lldb/source/Plugins/ABI/SystemZ/ABISysV_s390x.cpp

   1 //===-- ABISysV_s390x.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_s390x.h"
  10
  11 #include "llvm/ADT/STLExtras.h"
  12 #include "llvm/TargetParser/Triple.h"
  13
  14 #include "lldb/Core/Module.h"
  15 #include "lldb/Core/PluginManager.h"
  16 #include "lldb/Core/Value.h"
  17 #include "lldb/Core/ValueObjectConstResult.h"
  18 #include "lldb/Core/ValueObjectMemory.h"
  19 #include "lldb/Core/ValueObjectRegister.h"
  20 #include "lldb/Symbol/UnwindPlan.h"
  21 #include "lldb/Target/Process.h"
  22 #include "lldb/Target/RegisterContext.h"
  23 #include "lldb/Target/StackFrame.h"
  24 #include "lldb/Target/Target.h"
  25 #include "lldb/Target/Thread.h"
  26 #include "lldb/Utility/ConstString.h"
  27 #include "lldb/Utility/DataExtractor.h"
  28 #include "lldb/Utility/LLDBLog.h"
  29 #include "lldb/Utility/Log.h"
  30 #include "lldb/Utility/RegisterValue.h"
  31 #include "lldb/Utility/Status.h"
  32 #include <optional>
  33
  34 using namespace lldb;
  35 using namespace lldb_private;
  36
  37 LLDB_PLUGIN_DEFINE_ADV(ABISysV_s390x, ABISystemZ)
  38
  39 enum dwarf_regnums {
  40   // General Purpose Registers
  41   dwarf_r0_s390x = 0,
  42   dwarf_r1_s390x,
  43   dwarf_r2_s390x,
  44   dwarf_r3_s390x,
  45   dwarf_r4_s390x,
  46   dwarf_r5_s390x,
  47   dwarf_r6_s390x,
  48   dwarf_r7_s390x,
  49   dwarf_r8_s390x,
  50   dwarf_r9_s390x,
  51   dwarf_r10_s390x,
  52   dwarf_r11_s390x,
  53   dwarf_r12_s390x,
  54   dwarf_r13_s390x,
  55   dwarf_r14_s390x,
  56   dwarf_r15_s390x,
  57   // Floating Point Registers / Vector Registers 0-15
  58   dwarf_f0_s390x = 16,
  59   dwarf_f2_s390x,
  60   dwarf_f4_s390x,
  61   dwarf_f6_s390x,
  62   dwarf_f1_s390x,
  63   dwarf_f3_s390x,
  64   dwarf_f5_s390x,
  65   dwarf_f7_s390x,
  66   dwarf_f8_s390x,
  67   dwarf_f10_s390x,
  68   dwarf_f12_s390x,
  69   dwarf_f14_s390x,
  70   dwarf_f9_s390x,
  71   dwarf_f11_s390x,
  72   dwarf_f13_s390x,
  73   dwarf_f15_s390x,
  74   // Access Registers
  75   dwarf_acr0_s390x = 48,
  76   dwarf_acr1_s390x,
  77   dwarf_acr2_s390x,
  78   dwarf_acr3_s390x,
  79   dwarf_acr4_s390x,
  80   dwarf_acr5_s390x,
  81   dwarf_acr6_s390x,
  82   dwarf_acr7_s390x,
  83   dwarf_acr8_s390x,
  84   dwarf_acr9_s390x,
  85   dwarf_acr10_s390x,
  86   dwarf_acr11_s390x,
  87   dwarf_acr12_s390x,
  88   dwarf_acr13_s390x,
  89   dwarf_acr14_s390x,
  90   dwarf_acr15_s390x,
  91   // Program Status Word
  92   dwarf_pswm_s390x = 64,
  93   dwarf_pswa_s390x,
  94   // Vector Registers 16-31
  95   dwarf_v16_s390x = 68,
  96   dwarf_v18_s390x,
  97   dwarf_v20_s390x,
  98   dwarf_v22_s390x,
  99   dwarf_v17_s390x,
 100   dwarf_v19_s390x,
 101   dwarf_v21_s390x,
 102   dwarf_v23_s390x,
 103   dwarf_v24_s390x,
 104   dwarf_v26_s390x,
 105   dwarf_v28_s390x,
 106   dwarf_v30_s390x,
 107   dwarf_v25_s390x,
 108   dwarf_v27_s390x,
 109   dwarf_v29_s390x,
 110   dwarf_v31_s390x,
 111 };
 112
 113 // RegisterKind: EHFrame, DWARF, Generic, Process Plugin, LLDB
 114
 115 #define DEFINE_REG(name, size, alt, generic)                                   \
 116   {                                                                            \
 117     #name, alt, size, 0, eEncodingUint, eFormatHex,                            \
 118         {dwarf_##name##_s390x, dwarf_##name##_s390x, generic,                  \
