1 //===-- ABISysV_riscv.cpp ------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===---------------------------------------------------------------------===//
8 
9 #include "ABISysV_riscv.h"
10 
11 #include <array>
12 #include <limits>
13 
14 #include "llvm/IR/DerivedTypes.h"
15 
16 #include "lldb/Core/PluginManager.h"
17 #include "lldb/Core/Value.h"
18 #include "lldb/Core/ValueObjectConstResult.h"
19 #include "lldb/Target/RegisterContext.h"
20 #include "lldb/Target/StackFrame.h"
21 #include "lldb/Target/Thread.h"
22 #include "lldb/Utility/RegisterValue.h"
23 
24 #define DEFINE_REG_NAME(reg_num) ConstString(#reg_num).GetCString()
25 #define DEFINE_REG_NAME_STR(reg_name) ConstString(reg_name).GetCString()
26 
27 // The ABI is not a source of such information as size, offset, encoding, etc.
28 // of a register. Just provides correct dwarf and eh_frame numbers.
29 
30 #define DEFINE_GENERIC_REGISTER_STUB(dwarf_num, str_name, generic_num)         \
31   {                                                                            \
32     DEFINE_REG_NAME(dwarf_num), DEFINE_REG_NAME_STR(str_name), 0, 0,           \
33         eEncodingInvalid, eFormatDefault,                                      \
34         {dwarf_num, dwarf_num, generic_num, LLDB_INVALID_REGNUM, dwarf_num},   \
35         nullptr, nullptr, nullptr,                                             \
36   }
37 
38 #define DEFINE_REGISTER_STUB(dwarf_num, str_name)                              \
39   DEFINE_GENERIC_REGISTER_STUB(dwarf_num, str_name, LLDB_INVALID_REGNUM)
40 
41 using namespace lldb;
42 using namespace lldb_private;
43 
44 LLDB_PLUGIN_DEFINE_ADV(ABISysV_riscv, ABIRISCV)
45 
46 namespace {
47 namespace dwarf {
48 enum regnums {
49   zero,
50   ra,
51   sp,
52   gp,
53   tp,
54   t0,
55   t1,
56   t2,
57   fp,
58   s0 = fp,
59   s1,
60   a0,
61   a1,
62   a2,
63   a3,
64   a4,
65   a5,
66   a6,
67   a7,
68   s2,
69   s3,
70   s4,
71   s5,
72   s6,
73   s7,
74   s8,
75   s9,
76   s10,
77   s11,
78   t3,
79   t4,
80   t5,
81   t6,
82   pc
83 };
84 
85 static const std::array<RegisterInfo, 33> g_register_infos = {
86     {DEFINE_REGISTER_STUB(zero, nullptr),
87      DEFINE_GENERIC_REGISTER_STUB(ra, nullptr, LLDB_REGNUM_GENERIC_RA),
88      DEFINE_GENERIC_REGISTER_STUB(sp, nullptr, LLDB_REGNUM_GENERIC_SP),
89      DEFINE_REGISTER_STUB(gp, nullptr),
90      DEFINE_REGISTER_STUB(tp, nullptr),
91      DEFINE_REGISTER_STUB(t0, nullptr),
92      DEFINE_REGISTER_STUB(t1, nullptr),
93      DEFINE_REGISTER_STUB(t2, nullptr),
94      DEFINE_GENERIC_REGISTER_STUB(fp, nullptr, LLDB_REGNUM_GENERIC_FP),
95      DEFINE_REGISTER_STUB(s1, nullptr),
96      DEFINE_GENERIC_REGISTER_STUB(a0, nullptr, LLDB_REGNUM_GENERIC_ARG1),
97      DEFINE_GENERIC_REGISTER_STUB(a1, nullptr, LLDB_REGNUM_GENERIC_ARG2),
98      DEFINE_GENERIC_REGISTER_STUB(a2, nullptr, LLDB_REGNUM_GENERIC_ARG3),
99      DEFINE_GENERIC_REGISTER_STUB(a3, nullptr, LLDB_REGNUM_GENERIC_ARG4),
100      DEFINE_GENERIC_REGISTER_STUB(a4, nullptr, LLDB_REGNUM_GENERIC_ARG5),
101      DEFINE_GENERIC_REGISTER_STUB(a5, nullptr, LLDB_REGNUM_GENERIC_ARG6),
102      DEFINE_GENERIC_REGISTER_STUB(a6, nullptr, LLDB_REGNUM_GENERIC_ARG7),
103      DEFINE_GENERIC_REGISTER_STUB(a7, nullptr, LLDB_REGNUM_GENERIC_ARG8),
104      DEFINE_REGISTER_STUB(s2, nullptr),
105      DEFINE_REGISTER_STUB(s3, nullptr),
106      DEFINE_REGISTER_STUB(s4, nullptr),
107      DEFINE_REGISTER_STUB(s5, nullptr),
108      DEFINE_REGISTER_STUB(s6, nullptr),
109      DEFINE_REGISTER_STUB(s7, nullptr),
