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/*
* Copyright (C) 2011 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.
*/
/* This file contains codegen for the Thumb2 ISA. */
#include "arm_lir.h"
#include "codegen_arm.h"
#include "dex/quick/mir_to_lir-inl.h"
#include "entrypoints/quick/quick_entrypoints.h"
namespace art {
/*
* The sparse table in the literal pool is an array of <key,displacement>
* pairs. For each set, we'll load them as a pair using ldmia.
* This means that the register number of the temp we use for the key
* must be lower than the reg for the displacement.
*
* The test loop will look something like:
*
* adr rBase, <table>
* ldr r_val, [rARM_SP, v_reg_off]
* mov r_idx, #table_size
* lp:
* ldmia rBase!, {r_key, r_disp}
* sub r_idx, #1
* cmp r_val, r_key
* ifeq
* add rARM_PC, r_disp ; This is the branch from which we compute displacement
* cbnz r_idx, lp
*/
void ArmMir2Lir::GenSparseSwitch(MIR* mir, uint32_t table_offset,
RegLocation rl_src) {
const uint16_t* table = cu_->insns + current_dalvik_offset_ + table_offset;
if (cu_->verbose) {
DumpSparseSwitchTable(table);
}
// Add the table to the list - we'll process it later
SwitchTable *tab_rec =
static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
tab_rec->table = table;
tab_rec->vaddr = current_dalvik_offset_;
uint32_t size = table[1];
tab_rec->targets = static_cast<LIR**>(arena_->Alloc(size * sizeof(LIR*),
kArenaAllocLIR));
switch_tables_.Insert(tab_rec);
// Get the switch value
rl_src = LoadValue(rl_src, kCoreReg);
int rBase = AllocTemp();
/* Allocate key and disp temps */
int r_key = AllocTemp();
int r_disp = AllocTemp();
// Make sure r_key's register number is less than r_disp's number for ldmia
if (r_key > r_disp) {
int tmp = r_disp;
r_disp = r_key;
r_key = tmp;
}
// Materialize a pointer to the switch table
NewLIR3(kThumb2Adr, rBase, 0, WrapPointer(tab_rec));
// Set up r_idx
int r_idx = AllocTemp();
LoadConstant(r_idx, size);
// Establish loop branch target
LIR* target = NewLIR0(kPseudoTargetLabel);
// Load next key/disp
NewLIR2(kThumb2LdmiaWB, rBase, (1 << r_key) | (1 << r_disp));
OpRegReg(kOpCmp, r_key, rl_src.reg.GetReg());
// Go if match. NOTE: No instruction set switch here - must stay Thumb2
OpIT(kCondEq, "");
LIR* switch_branch = NewLIR1(kThumb2AddPCR, r_disp);
tab_rec->anchor = switch_branch;
// Needs to use setflags encoding here
OpRegRegImm(kOpSub, r_idx, r_idx, 1); // For value == 1, this should set flags.
DCHECK(last_lir_insn_->u.m.def_mask & ENCODE_CCODE);
OpCondBranch(kCondNe, target);
}
void ArmMir2Lir::GenPackedSwitch(MIR* mir, uint32_t table_offset,
RegLocation rl_src) {
const uint16_t* table = cu_->insns + current_dalvik_offset_ + table_offset;
if (cu_->verbose) {
DumpPackedSwitchTable(table);
}
// Add the table to the list - we'll process it later
SwitchTable *tab_rec =
static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
tab_rec->table = table;
tab_rec->vaddr = current_dalvik_offset_;
uint32_t size = table[1];
tab_rec->targets =
static_cast<LIR**>(arena_->Alloc(size * sizeof(LIR*), kArenaAllocLIR));
switch_tables_.Insert(tab_rec);
// Get the switch value
rl_src = LoadValue(rl_src, kCoreReg);
int table_base = AllocTemp();
// Materialize a pointer to the switch table
NewLIR3(kThumb2Adr, table_base, 0, WrapPointer(tab_rec));
int low_key = s4FromSwitchData(&table[2]);
int keyReg;
// Remove the bias, if necessary
if (low_key == 0) {
keyReg = rl_src.reg.GetReg();
} else {
keyReg = AllocTemp();
OpRegRegImm(kOpSub, keyReg, rl_src.reg.GetReg(), low_key);
}
// Bounds check - if < 0 or >= size continue following switch
OpRegImm(kOpCmp, keyReg, size-1);
LIR* branch_over = OpCondBranch(kCondHi, NULL);
// Load the displacement from the switch table
int disp_reg = AllocTemp();
LoadBaseIndexed(table_base, keyReg, disp_reg, 2, kWord);
// ..and go! NOTE: No instruction set switch here - must stay Thumb2
LIR* switch_branch = NewLIR1(kThumb2AddPCR, disp_reg);
tab_rec->anchor = switch_branch;
/* branch_over target here */
LIR* target = NewLIR0(kPseudoTargetLabel);
branch_over->target = target;
}
/*
* Array data table format:
* ushort ident = 0x0300 magic value
* ushort width width of each element in the table
* uint size number of elements in the table
* ubyte data[size*width] table of data values (may contain a single-byte
* padding at the end)
*
* Total size is 4+(width * size + 1)/2 16-bit code units.