 119          LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM },                           \
 120          nullptr, nullptr, nullptr,                                            \
 121   }
 122
 123 static const RegisterInfo g_register_infos[] = {
 124     DEFINE_REG(r0, 8, nullptr, LLDB_INVALID_REGNUM),
 125     DEFINE_REG(r1, 8, nullptr, LLDB_INVALID_REGNUM),
 126     DEFINE_REG(r2, 8, nullptr, LLDB_REGNUM_GENERIC_ARG1),
 127     DEFINE_REG(r3, 8, nullptr, LLDB_REGNUM_GENERIC_ARG2),
 128     DEFINE_REG(r4, 8, nullptr, LLDB_REGNUM_GENERIC_ARG3),
 129     DEFINE_REG(r5, 8, nullptr, LLDB_REGNUM_GENERIC_ARG4),
 130     DEFINE_REG(r6, 8, nullptr, LLDB_REGNUM_GENERIC_ARG5),
 131     DEFINE_REG(r7, 8, nullptr, LLDB_INVALID_REGNUM),
 132     DEFINE_REG(r8, 8, nullptr, LLDB_INVALID_REGNUM),
 133     DEFINE_REG(r9, 8, nullptr, LLDB_INVALID_REGNUM),
 134     DEFINE_REG(r10, 8, nullptr, LLDB_INVALID_REGNUM),
 135     DEFINE_REG(r11, 8, nullptr, LLDB_REGNUM_GENERIC_FP),
 136     DEFINE_REG(r12, 8, nullptr, LLDB_INVALID_REGNUM),
 137     DEFINE_REG(r13, 8, nullptr, LLDB_INVALID_REGNUM),
 138     DEFINE_REG(r14, 8, nullptr, LLDB_INVALID_REGNUM),
 139     DEFINE_REG(r15, 8, "sp", LLDB_REGNUM_GENERIC_SP),
 140     DEFINE_REG(acr0, 4, nullptr, LLDB_INVALID_REGNUM),
 141     DEFINE_REG(acr1, 4, nullptr, LLDB_INVALID_REGNUM),
 142     DEFINE_REG(acr2, 4, nullptr, LLDB_INVALID_REGNUM),
 143     DEFINE_REG(acr3, 4, nullptr, LLDB_INVALID_REGNUM),
 144     DEFINE_REG(acr4, 4, nullptr, LLDB_INVALID_REGNUM),
 145     DEFINE_REG(acr5, 4, nullptr, LLDB_INVALID_REGNUM),
 146     DEFINE_REG(acr6, 4, nullptr, LLDB_INVALID_REGNUM),
 147     DEFINE_REG(acr7, 4, nullptr, LLDB_INVALID_REGNUM),
 148     DEFINE_REG(acr8, 4, nullptr, LLDB_INVALID_REGNUM),
 149     DEFINE_REG(acr9, 4, nullptr, LLDB_INVALID_REGNUM),
 150     DEFINE_REG(acr10, 4, nullptr, LLDB_INVALID_REGNUM),
 151     DEFINE_REG(acr11, 4, nullptr, LLDB_INVALID_REGNUM),
 152     DEFINE_REG(acr12, 4, nullptr, LLDB_INVALID_REGNUM),
 153     DEFINE_REG(acr13, 4, nullptr, LLDB_INVALID_REGNUM),
 154     DEFINE_REG(acr14, 4, nullptr, LLDB_INVALID_REGNUM),
 155     DEFINE_REG(acr15, 4, nullptr, LLDB_INVALID_REGNUM),
 156     DEFINE_REG(pswm, 8, nullptr, LLDB_REGNUM_GENERIC_FLAGS),
 157     DEFINE_REG(pswa, 8, nullptr, LLDB_REGNUM_GENERIC_PC),
 158     DEFINE_REG(f0, 8, nullptr, LLDB_INVALID_REGNUM),
 159     DEFINE_REG(f1, 8, nullptr, LLDB_INVALID_REGNUM),
 160     DEFINE_REG(f2, 8, nullptr, LLDB_INVALID_REGNUM),
 161     DEFINE_REG(f3, 8, nullptr, LLDB_INVALID_REGNUM),
 162     DEFINE_REG(f4, 8, nullptr, LLDB_INVALID_REGNUM),
 163     DEFINE_REG(f5, 8, nullptr, LLDB_INVALID_REGNUM),
 164     DEFINE_REG(f6, 8, nullptr, LLDB_INVALID_REGNUM),
 165     DEFINE_REG(f7, 8, nullptr, LLDB_INVALID_REGNUM),
 166     DEFINE_REG(f8, 8, nullptr, LLDB_INVALID_REGNUM),
 167     DEFINE_REG(f9, 8, nullptr, LLDB_INVALID_REGNUM),
 168     DEFINE_REG(f10, 8, nullptr, LLDB_INVALID_REGNUM),
 169     DEFINE_REG(f11, 8, nullptr, LLDB_INVALID_REGNUM),
 170     DEFINE_REG(f12, 8, nullptr, LLDB_INVALID_REGNUM),
 171     DEFINE_REG(f13, 8, nullptr, LLDB_INVALID_REGNUM),
 172     DEFINE_REG(f14, 8, nullptr, LLDB_INVALID_REGNUM),
 173     DEFINE_REG(f15, 8, nullptr, LLDB_INVALID_REGNUM),
 174 };
 175
 176 static const uint32_t k_num_register_infos = std::size(g_register_infos);
 177
 178 const lldb_private::RegisterInfo *
 179 ABISysV_s390x::GetRegisterInfoArray(uint32_t &count) {