110      DEFINE_REGISTER_STUB(s8, nullptr),
111      DEFINE_REGISTER_STUB(s9, nullptr),
112      DEFINE_REGISTER_STUB(s10, nullptr),
113      DEFINE_REGISTER_STUB(s11, nullptr),
114      DEFINE_REGISTER_STUB(t3, nullptr),
115      DEFINE_REGISTER_STUB(t4, nullptr),
116      DEFINE_REGISTER_STUB(t5, nullptr),
117      DEFINE_REGISTER_STUB(t6, nullptr),
118      DEFINE_GENERIC_REGISTER_STUB(pc, nullptr, LLDB_REGNUM_GENERIC_PC)}};
119 } // namespace dwarf
120 } // namespace
121 
122 const RegisterInfo *ABISysV_riscv::GetRegisterInfoArray(uint32_t &count) {
123   count = dwarf::g_register_infos.size();
124   return dwarf::g_register_infos.data();
125 }
126 
127 //------------------------------------------------------------------
128 // Static Functions
129 //------------------------------------------------------------------
130 
131 ABISP
132 ABISysV_riscv::CreateInstance(ProcessSP process_sp, const ArchSpec &arch) {
133   llvm::Triple::ArchType machine = arch.GetTriple().getArch();
134 
135   if (llvm::Triple::riscv32 != machine && llvm::Triple::riscv64 != machine)
136     return ABISP();
137 
138   ABISysV_riscv *abi = new ABISysV_riscv(std::move(process_sp),
139                                          MakeMCRegisterInfo(arch));
140   if (abi)
141     abi->SetIsRV64((llvm::Triple::riscv64 == machine) ? true : false);
142   return ABISP(abi);
143 }
144 
145 static inline size_t AugmentArgSize(bool is_rv64, size_t size_in_bytes) {
146   size_t word_size = is_rv64 ? 8 : 4;
147   return llvm::alignTo(size_in_bytes, word_size);
148 }
149 
150 static size_t
151 TotalArgsSizeInWords(bool is_rv64,
152                      const llvm::ArrayRef<ABI::CallArgument> &args) {
153   size_t reg_size = is_rv64 ? 8 : 4;
154   size_t word_size = reg_size;
155   size_t total_size = 0;
156   for (const auto &arg : args)
157     total_size +=
158         (ABI::CallArgument::TargetValue == arg.type ? AugmentArgSize(is_rv64,
159                                                                      arg.size)
160                                                     : reg_size) /
161         word_size;
162 
163   return total_size;
164 }
165 
166 bool ABISysV_riscv::PrepareTrivialCall(Thread &thread, addr_t sp,
167                                        addr_t func_addr, addr_t return_addr,
168                                        llvm::ArrayRef<addr_t> args) const {
169   // TODO: Implement
170   return false;
171 }
172 
173 bool ABISysV_riscv::PrepareTrivialCall(
174     Thread &thread, addr_t sp, addr_t pc, addr_t ra, llvm::Type &prototype,
175     llvm::ArrayRef<ABI::CallArgument> args) const {
176   auto reg_ctx = thread.GetRegisterContext();
177   if (!reg_ctx)
178     return false;
179 
180   uint32_t pc_reg = reg_ctx->ConvertRegisterKindToRegisterNumber(
181       eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
182   if (pc_reg == LLDB_INVALID_REGNUM)
183     return false;
184 
185   uint32_t ra_reg = reg_ctx->ConvertRegisterKindToRegisterNumber(
186       eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA);
187   if (ra_reg == LLDB_INVALID_REGNUM)
188     return false;
189 
190   uint32_t sp_reg = reg_ctx->ConvertRegisterKindToRegisterNumber(
191       eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
192   if (sp_reg == LLDB_INVALID_REGNUM)
193     return false;
194 
195   Status error;
196   ProcessSP process = thread.GetProcess();
197   if (!process)
198     return false;
199 
200   size_t reg_size = m_is_rv64 ? 8 : 4;
201   size_t word_size = reg_size;
202   // Push host data onto target.
