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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "art_method-inl.h"
#include "dex/code_item_accessors.h"
#include "entrypoints/quick/callee_save_frame.h"
#include "interpreter/mterp/nterp.h"
#include "nterp_helpers.h"
#include "oat_quick_method_header.h"
#include "quick/quick_method_frame_info.h"
namespace art {
/**
* An nterp frame follows the optimizing compiler's ABI conventions, with
* int/long/reference parameters being passed in core registers / stack and
* float/double parameters being passed in floating point registers / stack.
*
* There are no ManagedStack transitions between compiler and nterp frames.
*
* On entry, nterp will copy its parameters to a dex register array allocated on
* the stack. There is a fast path when calling from nterp to nterp to not
* follow the ABI but just copy the parameters from the caller's dex registers
* to the callee's dex registers.
*
* The stack layout of an nterp frame is:
* ----------------
* | | All callee save registers of the platform
* | callee-save | (core and floating point).
* | registers | On x86 and x64 this includes the return address,
* | | already spilled on entry.
* ----------------
* | alignment | Stack aligment of kStackAlignment.
* ----------------
* | | Contains `registers_size` entries (of size 4) from
* | dex | the code item information of the method.
* | registers |
* | |
* ----------------
* | | A copy of the dex registers above, but only
* | reference | containing references, used for GC.
* | registers |
* | |
* ----------------
* | caller fp | Frame pointer of caller. Stored below the reference
* ---------------- registers array for easy access from nterp when returning.
* | dex_pc_ptr | Pointer to the dex instruction being executed.
* ---------------- Stored whenever nterp goes into the runtime.
* | alignment | Pointer aligment for dex_pc_ptr and caller_fp.
* ----------------
* | | In case nterp calls compiled code, we reserve space
* | out | for out registers. This space will be used for
* | registers | arguments passed on stack.
* | |
* ----------------
* | ArtMethod* | The method being currently executed.
* ----------------
*
* Exception handling:
* Nterp follows the same convention than the compiler,
* with the addition of:
* - All catch handlers have the same landing pad.
* - Before doing the longjmp for exception delivery, the register containing the
* dex PC pointer must be updated.
*
* Stack walking:
* An nterp frame is walked like a compiled code frame. We add an
* OatQuickMethodHeader prefix to the nterp entry point, which contains:
* - vmap_table_offset=0 (nterp doesn't need one).
* - code_size=NterpEnd-NterpStart
*/
static constexpr size_t kPointerSize = static_cast<size_t>(kRuntimePointerSize);
static constexpr size_t NterpGetFrameEntrySize(InstructionSet isa) {
uint32_t core_spills = 0;
uint32_t fp_spills = 0;
// Note: the return address is considered part of the callee saves.
switch (isa) {
case InstructionSet::kX86:
core_spills = x86::X86CalleeSaveFrame::GetCoreSpills(CalleeSaveType::kSaveAllCalleeSaves);
fp_spills = x86::X86CalleeSaveFrame::GetFpSpills(CalleeSaveType::kSaveAllCalleeSaves);
break;
case InstructionSet::kX86_64:
core_spills =
x86_64::X86_64CalleeSaveFrame::GetCoreSpills(CalleeSaveType::kSaveAllCalleeSaves);
fp_spills = x86_64::X86_64CalleeSaveFrame::GetFpSpills(CalleeSaveType::kSaveAllCalleeSaves);
break;
case InstructionSet::kArm:
case InstructionSet::kThumb2:
core_spills = arm::ArmCalleeSaveFrame::GetCoreSpills(CalleeSaveType::kSaveAllCalleeSaves);
fp_spills = arm::ArmCalleeSaveFrame::GetFpSpills(CalleeSaveType::kSaveAllCalleeSaves);
break;
case InstructionSet::kArm64:
core_spills = arm64::Arm64CalleeSaveFrame::GetCoreSpills(CalleeSaveType::kSaveAllCalleeSaves);
fp_spills = arm64::Arm64CalleeSaveFrame::GetFpSpills(CalleeSaveType::kSaveAllCalleeSaves);
break;
default:
InstructionSetAbort(isa);
}
// Note: the return address is considered part of the callee saves.
return (POPCOUNT(core_spills) + POPCOUNT(fp_spills)) *
static_cast<size_t>(InstructionSetPointerSize(isa));
}
size_t NterpGetFrameSize(ArtMethod* method, InstructionSet isa) {
CodeItemDataAccessor accessor(method->DexInstructionData());
const uint16_t num_regs = accessor.RegistersSize();
const uint16_t out_regs = accessor.OutsSize();
size_t pointer_size = static_cast<size_t>(InstructionSetPointerSize(isa));
// Note: There may be two pieces of alignment but there is no need to align
// out args to `kPointerSize` separately before aligning to kStackAlignment.