 180   count = k_num_register_infos;
 181   return g_register_infos;
 182 }
 183
 184 size_t ABISysV_s390x::GetRedZoneSize() const { return 0; }
 185
 186 // Static Functions
 187
 188 ABISP
 189 ABISysV_s390x::CreateInstance(lldb::ProcessSP process_sp, const ArchSpec &arch) {
 190   if (arch.GetTriple().getArch() == llvm::Triple::systemz) {
 191     return ABISP(new ABISysV_s390x(std::move(process_sp), MakeMCRegisterInfo(arch)));
 192   }
 193   return ABISP();
 194 }
 195
 196 bool ABISysV_s390x::PrepareTrivialCall(Thread &thread, addr_t sp,
 197                                        addr_t func_addr, addr_t return_addr,
 198                                        llvm::ArrayRef<addr_t> args) const {
 199   Log *log = GetLog(LLDBLog::Expressions);
 200
 201   if (log) {
 202     StreamString s;
 203     s.Printf("ABISysV_s390x::PrepareTrivialCall (tid = 0x%" PRIx64
 204              ", sp = 0x%" PRIx64 ", func_addr = 0x%" PRIx64
 205              ", return_addr = 0x%" PRIx64,
 206              thread.GetID(), (uint64_t)sp, (uint64_t)func_addr,
 207              (uint64_t)return_addr);
 208
 209     for (size_t i = 0; i < args.size(); ++i)
 210       s.Printf(", arg%" PRIu64 " = 0x%" PRIx64, static_cast<uint64_t>(i + 1),
 211                args[i]);
 212     s.PutCString(")");
 213     log->PutString(s.GetString());
 214   }
 215
 216   RegisterContext *reg_ctx = thread.GetRegisterContext().get();
 217   if (!reg_ctx)
 218     return false;
 219
 220   const RegisterInfo *pc_reg_info =
 221       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
 222   const RegisterInfo *sp_reg_info =
 223       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
 224   const RegisterInfo *ra_reg_info = reg_ctx->GetRegisterInfoByName("r14", 0);
 225   ProcessSP process_sp(thread.GetProcess());
 226
 227   // Allocate a new stack frame and space for stack arguments if necessary
 228
 229   addr_t arg_pos = 0;
 230   if (args.size() > 5) {
 231     sp -= 8 * (args.size() - 5);
 232     arg_pos = sp;
 233   }
 234
 235   sp -= 160;
 236
 237   // Process arguments
 238
 239   for (size_t i = 0; i < args.size(); ++i) {
 240     if (i < 5) {
 241       const RegisterInfo *reg_info = reg_ctx->GetRegisterInfo(
 242           eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + i);
 243       LLDB_LOGF(log, "About to write arg%" PRIu64 " (0x%" PRIx64 ") into %s",
 244                 static_cast<uint64_t>(i + 1), args[i], reg_info->name);
 245       if (!reg_ctx->WriteRegisterFromUnsigned(reg_info, args[i]))
 246         return false;
 247     } else {
 248       Status error;
 249       LLDB_LOGF(log, "About to write arg%" PRIu64 " (0x%" PRIx64 ") onto stack",
 250                 static_cast<uint64_t>(i + 1), args[i]);
 251       if (!process_sp->WritePointerToMemory(arg_pos, args[i], error))
 252         return false;
 253       arg_pos += 8;
 254     }
 255   }
 256
 257   // %r14 is set to the return address
 258
 259   LLDB_LOGF(log, "Writing RA: 0x%" PRIx64, (uint64_t)return_addr);
 260
 261   if (!reg_ctx->WriteRegisterFromUnsigned(ra_reg_info, return_addr))
 262     return false;
 263
 264   // %r15 is set to the actual stack value.
 265
 266   LLDB_LOGF(log, "Writing SP: 0x%" PRIx64, (uint64_t)sp);
 267
 268   if (!reg_ctx->WriteRegisterFromUnsigned(sp_reg_info, sp))
 269     return false;
 270
 271   // %pc is set to the address of the called function.