203   for (const auto &arg : args) {
204     // Skip over target values.
205     if (arg.type == ABI::CallArgument::TargetValue)
206       continue;
207 
208     // Create space on the host stack for this data 4-byte aligned.
209     sp -= AugmentArgSize(m_is_rv64, arg.size);
210 
211     if (process->WriteMemory(sp, arg.data_up.get(), arg.size, error) <
212             arg.size ||
213         error.Fail())
214       return false;
215 
216     // Update the argument with the target pointer.
217     *const_cast<addr_t *>(&arg.value) = sp;
218   }
219 
220   // Make sure number of parameters matches prototype.
221   assert(prototype.getFunctionNumParams() == args.size());
222 
223   const size_t num_args = args.size();
224   const size_t regs_for_args_count = 8U;
225   const size_t num_args_in_regs =
226       num_args > regs_for_args_count ?  regs_for_args_count : num_args;
227 
228   // Number of arguments passed on stack.
229   size_t args_size = TotalArgsSizeInWords(m_is_rv64, args);
230   auto on_stack =
231       args_size <= regs_for_args_count ? 0 : args_size - regs_for_args_count;
232   auto offset = on_stack * word_size;
233 
234   uint8_t reg_value[8];
235   size_t reg_index = LLDB_REGNUM_GENERIC_ARG1;
236 
237   for (size_t i = 0; i < args_size; ++i) {
238     auto value = reinterpret_cast<const uint8_t *>(&args[i].value);
239     auto size =
240         ABI::CallArgument::TargetValue == args[i].type ? args[i].size : reg_size;
241 
242     // Pass arguments via registers.
243     if (i < num_args_in_regs) {
244       // copy value to register, padding if arg is smaller than register
245       auto end = size < reg_size ? size : reg_size;
246       memcpy(reg_value, value, end);
247       if (reg_size > end)
248         memset(reg_value + end, 0, reg_size - end);
249 
250       RegisterValue reg_val_obj(llvm::ArrayRef(reg_value, reg_size),
251                                 eByteOrderLittle);
252       if (!reg_ctx->WriteRegister(
253               reg_ctx->GetRegisterInfo(eRegisterKindGeneric, reg_index),
254               reg_val_obj))
255         return false;
256 
257       // NOTE: It's unsafe to iterate through LLDB_REGNUM_GENERICs
258       // But the "a" registers are sequential in the RISC-V register space
259       ++reg_index;
260     }
261 
262     if (reg_index < regs_for_args_count || size == 0)
263       continue;
264 
265     // Remaining arguments are passed on the stack.
266     if (process->WriteMemory(sp - offset, value, size, error) < size ||
267         !error.Success())
268       return false;
269 
270     offset -= AugmentArgSize(m_is_rv64, size);
271   }
272 
273   // Set stack pointer immediately below arguments.
274   sp -= on_stack * word_size;
275 
276   // Update registers with current function call state.
