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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "calling_convention_x86_64.h"
     18 
     19 #include "base/bit_utils.h"
     20 #include "base/logging.h"
     21 #include "handle_scope-inl.h"
     22 #include "utils/x86_64/managed_register_x86_64.h"
     23 
     24 namespace art {
     25 namespace x86_64 {
     26 
     27 constexpr size_t kFramePointerSize = static_cast<size_t>(PointerSize::k64);
     28 static_assert(kX86_64PointerSize == PointerSize::k64, "Unexpected x86_64 pointer size");
     29 static_assert(kStackAlignment >= 16u, "System V AMD64 ABI requires at least 16 byte stack alignment");
     30 
     31 // XMM0..XMM7 can be used to pass the first 8 floating args. The rest must go on the stack.
     32 // -- Managed and JNI calling conventions.
     33 constexpr size_t kMaxFloatOrDoubleRegisterArguments = 8u;
     34 // Up to how many integer-like (pointers, objects, longs, int, short, bool, etc) args can be
     35 // enregistered. The rest of the args must go on the stack.
     36 // -- JNI calling convention only (Managed excludes RDI, so it's actually 5).
     37 constexpr size_t kMaxIntLikeRegisterArguments = 6u;
     38 
     39 static constexpr ManagedRegister kCalleeSaveRegisters[] = {
     40     // Core registers.
     41     X86_64ManagedRegister::FromCpuRegister(RBX),
     42     X86_64ManagedRegister::FromCpuRegister(RBP),
     43     X86_64ManagedRegister::FromCpuRegister(R12),
     44     X86_64ManagedRegister::FromCpuRegister(R13),
     45     X86_64ManagedRegister::FromCpuRegister(R14),
     46     X86_64ManagedRegister::FromCpuRegister(R15),
     47     // Hard float registers.
     48     X86_64ManagedRegister::FromXmmRegister(XMM12),
     49     X86_64ManagedRegister::FromXmmRegister(XMM13),
     50     X86_64ManagedRegister::FromXmmRegister(XMM14),
     51     X86_64ManagedRegister::FromXmmRegister(XMM15),
     52 };
     53 
     54 static constexpr uint32_t CalculateCoreCalleeSpillMask() {
     55   // The spilled PC gets a special marker.
     56   uint32_t result = 1 << kNumberOfCpuRegisters;
     57   for (auto&& r : kCalleeSaveRegisters) {
     58     if (r.AsX86_64().IsCpuRegister()) {
     59       result |= (1 << r.AsX86_64().AsCpuRegister().AsRegister());
     60     }
     61   }
     62   return result;
     63 }
     64 
     65 static constexpr uint32_t CalculateFpCalleeSpillMask() {
     66   uint32_t result = 0;
     67   for (auto&& r : kCalleeSaveRegisters) {
     68     if (r.AsX86_64().IsXmmRegister()) {
     69       result |= (1 << r.AsX86_64().AsXmmRegister().AsFloatRegister());
     70     }
     71   }
     72   return result;
     73 }
     74 
     75 static constexpr uint32_t kCoreCalleeSpillMask = CalculateCoreCalleeSpillMask();
     76 static constexpr uint32_t kFpCalleeSpillMask = CalculateFpCalleeSpillMask();
     77 
     78 // Calling convention
     79 
     80 ManagedRegister X86_64ManagedRuntimeCallingConvention::InterproceduralScratchRegister() {
     81   return X86_64ManagedRegister::FromCpuRegister(RAX);
     82 }
     83 
     84 ManagedRegister X86_64JniCallingConvention::InterproceduralScratchRegister() {
     85   return X86_64ManagedRegister::FromCpuRegister(RAX);
     86 }
     87 
     88 ManagedRegister X86_64JniCallingConvention::ReturnScratchRegister() const {
     89   return ManagedRegister::NoRegister();  // No free regs, so assembler uses push/pop
     90 }
     91 
     92 static ManagedRegister ReturnRegisterForShorty(const char* shorty, bool jni ATTRIBUTE_UNUSED) {
     93   if (shorty[0] == 'F' || shorty[0] == 'D') {
     94     return X86_64ManagedRegister::FromXmmRegister(XMM0);
     95   } else if (shorty[0] == 'J') {
     96     return X86_64ManagedRegister::FromCpuRegister(RAX);
     97   } else if (shorty[0] == 'V') {
     98     return ManagedRegister::NoRegister();
     99   } else {
    100     return X86_64ManagedRegister::FromCpuRegister(RAX);
    101   }
    102 }
    103 
    104 ManagedRegister X86_64ManagedRuntimeCallingConvention::ReturnRegister() {
    105   return ReturnRegisterForShorty(GetShorty(), false);
    106 }
    107 
    108 ManagedRegister X86_64JniCallingConvention::ReturnRegister() {
    109   return ReturnRegisterForShorty(GetShorty(), true);
    110 }
    111 
    112 ManagedRegister X86_64JniCallingConvention::IntReturnRegister() {
    113   return X86_64ManagedRegister::FromCpuRegister(RAX);