*/
void ArmMir2Lir::GenFillArrayData(uint32_t table_offset, RegLocation rl_src) {
const uint16_t* table = cu_->insns + current_dalvik_offset_ + table_offset;
// Add the table to the list - we'll process it later
FillArrayData *tab_rec =
static_cast<FillArrayData*>(arena_->Alloc(sizeof(FillArrayData), kArenaAllocData));
tab_rec->table = table;
tab_rec->vaddr = current_dalvik_offset_;
uint16_t width = tab_rec->table[1];
uint32_t size = tab_rec->table[2] | ((static_cast<uint32_t>(tab_rec->table[3])) << 16);
tab_rec->size = (size * width) + 8;
fill_array_data_.Insert(tab_rec);
// Making a call - use explicit registers
FlushAllRegs(); /* Everything to home location */
LoadValueDirectFixed(rl_src, r0);
LoadWordDisp(rARM_SELF, QUICK_ENTRYPOINT_OFFSET(pHandleFillArrayData).Int32Value(),
rARM_LR);
// Materialize a pointer to the fill data image
NewLIR3(kThumb2Adr, r1, 0, WrapPointer(tab_rec));
ClobberCallerSave();
LIR* call_inst = OpReg(kOpBlx, rARM_LR);
MarkSafepointPC(call_inst);
}
/*
* Handle unlocked -> thin locked transition inline or else call out to quick entrypoint. For more
* details see monitor.cc.
*/
void ArmMir2Lir::GenMonitorEnter(int opt_flags, RegLocation rl_src) {
FlushAllRegs();
LoadValueDirectFixed(rl_src, r0); // Get obj
LockCallTemps(); // Prepare for explicit register usage
constexpr bool kArchVariantHasGoodBranchPredictor = false; // TODO: true if cortex-A15.
if (kArchVariantHasGoodBranchPredictor) {
LIR* null_check_branch;
if ((opt_flags & MIR_IGNORE_NULL_CHECK) && !(cu_->disable_opt & (1 << kNullCheckElimination))) {
null_check_branch = nullptr; // No null check.
} else {
// If the null-check fails its handled by the slow-path to reduce exception related meta-data.
null_check_branch = OpCmpImmBranch(kCondEq, r0, 0, NULL);
}
LoadWordDisp(rARM_SELF, Thread::ThinLockIdOffset().Int32Value(), r2);
NewLIR3(kThumb2Ldrex, r1, r0, mirror::Object::MonitorOffset().Int32Value() >> 2);
LIR* not_unlocked_branch = OpCmpImmBranch(kCondNe, r1, 0, NULL);
NewLIR4(kThumb2Strex, r1, r2, r0, mirror::Object::MonitorOffset().Int32Value() >> 2);
LIR* lock_success_branch = OpCmpImmBranch(kCondEq, r1, 0, NULL);
LIR* slow_path_target = NewLIR0(kPseudoTargetLabel);
not_unlocked_branch->target = slow_path_target;
if (null_check_branch != nullptr) {
null_check_branch->target = slow_path_target;
}
// TODO: move to a slow path.
// Go expensive route - artLockObjectFromCode(obj);
LoadWordDisp(rARM_SELF, QUICK_ENTRYPOINT_OFFSET(pLockObject).Int32Value(), rARM_LR);
ClobberCallerSave();
LIR* call_inst = OpReg(kOpBlx, rARM_LR);
MarkSafepointPC(call_inst);
LIR* success_target = NewLIR0(kPseudoTargetLabel);
lock_success_branch->target = success_target;
GenMemBarrier(kLoadLoad);
} else {
// Explicit null-check as slow-path is entered using an IT.
