDRESS)
1424                 {
1425                     if (log)
1426                         log->Printf("StoreInst's pointer doesn't resolve to anything");
1427                     error.SetErrorToGenericError();
1428                     error.SetErrorString(bad_value_error);
1429                     return false;
1430                 }
1431 
1432                 lldb::addr_t R;
1433                 lldb_private::Error read_error;
1434                 memory_map.ReadPointerFromMemory(&R, P, read_error);
1435 
1436                 if (!read_error.Success())
1437                 {
1438                     if (log)
1439                         log->Printf("Couldn't read the address to be loaded for a LoadInst");
1440                     error.SetErrorToGenericError();
1441                     error.SetErrorString(memory_read_error);
1442                     return false;
1443                 }
1444 
1445                 size_t target_size = data_layout.getTypeStoreSize(target_ty);
1446                 lldb_private::DataBufferHeap buffer(target_size, 0);
1447 
1448                 read_error.Clear();
1449                 memory_map.ReadMemory(buffer.GetBytes(), D, buffer.GetByteSize(), read_error);
1450                 if (!read_error.Success())
1451                 {
1452                     if (log)
1453                         log->Printf("Couldn't read from a region on behalf of a StoreInst");
1454                     error.SetErrorToGenericError();
1455                     error.SetErrorString(memory_read_error);
1456                     return false;
1457                 }
1458 
1459                 lldb_private::Error write_error;
1460                 memory_map.WriteMemory(R, buffer.GetBytes(), buffer.GetByteSize(), write_error);
1461                 if (!write_error.Success())
1462                 {
1463                     if (log)
1464                         log->Printf("Couldn't write to a region on behalf of a StoreInst");
1465                     error.SetErrorToGenericError();
1466                     error.SetErrorString(memory_write_error);
1467                     return false;
1468                 }
1469 
1470                 if (log)
1471                 {
1472                     log->Printf("Interpreted a StoreInst");
1473                     log->Printf("  D : 0x%" PRIx64, D);
1474                     log->Printf("  P : 0x%" PRIx64, P);
1475                     log->Printf("  R : 0x%" PRIx64, R);
1476                 }
1477             }
1478                 break;
1479         }
1480 
1481         ++frame.m_ii;
1482     }
1483 
1484     if (num_insts >= 4096)
1485     {
1486         error.SetErrorToGenericError();
1487         error.SetErrorString(infinite_loop_error);
1488         return false;
1489     }
1490 
1491     return false;
1492 }
1493