    114 }
    115 
    116 // Managed runtime calling convention
    117 
    118 ManagedRegister X86_64ManagedRuntimeCallingConvention::MethodRegister() {
    119   return X86_64ManagedRegister::FromCpuRegister(RDI);
    120 }
    121 
    122 bool X86_64ManagedRuntimeCallingConvention::IsCurrentParamInRegister() {
    123   return !IsCurrentParamOnStack();
    124 }
    125 
    126 bool X86_64ManagedRuntimeCallingConvention::IsCurrentParamOnStack() {
    127   // We assume all parameters are on stack, args coming via registers are spilled as entry_spills
    128   return true;
    129 }
    130 
    131 ManagedRegister X86_64ManagedRuntimeCallingConvention::CurrentParamRegister() {
    132   ManagedRegister res = ManagedRegister::NoRegister();
    133   if (!IsCurrentParamAFloatOrDouble()) {
    134     switch (itr_args_ - itr_float_and_doubles_) {
    135     case 0: res = X86_64ManagedRegister::FromCpuRegister(RSI); break;
    136     case 1: res = X86_64ManagedRegister::FromCpuRegister(RDX); break;
    137     case 2: res = X86_64ManagedRegister::FromCpuRegister(RCX); break;
    138     case 3: res = X86_64ManagedRegister::FromCpuRegister(R8); break;
    139     case 4: res = X86_64ManagedRegister::FromCpuRegister(R9); break;
    140     }
    141   } else if (itr_float_and_doubles_ < kMaxFloatOrDoubleRegisterArguments) {
    142     // First eight float parameters are passed via XMM0..XMM7
    143     res = X86_64ManagedRegister::FromXmmRegister(
    144                                  static_cast<FloatRegister>(XMM0 + itr_float_and_doubles_));
    145   }
    146   return res;
    147 }
    148 
    149 FrameOffset X86_64ManagedRuntimeCallingConvention::CurrentParamStackOffset() {
    150   return FrameOffset(displacement_.Int32Value() +  // displacement
    151                      static_cast<size_t>(kX86_64PointerSize) +  // Method ref
    152                      itr_slots_ * sizeof(uint32_t));  // offset into in args
    153 }
    154 
    155 const ManagedRegisterEntrySpills& X86_64ManagedRuntimeCallingConvention::EntrySpills() {
    156   // We spill the argument registers on X86 to free them up for scratch use, we then assume
    157   // all arguments are on the stack.
    158   if (entry_spills_.size() == 0) {
    159     ResetIterator(FrameOffset(0));
    160     while (HasNext()) {
    161       ManagedRegister in_reg = CurrentParamRegister();
    162       if (!in_reg.IsNoRegister()) {
    163         int32_t size = IsParamALongOrDouble(itr_args_) ? 8 : 4;
    164         int32_t spill_offset = CurrentParamStackOffset().Uint32Value();
    165         ManagedRegisterSpill spill(in_reg, size, spill_offset);
    166         entry_spills_.push_back(spill);
    167       }
    168       Next();
    169     }
    170   }
    171   return entry_spills_;
    172 }
    173 
    174 // JNI calling convention
    175 
    176 X86_64JniCallingConvention::X86_64JniCallingConvention(bool is_static,
    177                                                        bool is_synchronized,
    178                                                        bool is_critical_native,
    179                                                        const char* shorty)
    180     : JniCallingConvention(is_static,
    181                            is_synchronized,
    182                            is_critical_native,
    183                            shorty,
    184                            kX86_64PointerSize) {
    185 }
    186 
    187 uint32_t X86_64JniCallingConvention::CoreSpillMask() const {
    188   return kCoreCalleeSpillMask;
    189 }
    190 
    191 uint32_t X86_64JniCallingConvention::FpSpillMask() const {
    192   return kFpCalleeSpillMask;
    193 }
    194 
    195 size_t X86_64JniCallingConvention::FrameSize() {
    196   // Method*, PC return address and callee save area size, local reference segment state
    197   const size_t method_ptr_size = static_cast<size_t>(kX86_64PointerSize);
    198   const size_t pc_return_addr_size = kFramePointerSize;
    199   const size_t callee_save_area_size = CalleeSaveRegisters().size() * kFramePointerSize;
    200   size_t frame_data_size = method_ptr_size + pc_return_addr_size + callee_save_area_size;
    201 
    202   if (LIKELY(HasLocalReferenceSegmentState())) {                     // local ref. segment state
    203     // Local reference segment state is sometimes excluded.