 272
 273   LLDB_LOGF(log, "Writing PC: 0x%" PRIx64, (uint64_t)func_addr);
 274
 275   if (!reg_ctx->WriteRegisterFromUnsigned(pc_reg_info, func_addr))
 276     return false;
 277
 278   return true;
 279 }
 280
 281 static bool ReadIntegerArgument(Scalar &scalar, unsigned int bit_width,
 282                                 bool is_signed, Thread &thread,
 283                                 uint32_t *argument_register_ids,
 284                                 unsigned int &current_argument_register,
 285                                 addr_t &current_stack_argument) {
 286   if (bit_width > 64)
 287     return false; // Scalar can't hold large integer arguments
 288
 289   if (current_argument_register < 5) {
 290     scalar = thread.GetRegisterContext()->ReadRegisterAsUnsigned(
 291         argument_register_ids[current_argument_register], 0);
 292     current_argument_register++;
 293     if (is_signed)
 294       scalar.SignExtend(bit_width);
 295   } else {
 296     uint32_t byte_size = (bit_width + (8 - 1)) / 8;
 297     Status error;
 298     if (thread.GetProcess()->ReadScalarIntegerFromMemory(
 299             current_stack_argument + 8 - byte_size, byte_size, is_signed,
 300             scalar, error)) {
 301       current_stack_argument += 8;
 302       return true;
 303     }
 304     return false;
 305   }
 306   return true;
 307 }
 308
 309 bool ABISysV_s390x::GetArgumentValues(Thread &thread, ValueList &values) const {
 310   unsigned int num_values = values.GetSize();
 311   unsigned int value_index;
 312
 313   // Extract the register context so we can read arguments from registers
 314
 315   RegisterContext *reg_ctx = thread.GetRegisterContext().get();
 316
 317   if (!reg_ctx)
 318     return false;
 319
 320   // Get the pointer to the first stack argument so we have a place to start
 321   // when reading data
 322
 323   addr_t sp = reg_ctx->GetSP(0);
 324
 325   if (!sp)
 326     return false;
 327
 328   addr_t current_stack_argument = sp + 160;
 329
 330   uint32_t argument_register_ids[5];
 331
 332   argument_register_ids[0] =
 333       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1)
 334           ->kinds[eRegisterKindLLDB];
 335   argument_register_ids[1] =
 336       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG2)
 337           ->kinds[eRegisterKindLLDB];
 338   argument_register_ids[2] =
 339       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG3)
 340           ->kinds[eRegisterKindLLDB];
 341   argument_register_ids[3] =
 342       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG4)
 343           ->kinds[eRegisterKindLLDB];
 344   argument_register_ids[4] =
 345       reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG5)
 346           ->kinds[eRegisterKindLLDB];
 347
 348   unsigned int current_argument_register = 0;
 349
 350   for (value_index = 0; value_index < num_values; ++value_index) {
 351     Value *value = values.GetValueAtIndex(value_index);
 352
 353     if (!value)
 354       return false;
 355
 356     // We currently only support extracting values with Clang QualTypes. Do we
 357     // care about others?
 358     CompilerType compiler_type = value->GetCompilerType();
 359     std::optional<uint64_t> bit_size = compiler_type.GetBitSize(&thread);
 360     if (!bit_size)
 361       return false;
 362     bool is_signed;
 363