277   reg_ctx->WriteRegisterFromUnsigned(pc_reg, pc);
278   reg_ctx->WriteRegisterFromUnsigned(ra_reg, ra);
279   reg_ctx->WriteRegisterFromUnsigned(sp_reg, sp);
280 
281   return true;
282 }
283 
284 bool ABISysV_riscv::GetArgumentValues(Thread &thread, ValueList &values) const {
285   // TODO: Implement
286   return false;
287 }
288 
289 Status ABISysV_riscv::SetReturnValueObject(StackFrameSP &frame_sp,
290                                            ValueObjectSP &new_value_sp) {
291   Status result;
292   if (!new_value_sp) {
293     result.SetErrorString("Empty value object for return value.");
294     return result;
295   }
296 
297   CompilerType compiler_type = new_value_sp->GetCompilerType();
298   if (!compiler_type) {
299     result.SetErrorString("Null clang type for return value.");
300     return result;
301   }
302 
303   auto &reg_ctx = *frame_sp->GetThread()->GetRegisterContext();
304 
305   bool is_signed = false;
306   if (!compiler_type.IsIntegerOrEnumerationType(is_signed) &&
307       !compiler_type.IsPointerType()) {
308     result.SetErrorString("We don't support returning other types at present");
309     return result;
310   }
311 
312   DataExtractor data;
313   size_t num_bytes = new_value_sp->GetData(data, result);
314 
315   if (result.Fail()) {
316     result.SetErrorStringWithFormat(
317         "Couldn't convert return value to raw data: %s", result.AsCString());
318     return result;
319   }
320 
321   size_t reg_size = m_is_rv64 ? 8 : 4;
322   if (num_bytes <= 2 * reg_size) {
323     offset_t offset = 0;
324     uint64_t raw_value = data.GetMaxU64(&offset, num_bytes);
325 
326     auto reg_info =
327         reg_ctx.GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1);
328     if (!reg_ctx.WriteRegisterFromUnsigned(reg_info, raw_value)) {
329       result.SetErrorStringWithFormat("Couldn't write value to register %s",
330                                       reg_info->name);
331       return result;
332     }
333 
334     if (num_bytes <= reg_size)
335       return result; // Successfully written.
336 
337     // for riscv32, get the upper 32 bits from raw_value and write them
338     // for riscv64, get the next 64 bits from data and write them
339     if (4 == reg_size)
340       raw_value >>= 32;
341     else
342       raw_value = data.GetMaxU64(&offset, num_bytes - reg_size);
343     reg_info =
344         reg_ctx.GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG2);
345     if (!reg_ctx.WriteRegisterFromUnsigned(reg_info, raw_value)) {
346       result.SetErrorStringWithFormat("Couldn't write value to register %s",
347                                       reg_info->name);
348     }
349 
350     return result;
351   }
352 
353   result.SetErrorString(
354       "We don't support returning large integer values at present.");
355   return result;
356 }
357 
358 template <typename T>
359 static void SetInteger(Scalar &scalar, uint64_t raw_value, bool is_signed) {
360   raw_value &= std::numeric_limits<T>::max();
361   if (is_signed)
362     scalar = static_cast<typename std::make_signed<T>::type>(raw_value);
363   else
364     scalar = static_cast<T>(raw_value);
365 }
366 
367 static bool SetSizedInteger(Scalar &scalar, uint64_t raw_value,
368                             uint8_t size_in_bytes, bool is_signed) {
369   switch (size_in_bytes) {
370   default:
371     return false;
372 
373   case sizeof(uint64_t):
374     SetInteger<uint64_t>(scalar, raw_value, is_signed);
375     break;
376 
377   case sizeof(uint32_t):
378     SetInteger<uint32_t>(scalar, raw_value, is_signed);
379     break;
380 
381   case sizeof(uint16_t):
382     SetInteger<uint16_t>(scalar, raw_value, is_signed);
383     break;
384 
385   case sizeof(uint8_t):
386     SetInteger<uint8_t>(scalar, raw_value, is_signed);
387     break;
388   }
389 
390   return true;
391 }
392 
393 static bool SetSizedFloat(Scalar &scalar, uint64_t raw_value,
394                           uint8_t size_in_bytes) {
395   switch (size_in_bytes) {
396   default:
397     return false;
398 
399   case sizeof(uint64_t):