    204     frame_data_size += kFramePointerSize;
    205   }
    206 
    207   // References plus link_ (pointer) and number_of_references_ (uint32_t) for HandleScope header
    208   const size_t handle_scope_size = HandleScope::SizeOf(kX86_64PointerSize, ReferenceCount());
    209 
    210   size_t total_size = frame_data_size;
    211   if (LIKELY(HasHandleScope())) {
    212     // HandleScope is sometimes excluded.
    213     total_size += handle_scope_size;                                 // handle scope size
    214   }
    215 
    216   // Plus return value spill area size
    217   total_size += SizeOfReturnValue();
    218 
    219   return RoundUp(total_size, kStackAlignment);
    220 }
    221 
    222 size_t X86_64JniCallingConvention::OutArgSize() {
    223   return RoundUp(NumberOfOutgoingStackArgs() * kFramePointerSize, kStackAlignment);
    224 }
    225 
    226 ArrayRef<const ManagedRegister> X86_64JniCallingConvention::CalleeSaveRegisters() const {
    227   return ArrayRef<const ManagedRegister>(kCalleeSaveRegisters);
    228 }
    229 
    230 bool X86_64JniCallingConvention::IsCurrentParamInRegister() {
    231   return !IsCurrentParamOnStack();
    232 }
    233 
    234 bool X86_64JniCallingConvention::IsCurrentParamOnStack() {
    235   return CurrentParamRegister().IsNoRegister();
    236 }
    237 
    238 ManagedRegister X86_64JniCallingConvention::CurrentParamRegister() {
    239   ManagedRegister res = ManagedRegister::NoRegister();
    240   if (!IsCurrentParamAFloatOrDouble()) {
    241     switch (itr_args_ - itr_float_and_doubles_) {
    242     case 0: res = X86_64ManagedRegister::FromCpuRegister(RDI); break;
    243     case 1: res = X86_64ManagedRegister::FromCpuRegister(RSI); break;
    244     case 2: res = X86_64ManagedRegister::FromCpuRegister(RDX); break;
    245     case 3: res = X86_64ManagedRegister::FromCpuRegister(RCX); break;
    246     case 4: res = X86_64ManagedRegister::FromCpuRegister(R8); break;
    247     case 5: res = X86_64ManagedRegister::FromCpuRegister(R9); break;
    248     static_assert(5u == kMaxIntLikeRegisterArguments - 1, "Missing case statement(s)");
    249     }
    250   } else if (itr_float_and_doubles_ < kMaxFloatOrDoubleRegisterArguments) {
    251     // First eight float parameters are passed via XMM0..XMM7
    252     res = X86_64ManagedRegister::FromXmmRegister(
    253                                  static_cast<FloatRegister>(XMM0 + itr_float_and_doubles_));
    254   }
    255   return res;
    256 }
    257 
    258 FrameOffset X86_64JniCallingConvention::CurrentParamStackOffset() {
    259   CHECK(IsCurrentParamOnStack());
    260   size_t args_on_stack = itr_args_
    261       - std::min(kMaxFloatOrDoubleRegisterArguments,
    262                  static_cast<size_t>(itr_float_and_doubles_))
    263           // Float arguments passed through Xmm0..Xmm7
    264       - std::min(kMaxIntLikeRegisterArguments,
    265                  static_cast<size_t>(itr_args_ - itr_float_and_doubles_));
    266           // Integer arguments passed through GPR
    267   size_t offset = displacement_.Int32Value() - OutArgSize() + (args_on_stack * kFramePointerSize);
    268   CHECK_LT(offset, OutArgSize());
    269   return FrameOffset(offset);
    270 }
    271 
    272 // TODO: Calling this "NumberArgs" is misleading.
    273 // It's really more like NumberSlots (like itr_slots_)
    274 // because doubles/longs get counted twice.
    275 size_t X86_64JniCallingConvention::NumberOfOutgoingStackArgs() {
    276   size_t static_args = HasSelfClass() ? 1 : 0;  // count jclass
    277   // regular argument parameters and this
    278   size_t param_args = NumArgs() + NumLongOrDoubleArgs();
    279   // count JNIEnv* and return pc (pushed after Method*)
    280   size_t internal_args = 1 /* return pc */ + (HasJniEnv() ? 1 : 0 /* jni env */);
    281   size_t total_args = static_args + param_args + internal_args;
    282 
    283   // Float arguments passed through Xmm0..Xmm7
    284   // Other (integer) arguments passed through GPR (RDI, RSI, RDX, RCX, R8, R9)
    285   size_t total_stack_args = total_args
    286                             - std::min(kMaxFloatOrDoubleRegisterArguments, static_cast<size_t>(NumFloatOrDoubleArgs()))
    287                             - std::min(kMaxIntLikeRegisterArguments, static_cast<size_t>(NumArgs() - NumFloatOrDoubleArgs()));
    288 
    289   return total_stack_args;
    290 }
    291 
    292 }  // namespace x86_64
    293 }  // namespace art
    294