 364     if (compiler_type.IsIntegerOrEnumerationType(is_signed)) {
 365       ReadIntegerArgument(value->GetScalar(), *bit_size, is_signed, thread,
 366                           argument_register_ids, current_argument_register,
 367                           current_stack_argument);
 368     } else if (compiler_type.IsPointerType()) {
 369       ReadIntegerArgument(value->GetScalar(), *bit_size, false, thread,
 370                           argument_register_ids, current_argument_register,
 371                           current_stack_argument);
 372     }
 373   }
 374
 375   return true;
 376 }
 377
 378 Status ABISysV_s390x::SetReturnValueObject(lldb::StackFrameSP &frame_sp,
 379                                            lldb::ValueObjectSP &new_value_sp) {
 380   Status error;
 381   if (!new_value_sp) {
 382     error.SetErrorString("Empty value object for return value.");
 383     return error;
 384   }
 385
 386   CompilerType compiler_type = new_value_sp->GetCompilerType();
 387   if (!compiler_type) {
 388     error.SetErrorString("Null clang type for return value.");
 389     return error;
 390   }
 391
 392   Thread *thread = frame_sp->GetThread().get();
 393
 394   bool is_signed;
 395   uint32_t count;
 396   bool is_complex;
 397
 398   RegisterContext *reg_ctx = thread->GetRegisterContext().get();
 399
 400   bool set_it_simple = false;
 401   if (compiler_type.IsIntegerOrEnumerationType(is_signed) ||
 402       compiler_type.IsPointerType()) {
 403     const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoByName("r2", 0);
 404
 405     DataExtractor data;
 406     Status data_error;
 407     size_t num_bytes = new_value_sp->GetData(data, data_error);
 408     if (data_error.Fail()) {
 409       error.SetErrorStringWithFormat(
 410           "Couldn't convert return value to raw data: %s",
 411           data_error.AsCString());
 412       return error;
 413     }
 414     lldb::offset_t offset = 0;
 415     if (num_bytes <= 8) {
 416       uint64_t raw_value = data.GetMaxU64(&offset, num_bytes);
 417
 418       if (reg_ctx->WriteRegisterFromUnsigned(reg_info, raw_value))
 419         set_it_simple = true;
 420     } else {
 421       error.SetErrorString("We don't support returning longer than 64 bit "
 422                            "integer values at present.");
 423     }
 424   } else if (compiler_type.IsFloatingPointType(count, is_complex)) {
 425     if (is_complex)
 426       error.SetErrorString(
 427           "We don't support returning complex values at present");
 428     else {
 429       std::optional<uint64_t> bit_width =
 430           compiler_type.GetBitSize(frame_sp.get());
 431       if (!bit_width) {
 432         error.SetErrorString("can't get type size");
 433         return error;
 434       }
 435       if (*bit_width <= 64) {
 436         const RegisterInfo *f0_info = reg_ctx->GetRegisterInfoByName("f0", 0);
 437         RegisterValue f0_value;
 438         DataExtractor data;
 439         Status data_error;
 440         size_t num_bytes = new_value_sp->GetData(data, data_error);
 441         if (data_error.Fail()) {
 442           error.SetErrorStringWithFormat(
 443               "Couldn't convert return value to raw data: %s",
 444               data_error.AsCString());
 445           return error;
 446         }
 447
 448         unsigned char buffer[8];
 449         ByteOrder byte_order = data.GetByteOrder();