400     scalar = *reinterpret_cast<double *>(&raw_value);
401     break;
402 
403   case sizeof(uint32_t):
404     scalar = *reinterpret_cast<float *>(&raw_value);
405     break;
406   }
407 
408   return true;
409 }
410 
411 static ValueObjectSP GetValObjFromIntRegs(Thread &thread,
412                                           const RegisterContextSP &reg_ctx,
413                                           llvm::Triple::ArchType machine,
414                                           uint32_t type_flags,
415                                           uint32_t byte_size) {
416   Value value;
417   ValueObjectSP return_valobj_sp;
418   auto reg_info_a0 =
419       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1);
420   auto reg_info_a1 =
421       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG2);
422   uint64_t raw_value;
423 
424   switch (byte_size) {
425   case sizeof(uint32_t):
426     // Read a0 to get the arg
427     raw_value = reg_ctx->ReadRegisterAsUnsigned(reg_info_a0, 0) & UINT32_MAX;
428     break;
429   case sizeof(uint64_t):
430     // Read a0 to get the arg on riscv64, a0 and a1 on riscv32
431     if (llvm::Triple::riscv32 == machine) {
432       raw_value = reg_ctx->ReadRegisterAsUnsigned(reg_info_a0, 0) & UINT32_MAX;
433       raw_value |=
434           (reg_ctx->ReadRegisterAsUnsigned(reg_info_a1, 0) & UINT32_MAX) << 32U;
435     } else {
436       raw_value = reg_ctx->ReadRegisterAsUnsigned(reg_info_a0, 0);
437     }
438     break;
439   case 16: {
440     // Read a0 and a1 to get the arg on riscv64, not supported on riscv32
441     if (llvm::Triple::riscv32 == machine)
442       return return_valobj_sp;
443 
444     // Create the ValueObjectSP here and return
445     std::unique_ptr<DataBufferHeap> heap_data_up(
446         new DataBufferHeap(byte_size, 0));
447     const ByteOrder byte_order = thread.GetProcess()->GetByteOrder();
448     RegisterValue reg_value_a0, reg_value_a1;
449     if (reg_ctx->ReadRegister(reg_info_a0, reg_value_a0) &&
450         reg_ctx->ReadRegister(reg_info_a1, reg_value_a1)) {
451       Status error;
452       if (reg_value_a0.GetAsMemoryData(*reg_info_a0,
453                                        heap_data_up->GetBytes() + 0, 8,
454                                        byte_order, error) &&
455           reg_value_a1.GetAsMemoryData(*reg_info_a1,
456                                        heap_data_up->GetBytes() + 8, 8,
457                                        byte_order, error)) {
458         value.SetBytes(heap_data_up.release(), byte_size);
459         return ValueObjectConstResult::Create(
460             thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));
461       }
462     }
463     break;
464   }
465   default:
466     return return_valobj_sp;
467   }
468 
469   if (type_flags & eTypeIsInteger) {
470     const bool is_signed = (type_flags & eTypeIsSigned) != 0;
471     if (!SetSizedInteger(value.GetScalar(), raw_value, byte_size, is_signed))
472       return return_valobj_sp;
473   } else if (type_flags & eTypeIsFloat) {
474     if (!SetSizedFloat(value.GetScalar(), raw_value, byte_size))
475       return return_valobj_sp;
476   } else
477     return return_valobj_sp;
478 
479   value.SetValueType(Value::ValueType::Scalar);
480   return_valobj_sp = ValueObjectConstResult::Create(
481       thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));
482   return return_valobj_sp;
483 }
484 
485 static ValueObjectSP
486 GetValObjFromFPRegs(Thread &thread, const RegisterContextSP &reg_ctx,
487                     llvm::Triple::ArchType machine, uint32_t arch_fp_flags,
488                     uint32_t type_flags, uint32_t byte_size) {
489   auto reg_info_fa0 = reg_ctx->GetRegisterInfoByName("fa0");
490   bool use_fp_regs = false;
491   ValueObjectSP return_valobj_sp;
492 
493   switch (arch_fp_flags) {
494   // fp return value in integer registers a0 and possibly a1
495   case ArchSpec::eRISCV_float_abi_soft:
496     return_valobj_sp =
497         GetValObjFromIntRegs(thread, reg_ctx, machine, type_flags, byte_size);
498     return return_valobj_sp;
499   // fp return value in fp register fa0 (only float)