DCHECK(IsAlignedParam(kStackAlignment, pointer_size));
DCHECK(IsAlignedParam(NterpGetFrameEntrySize(isa), pointer_size));
DCHECK(IsAlignedParam(kVRegSize * 2, pointer_size));
size_t frame_size =
NterpGetFrameEntrySize(isa) +
(num_regs * kVRegSize) * 2 + // dex registers and reference registers
pointer_size + // previous frame
pointer_size + // saved dex pc
(out_regs * kVRegSize) + // out arguments
pointer_size; // method
return RoundUp(frame_size, kStackAlignment);
}
QuickMethodFrameInfo NterpFrameInfo(ArtMethod** frame) {
uint32_t core_spills =
RuntimeCalleeSaveFrame::GetCoreSpills(CalleeSaveType::kSaveAllCalleeSaves);
uint32_t fp_spills =
RuntimeCalleeSaveFrame::GetFpSpills(CalleeSaveType::kSaveAllCalleeSaves);
return QuickMethodFrameInfo(NterpGetFrameSize(*frame), core_spills, fp_spills);
}
uintptr_t NterpGetRegistersArray(ArtMethod** frame) {
CodeItemDataAccessor accessor((*frame)->DexInstructionData());
const uint16_t num_regs = accessor.RegistersSize();
// The registers array is just above the reference array.
return NterpGetReferenceArray(frame) + (num_regs * kVRegSize);
}
uintptr_t NterpGetReferenceArray(ArtMethod** frame) {
CodeItemDataAccessor accessor((*frame)->DexInstructionData());
const uint16_t out_regs = accessor.OutsSize();
// The references array is just above the saved frame pointer.
return reinterpret_cast<uintptr_t>(frame) +
kPointerSize + // method
RoundUp(out_regs * kVRegSize, kPointerSize) + // out arguments and pointer alignment
kPointerSize + // saved dex pc
kPointerSize; // previous frame.
}
uint32_t NterpGetDexPC(ArtMethod** frame) {
CodeItemDataAccessor accessor((*frame)->DexInstructionData());
const uint16_t out_regs = accessor.OutsSize();
uintptr_t dex_pc_ptr = reinterpret_cast<uintptr_t>(frame) +
kPointerSize + // method
RoundUp(out_regs * kVRegSize, kPointerSize); // out arguments and pointer alignment
CodeItemInstructionAccessor instructions((*frame)->DexInstructions());
return *reinterpret_cast<const uint16_t**>(dex_pc_ptr) - instructions.Insns();
}
uint32_t NterpGetVReg(ArtMethod** frame, uint16_t vreg) {
return reinterpret_cast<uint32_t*>(NterpGetRegistersArray(frame))[vreg];
}
uint32_t NterpGetVRegReference(ArtMethod** frame, uint16_t vreg) {
return reinterpret_cast<uint32_t*>(NterpGetReferenceArray(frame))[vreg];
}
uintptr_t NterpGetCatchHandler() {
// Nterp uses the same landing pad for all exceptions. The dex_pc_ptr set before
// longjmp will actually be used to jmp to the catch handler.
return reinterpret_cast<uintptr_t>(artNterpAsmInstructionEnd);
}
bool CanMethodUseNterp(ArtMethod* method, InstructionSet isa) {
return !method->IsNative() &&
method->IsInvokable() &&
// Nterp supports the same methods the compiler supports.
method->IsCompilable() &&
!method->MustCountLocks() &&
// Proxy methods do not go through the JIT like other methods, so we don't
// run them with nterp.
!method->IsProxyMethod() &&
NterpGetFrameSize(method, isa) <= interpreter::kNterpMaxFrame;
}
} // namespace art
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