 450
 451         data.CopyByteOrderedData(0, num_bytes, buffer, 8, byte_order);
 452         f0_value.SetBytes(buffer, 8, byte_order);
 453         reg_ctx->WriteRegister(f0_info, f0_value);
 454         set_it_simple = true;
 455       } else {
 456         // FIXME - don't know how to do long doubles yet.
 457         error.SetErrorString(
 458             "We don't support returning float values > 64 bits at present");
 459       }
 460     }
 461   }
 462
 463   if (!set_it_simple) {
 464     // Okay we've got a structure or something that doesn't fit in a simple
 465     // register. We should figure out where it really goes, but we don't
 466     // support this yet.
 467     error.SetErrorString("We only support setting simple integer and float "
 468                          "return types at present.");
 469   }
 470
 471   return error;
 472 }
 473
 474 ValueObjectSP ABISysV_s390x::GetReturnValueObjectSimple(
 475     Thread &thread, CompilerType &return_compiler_type) const {
 476   ValueObjectSP return_valobj_sp;
 477   Value value;
 478
 479   if (!return_compiler_type)
 480     return return_valobj_sp;
 481
 482   // value.SetContext (Value::eContextTypeClangType, return_value_type);
 483   value.SetCompilerType(return_compiler_type);
 484
 485   RegisterContext *reg_ctx = thread.GetRegisterContext().get();
 486   if (!reg_ctx)
 487     return return_valobj_sp;
 488
 489   const uint32_t type_flags = return_compiler_type.GetTypeInfo();
 490   if (type_flags & eTypeIsScalar) {
 491     value.SetValueType(Value::ValueType::Scalar);
 492
 493     bool success = false;
 494     if (type_flags & eTypeIsInteger) {
 495       // Extract the register context so we can read arguments from registers.
 496       std::optional<uint64_t> byte_size =
 497           return_compiler_type.GetByteSize(&thread);
 498       if (!byte_size)
 499         return return_valobj_sp;
 500       uint64_t raw_value = thread.GetRegisterContext()->ReadRegisterAsUnsigned(
 501           reg_ctx->GetRegisterInfoByName("r2", 0), 0);
 502       const bool is_signed = (type_flags & eTypeIsSigned) != 0;
 503       switch (*byte_size) {
 504       default:
 505         break;
 506
 507       case sizeof(uint64_t):
 508         if (is_signed)
 509           value.GetScalar() = (int64_t)(raw_value);
 510         else
 511           value.GetScalar() = (uint64_t)(raw_value);
 512         success = true;
 513         break;
 514
 515       case sizeof(uint32_t):
 516         if (is_signed)
 517           value.GetScalar() = (int32_t)(raw_value & UINT32_MAX);
 518         else
 519           value.GetScalar() = (uint32_t)(raw_value & UINT32_MAX);
 520         success = true;
 521         break;
 522
 523       case sizeof(uint16_t):
 524         if (is_signed)
 525           value.GetScalar() = (int16_t)(raw_value & UINT16_MAX);
 526         else
 527           value.GetScalar() = (uint16_t)(raw_value & UINT16_MAX);
 528         success = true;
 529         break;
 530
 531       case sizeof(uint8_t):
 532         if (is_signed)
 533           value.GetScalar() = (int8_t)(raw_value & UINT8_MAX);
 534         else
 535           value.GetScalar() = (uint8_t)(raw_value & UINT8_MAX);
 536         success = true;
 537         break;
 538       }
 539     } else if (type_flags & eTypeIsFloat) {
 540       if (type_flags & eTypeIsComplex) {
 541         // Don't handle complex yet.