500   case ArchSpec::eRISCV_float_abi_single:
501     if (byte_size <= 4)
502       use_fp_regs = true;
503     break;
504   // fp return value in fp registers fa0 (float, double)
505   case ArchSpec::eRISCV_float_abi_double:
506     [[fallthrough]];
507   // fp return value in fp registers fa0 (float, double, quad)
508   // not implemented; act like they're doubles
509   case ArchSpec::eRISCV_float_abi_quad:
510     if (byte_size <= 8)
511       use_fp_regs = true;
512     break;
513   }
514 
515   if (use_fp_regs) {
516     uint64_t raw_value;
517     Value value;
518     raw_value = reg_ctx->ReadRegisterAsUnsigned(reg_info_fa0, 0);
519     if (!SetSizedFloat(value.GetScalar(), raw_value, byte_size))
520       return return_valobj_sp;
521     value.SetValueType(Value::ValueType::Scalar);
522     return ValueObjectConstResult::Create(thread.GetStackFrameAtIndex(0).get(),
523                                           value, ConstString(""));
524   }
525   // we should never reach this, but if we do, use the integer registers
526   return GetValObjFromIntRegs(thread, reg_ctx, machine, type_flags, byte_size);
527 }
528 
529 ValueObjectSP
530 ABISysV_riscv::GetReturnValueObjectSimple(Thread &thread,
531                                           CompilerType &compiler_type) const {
532   ValueObjectSP return_valobj_sp;
533 
534   if (!compiler_type)
535     return return_valobj_sp;
536 
537   auto reg_ctx = thread.GetRegisterContext();
538   if (!reg_ctx)
539     return return_valobj_sp;
540 
541   Value value;
542   value.SetCompilerType(compiler_type);
543 
544   const uint32_t type_flags = compiler_type.GetTypeInfo();
545   const size_t byte_size = compiler_type.GetByteSize(&thread).value_or(0);
546   const ArchSpec arch = thread.GetProcess()->GetTarget().GetArchitecture();
547   const llvm::Triple::ArchType machine = arch.GetMachine();
548 
549   // Integer return type.
550   if (type_flags & eTypeIsInteger) {
551     return_valobj_sp =
552         GetValObjFromIntRegs(thread, reg_ctx, machine, type_flags, byte_size);
553     return return_valobj_sp;
554   }
555   // Pointer return type.
556   else if (type_flags & eTypeIsPointer) {
557     auto reg_info_a0 = reg_ctx->GetRegisterInfo(eRegisterKindGeneric,
558                                                 LLDB_REGNUM_GENERIC_ARG1);
559     value.GetScalar() = reg_ctx->ReadRegisterAsUnsigned(reg_info_a0, 0);
560     value.SetValueType(Value::ValueType::Scalar);
561     return ValueObjectConstResult::Create(thread.GetStackFrameAtIndex(0).get(),
562                                           value, ConstString(""));
563   }
564   // Floating point return type.
565   else if (type_flags & eTypeIsFloat) {
566     uint32_t float_count = 0;
567     bool is_complex = false;
568 
569     if (compiler_type.IsFloatingPointType(float_count, is_complex) &&
570         float_count == 1 && !is_complex) {
571       const uint32_t arch_fp_flags =
572           arch.GetFlags() & ArchSpec::eRISCV_float_abi_mask;
573       return_valobj_sp = GetValObjFromFPRegs(
574           thread, reg_ctx, machine, arch_fp_flags, type_flags, byte_size);
575       return return_valobj_sp;
576     }
577   }
578   // Unsupported return type.
579   return return_valobj_sp;
580 }
581 
582 ValueObjectSP
583 ABISysV_riscv::GetReturnValueObjectImpl(lldb_private::Thread &thread,
584                                         llvm::Type &type) const {
585   Value value;
586   ValueObjectSP return_valobj_sp;
587 
588   auto reg_ctx = thread.GetRegisterContext();
589   if (!reg_ctx)
590     return return_valobj_sp;
591 
592   uint32_t type_flags = 0;
593   if (type.isIntegerTy())
594     type_flags = eTypeIsInteger;
595   else if (type.isVoidTy())
596     type_flags = eTypeIsPointer;
597   else if (type.isFloatTy())
598     type_flags = eTypeIsFloat;
599 
600   const uint32_t byte_size = type.getPrimitiveSizeInBits() / CHAR_BIT;
601   const ArchSpec arch = thread.GetProcess()->GetTarget().GetArchitecture();
602   const llvm::Triple::ArchType machine = arch.GetMachine();
603 
604   // Integer return type.