GenNullCheck(r0, opt_flags);
LoadWordDisp(rARM_SELF, Thread::ThinLockIdOffset().Int32Value(), r2);
MarkPossibleNullPointerException(opt_flags);
NewLIR3(kThumb2Ldrex, r1, r0, mirror::Object::MonitorOffset().Int32Value() >> 2);
OpRegImm(kOpCmp, r1, 0);
OpIT(kCondEq, "");
NewLIR4(kThumb2Strex/*eq*/, r1, r2, r0, mirror::Object::MonitorOffset().Int32Value() >> 2);
OpRegImm(kOpCmp, r1, 0);
OpIT(kCondNe, "T");
// Go expensive route - artLockObjectFromCode(self, obj);
LoadWordDisp/*ne*/(rARM_SELF, QUICK_ENTRYPOINT_OFFSET(pLockObject).Int32Value(), rARM_LR);
ClobberCallerSave();
LIR* call_inst = OpReg(kOpBlx/*ne*/, rARM_LR);
MarkSafepointPC(call_inst);
GenMemBarrier(kLoadLoad);
}
}
/*
* Handle thin locked -> unlocked transition inline or else call out to quick entrypoint. For more
* details see monitor.cc. Note the code below doesn't use ldrex/strex as the code holds the lock
* and can only give away ownership if its suspended.
*/
void ArmMir2Lir::GenMonitorExit(int opt_flags, RegLocation rl_src) {
FlushAllRegs();
LoadValueDirectFixed(rl_src, r0); // Get obj
LockCallTemps(); // Prepare for explicit register usage
LIR* null_check_branch;
LoadWordDisp(rARM_SELF, Thread::ThinLockIdOffset().Int32Value(), r2);
constexpr bool kArchVariantHasGoodBranchPredictor = false; // TODO: true if cortex-A15.
if (kArchVariantHasGoodBranchPredictor) {
if ((opt_flags & MIR_IGNORE_NULL_CHECK) && !(cu_->disable_opt & (1 << kNullCheckElimination))) {
null_check_branch = nullptr; // No null check.
} else {
// If the null-check fails its handled by the slow-path to reduce exception related meta-data.
null_check_branch = OpCmpImmBranch(kCondEq, r0, 0, NULL);
}
LoadWordDisp(r0, mirror::Object::MonitorOffset().Int32Value(), r1);
LoadConstantNoClobber(r3, 0);
LIR* slow_unlock_branch = OpCmpBranch(kCondNe, r1, r2, NULL);
StoreWordDisp(r0, mirror::Object::MonitorOffset().Int32Value(), r3);
LIR* unlock_success_branch = OpUnconditionalBranch(NULL);
LIR* slow_path_target = NewLIR0(kPseudoTargetLabel);
slow_unlock_branch->target = slow_path_target;
if (null_check_branch != nullptr) {
null_check_branch->target = slow_path_target;
}
// TODO: move to a slow path.
// Go expensive route - artUnlockObjectFromCode(obj);
LoadWordDisp(rARM_SELF, QUICK_ENTRYPOINT_OFFSET(pUnlockObject).Int32Value(), rARM_LR);
ClobberCallerSave();
LIR* call_inst = OpReg(kOpBlx, rARM_LR);
MarkSafepointPC(call_inst);
LIR* success_target = NewLIR0(kPseudoTargetLabel);
unlock_success_branch->target = success_target;
GenMemBarrier(kStoreLoad);
} else {
// Explicit null-check as slow-path is entered using an IT.
GenNullCheck(r0, opt_flags);
LoadWordDisp(r0, mirror::Object::MonitorOffset().Int32Value(), r1); // Get lock
MarkPossibleNullPointerException(opt_flags);
LoadWordDisp(rARM_SELF, Thread::ThinLockIdOffset().Int32Value(), r2);
LoadConstantNoClobber(r3, 0);
// Is lock unheld on lock or held by us (==thread_id) on unlock?