 542       } else {
 543         std::optional<uint64_t> byte_size =
 544             return_compiler_type.GetByteSize(&thread);
 545         if (byte_size && *byte_size <= sizeof(long double)) {
 546           const RegisterInfo *f0_info = reg_ctx->GetRegisterInfoByName("f0", 0);
 547           RegisterValue f0_value;
 548           if (reg_ctx->ReadRegister(f0_info, f0_value)) {
 549             DataExtractor data;
 550             if (f0_value.GetData(data)) {
 551               lldb::offset_t offset = 0;
 552               if (*byte_size == sizeof(float)) {
 553                 value.GetScalar() = (float)data.GetFloat(&offset);
 554                 success = true;
 555               } else if (*byte_size == sizeof(double)) {
 556                 value.GetScalar() = (double)data.GetDouble(&offset);
 557                 success = true;
 558               } else if (*byte_size == sizeof(long double)) {
 559                 // Don't handle long double yet.
 560               }
 561             }
 562           }
 563         }
 564       }
 565     }
 566
 567     if (success)
 568       return_valobj_sp = ValueObjectConstResult::Create(
 569           thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));
 570   } else if (type_flags & eTypeIsPointer) {
 571     unsigned r2_id =
 572         reg_ctx->GetRegisterInfoByName("r2", 0)->kinds[eRegisterKindLLDB];
 573     value.GetScalar() =
 574         (uint64_t)thread.GetRegisterContext()->ReadRegisterAsUnsigned(r2_id, 0);
 575     value.SetValueType(Value::ValueType::Scalar);
 576     return_valobj_sp = ValueObjectConstResult::Create(
 577         thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));
 578   }
 579
 580   return return_valobj_sp;
 581 }
 582
 583 ValueObjectSP ABISysV_s390x::GetReturnValueObjectImpl(
 584     Thread &thread, CompilerType &return_compiler_type) const {
 585   ValueObjectSP return_valobj_sp;
 586
 587   if (!return_compiler_type)
 588     return return_valobj_sp;
 589
 590   ExecutionContext exe_ctx(thread.shared_from_this());
 591   return_valobj_sp = GetReturnValueObjectSimple(thread, return_compiler_type);
 592   if (return_valobj_sp)
 593     return return_valobj_sp;
 594
 595   RegisterContextSP reg_ctx_sp = thread.GetRegisterContext();
 596   if (!reg_ctx_sp)
 597     return return_valobj_sp;
 598
 599   if (return_compiler_type.IsAggregateType()) {
 600     // FIXME: This is just taking a guess, r2 may very well no longer hold the
 601     // return storage location.
 602     // If we are going to do this right, when we make a new frame we should
 603     // check to see if it uses a memory return, and if we are at the first
 604     // instruction and if so stash away the return location.  Then we would
 605     // only return the memory return value if we know it is valid.