605   if (type_flags & eTypeIsInteger) {
606     return_valobj_sp =
607         GetValObjFromIntRegs(thread, reg_ctx, machine, type_flags, byte_size);
608     return return_valobj_sp;
609   }
610   // Pointer return type.
611   else if (type_flags & eTypeIsPointer) {
612     auto reg_info_a0 = reg_ctx->GetRegisterInfo(eRegisterKindGeneric,
613                                                 LLDB_REGNUM_GENERIC_ARG1);
614     value.GetScalar() = reg_ctx->ReadRegisterAsUnsigned(reg_info_a0, 0);
615     value.SetValueType(Value::ValueType::Scalar);
616     return ValueObjectConstResult::Create(thread.GetStackFrameAtIndex(0).get(),
617                                           value, ConstString(""));
618   }
619   // Floating point return type.
620   else if (type_flags & eTypeIsFloat) {
621     const uint32_t arch_fp_flags =
622         arch.GetFlags() & ArchSpec::eRISCV_float_abi_mask;
623     return_valobj_sp = GetValObjFromFPRegs(
624         thread, reg_ctx, machine, arch_fp_flags, type_flags, byte_size);
625     return return_valobj_sp;
626   }
627   // Unsupported return type.
628   return return_valobj_sp;
629 }
630 
631 ValueObjectSP ABISysV_riscv::GetReturnValueObjectImpl(
632     Thread &thread, CompilerType &return_compiler_type) const {
633   ValueObjectSP return_valobj_sp;
634 
635   if (!return_compiler_type)
636     return return_valobj_sp;
637 
638   ExecutionContext exe_ctx(thread.shared_from_this());
639   return GetReturnValueObjectSimple(thread, return_compiler_type);
640 }
641 
642 bool ABISysV_riscv::CreateFunctionEntryUnwindPlan(UnwindPlan &unwind_plan) {
643   unwind_plan.Clear();
644   unwind_plan.SetRegisterKind(eRegisterKindDWARF);
645 
646   uint32_t pc_reg_num = LLDB_REGNUM_GENERIC_PC;
647   uint32_t sp_reg_num = LLDB_REGNUM_GENERIC_SP;
648   uint32_t ra_reg_num = LLDB_REGNUM_GENERIC_RA;
649 
650   UnwindPlan::RowSP row(new UnwindPlan::Row);
651 
652   // Define CFA as the stack pointer
653   row->GetCFAValue().SetIsRegisterPlusOffset(sp_reg_num, 0);
654 
655   // Previous frame's pc is in ra
656 
657   row->SetRegisterLocationToRegister(pc_reg_num, ra_reg_num, true);
658   unwind_plan.AppendRow(row);
659   unwind_plan.SetSourceName("riscv function-entry unwind plan");
660   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
661 
662   return true;
663 }
664 
665 bool ABISysV_riscv::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
666   unwind_plan.Clear();
667   unwind_plan.SetRegisterKind(eRegisterKindGeneric);
668 
669   uint32_t pc_reg_num = LLDB_REGNUM_GENERIC_PC;
670   uint32_t fp_reg_num = LLDB_REGNUM_GENERIC_FP;
671 
672   UnwindPlan::RowSP row(new UnwindPlan::Row);
673 
674   // Define the CFA as the current frame pointer value.
675   row->GetCFAValue().SetIsRegisterPlusOffset(fp_reg_num, 0);
676   row->SetOffset(0);
677 
678   int reg_size = 4;
679   if (m_is_rv64)
680     reg_size = 8;
681 
682   // Assume the ra reg (return pc) and caller's frame pointer
683   // have been spilled to stack already.