 606
 607     unsigned r2_id =
 608         reg_ctx_sp->GetRegisterInfoByName("r2", 0)->kinds[eRegisterKindLLDB];
 609     lldb::addr_t storage_addr =
 610         (uint64_t)thread.GetRegisterContext()->ReadRegisterAsUnsigned(r2_id, 0);
 611     return_valobj_sp = ValueObjectMemory::Create(
 612         &thread, "", Address(storage_addr, nullptr), return_compiler_type);
 613   }
 614
 615   return return_valobj_sp;
 616 }
 617
 618 bool ABISysV_s390x::CreateFunctionEntryUnwindPlan(UnwindPlan &unwind_plan) {
 619   unwind_plan.Clear();
 620   unwind_plan.SetRegisterKind(eRegisterKindDWARF);
 621
 622   UnwindPlan::RowSP row(new UnwindPlan::Row);
 623
 624   // Our Call Frame Address is the stack pointer value + 160
 625   row->GetCFAValue().SetIsRegisterPlusOffset(dwarf_r15_s390x, 160);
 626
 627   // The previous PC is in r14
 628   row->SetRegisterLocationToRegister(dwarf_pswa_s390x, dwarf_r14_s390x, true);
 629
 630   // All other registers are the same.
 631   unwind_plan.AppendRow(row);
 632   unwind_plan.SetSourceName("s390x at-func-entry default");
 633   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
 634   return true;
 635 }
 636
 637 bool ABISysV_s390x::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
 638   // There's really no default way to unwind on s390x. Trust the .eh_frame CFI,
 639   // which should always be good.
 640   return false;
 641 }
 642
 643 bool ABISysV_s390x::GetFallbackRegisterLocation(
 644     const RegisterInfo *reg_info,
 645     UnwindPlan::Row::RegisterLocation &unwind_regloc) {
 646   // If a volatile register is being requested, we don't want to forward the
 647   // next frame's register contents up the stack -- the register is not
 648   // retrievable at this frame.
 649   if (RegisterIsVolatile(reg_info)) {
 650     unwind_regloc.SetUndefined();
 651     return true;
 652   }
 653
 654   return false;
 655 }
 656
 657 bool ABISysV_s390x::RegisterIsVolatile(const RegisterInfo *reg_info) {
 658   return !RegisterIsCalleeSaved(reg_info);
 659 }
 660
 661 bool ABISysV_s390x::RegisterIsCalleeSaved(const RegisterInfo *reg_info) {
 662   if (reg_info) {
 663     // Preserved registers are :
 664     //    r6-r13, r15
 665     //    f8-f15
 666
 667     const char *name = reg_info->name;
 668     if (name[0] == 'r') {
 669       switch (name[1]) {
 670       case '6': // r6
 671       case '7': // r7
 672       case '8': // r8
 673       case '9': // r9
 674         return name[2] == '\0';
 675
 676       case '1': // r10, r11, r12, r13, r15
 677         if ((name[2] >= '0' && name[2] <= '3') || name[2] == '5')
 678           return name[3] == '\0';
 679         break;
 680
 681       default:
 682         break;
 683       }
 684     }
 685     if (name[0] == 'f') {
 686       switch (name[1]) {
 687       case '8': // r8
 688       case '9': // r9
 689         return name[2] == '\0';
 690
 691       case '1': // r10, r11, r12, r13, r14, r15
 692         if (name[2] >= '0' && name[2] <= '5')
 693           return name[3] == '\0';
 694         break;
 695
 696       default:
 697         break;
 698       }
 699     }
 700
 701     // Accept shorter-variant versions
 702     if (name[0] == 's' && name[1] == 'p' && name[2] == '\0') // sp
 703       return true;
 704     if (name[0] == 'f' && name[1] == 'p' && name[2] == '\0') // fp
 705       return true;
 706     if (name[0] == 'p' && name[1] == 'c' && name[2] == '\0') // pc
 707       return true;
 708   }
 709   return false;
 710 }
 711
 712 void ABISysV_s390x::Initialize() {
 713   PluginManager::RegisterPlugin(
 714       GetPluginNameStatic(), "System V ABI for s390x targets", CreateInstance);
 715 }
 716
 717 void ABISysV_s390x::Terminate() {
 718   PluginManager::UnregisterPlugin(CreateInstance);
 719 }