684   row->SetRegisterLocationToAtCFAPlusOffset(fp_reg_num, reg_size * -2, true);
685   row->SetRegisterLocationToAtCFAPlusOffset(pc_reg_num, reg_size * -1, true);
686 
687   unwind_plan.AppendRow(row);
688   unwind_plan.SetSourceName("riscv default unwind plan");
689   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
690   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
691   return true;
692 }
693 
694 bool ABISysV_riscv::RegisterIsVolatile(const RegisterInfo *reg_info) {
695   return !RegisterIsCalleeSaved(reg_info);
696 }
697 
698 bool ABISysV_riscv::RegisterIsCalleeSaved(const RegisterInfo *reg_info) {
699   if (!reg_info)
700     return false;
701 
702   const char *name = reg_info->name;
703   ArchSpec arch = GetProcessSP()->GetTarget().GetArchitecture();
704   uint32_t arch_flags = arch.GetFlags();
705   // floating point registers are only callee saved when using
706   // F, D or Q hardware floating point ABIs
707   bool is_hw_fp = (arch_flags & ArchSpec::eRISCV_float_abi_mask) != 0;
708 
709   bool is_callee_saved =
710       llvm::StringSwitch<bool>(name)
711           // integer ABI names
712           .Cases("ra", "sp", "fp", true)
713           .Cases("s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7", "s8", "s9",
714                  true)
715           .Cases("s10", "s11", true)
716           // integer hardware names
717           .Cases("x1", "x2", "x8", "x9", "x18", "x19", "x20", "x21", "x22",
718                  true)
719           .Cases("x23", "x24", "x25", "x26", "x27", true)
720           // floating point ABI names
721           .Cases("fs0", "fs1", "fs2", "fs3", "fs4", "fs5", "fs6", "fs7",
722                  is_hw_fp)
723           .Cases("fs8", "fs9", "fs10", "fs11", is_hw_fp)
724           // floating point hardware names
725           .Cases("f8", "f9", "f18", "f19", "f20", "f21", "f22", "f23", is_hw_fp)
726           .Cases("f24", "f25", "f26", "f27", is_hw_fp)
727           .Default(false);
728 
729   return is_callee_saved;
730 }
731 
732 void ABISysV_riscv::Initialize() {
733   PluginManager::RegisterPlugin(
734       GetPluginNameStatic(), "System V ABI for RISCV targets", CreateInstance);
735 }
736 
737 void ABISysV_riscv::Terminate() {
738   PluginManager::UnregisterPlugin(CreateInstance);
739 }
740 
741 static uint32_t GetGenericNum(llvm::StringRef name) {
742   return llvm::StringSwitch<uint32_t>(name)
743       .Case("pc", LLDB_REGNUM_GENERIC_PC)
744       .Cases("ra", "x1", LLDB_REGNUM_GENERIC_RA)
745       .Cases("sp", "x2", LLDB_REGNUM_GENERIC_SP)
746       .Cases("fp", "s0", LLDB_REGNUM_GENERIC_FP)
747       .Case("a0", LLDB_REGNUM_GENERIC_ARG1)
748       .Case("a1", LLDB_REGNUM_GENERIC_ARG2)
749       .Case("a2", LLDB_REGNUM_GENERIC_ARG3)
750       .Case("a3", LLDB_REGNUM_GENERIC_ARG4)
751       .Case("a4", LLDB_REGNUM_GENERIC_ARG5)
752       .Case("a5", LLDB_REGNUM_GENERIC_ARG6)
753       .Case("a6", LLDB_REGNUM_GENERIC_ARG7)
754       .Case("a7", LLDB_REGNUM_GENERIC_ARG8)
755       .Default(LLDB_INVALID_REGNUM);
756 }
757 
758 void ABISysV_riscv::AugmentRegisterInfo(
759     std::vector<lldb_private::DynamicRegisterInfo::Register> &regs) {
760   lldb_private::RegInfoBasedABI::AugmentRegisterInfo(regs);
761 
762   for (auto it : llvm::enumerate(regs)) {
763     // Set alt name for certain registers for convenience
764     if (it.value().name == "zero")
765       it.value().alt_name.SetCString("x0");
766     else if (it.value().name == "ra")
767       it.value().alt_name.SetCString("x1");
768     else if (it.value().name == "sp")
769       it.value().alt_name.SetCString("x2");
770     else if (it.value().name == "gp")
771       it.value().alt_name.SetCString("x3");
772     else if (it.value().name == "fp")
773       it.value().alt_name.SetCString("s0");
774     else if (it.value().name == "s0")
775       it.value().alt_name.SetCString("x8");
776 
777     // Set generic regnum so lldb knows what the PC, etc is
778     it.value().regnum_generic = GetGenericNum(it.value().name.GetStringRef());
779   }
780 }
781