OpRegReg(kOpCmp, r1, r2);
OpIT(kCondEq, "EE");
StoreWordDisp/*eq*/(r0, mirror::Object::MonitorOffset().Int32Value(), r3);
// Go expensive route - UnlockObjectFromCode(obj);
LoadWordDisp/*ne*/(rARM_SELF, QUICK_ENTRYPOINT_OFFSET(pUnlockObject).Int32Value(), rARM_LR);
ClobberCallerSave();
LIR* call_inst = OpReg(kOpBlx/*ne*/, rARM_LR);
MarkSafepointPC(call_inst);
GenMemBarrier(kStoreLoad);
}
}
void ArmMir2Lir::GenMoveException(RegLocation rl_dest) {
int ex_offset = Thread::ExceptionOffset().Int32Value();
RegLocation rl_result = EvalLoc(rl_dest, kCoreReg, true);
int reset_reg = AllocTemp();
LoadWordDisp(rARM_SELF, ex_offset, rl_result.reg.GetReg());
LoadConstant(reset_reg, 0);
StoreWordDisp(rARM_SELF, ex_offset, reset_reg);
FreeTemp(reset_reg);
StoreValue(rl_dest, rl_result);
}
/*
* Mark garbage collection card. Skip if the value we're storing is null.
*/
void ArmMir2Lir::MarkGCCard(int val_reg, int tgt_addr_reg) {
int reg_card_base = AllocTemp();
int reg_card_no = AllocTemp();
LIR* branch_over = OpCmpImmBranch(kCondEq, val_reg, 0, NULL);
LoadWordDisp(rARM_SELF, Thread::CardTableOffset().Int32Value(), reg_card_base);
OpRegRegImm(kOpLsr, reg_card_no, tgt_addr_reg, gc::accounting::CardTable::kCardShift);
StoreBaseIndexed(reg_card_base, reg_card_no, reg_card_base, 0,
kUnsignedByte);
LIR* target = NewLIR0(kPseudoTargetLabel);
branch_over->target = target;
FreeTemp(reg_card_base);
FreeTemp(reg_card_no);
}
void ArmMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method) {
int spill_count = num_core_spills_ + num_fp_spills_;
/*
* On entry, r0, r1, r2 & r3 are live. Let the register allocation
* mechanism know so it doesn't try to use any of them when
* expanding the frame or flushing. This leaves the utility
* code with a single temp: r12. This should be enough.
*/
LockTemp(r0);
LockTemp(r1);
LockTemp(r2);
LockTemp(r3);
/*
* We can safely skip the stack overflow check if we're
* a leaf *and* our frame size < fudge factor.
*/
bool skip_overflow_check = (mir_graph_->MethodIsLeaf() &&
(static_cast<size_t>(frame_size_) <
Thread::kStackOverflowReservedBytes));
NewLIR0(kPseudoMethodEntry);
if (!skip_overflow_check) {
if (Runtime::Current()->ExplicitStackOverflowChecks()) {
/* Load stack limit */
LoadWordDisp(rARM_SELF, Thread::StackEndOffset().Int32Value(), r12);
}
}
/* Spill core callee saves */
NewLIR1(kThumb2Push, core_spill_mask_);
/* Need to spill any FP regs? */
if (num_fp_spills_) {
/*
* NOTE: fp spills are a little different from core spills in that
* they are pushed as a contiguous block. When promoting from
* the fp set, we must allocate all singles from s16..highest-promoted
*/
NewLIR1(kThumb2VPushCS, num_fp_spills_);
}
if (!skip_overflow_check) {
if (Runtime::Current()->ExplicitStackOverflowChecks()) {
OpRegRegImm(kOpSub, rARM_LR, rARM_SP, frame_size_ - (spill_count * 4));
GenRegRegCheck(kCondUlt, rARM_LR, r12, kThrowStackOverflow);
OpRegCopy(rARM_SP, rARM_LR); // Establish stack
} else {
// Implicit stack overflow check.
// Generate a load from [sp, #-framesize]. If this is in the stack
// redzone we will get a segmentation fault.
uint32_t full_frame_size = frame_size_ - (spill_count * 4);
OpRegImm(kOpSub, rARM_SP, full_frame_size);
LoadWordDisp(rARM_SP, 0, rARM_LR);
MarkPossibleStackOverflowException();
}
} else {
OpRegImm(kOpSub, rARM_SP, frame_size_ - (spill_count * 4));
}
FlushIns(ArgLocs, rl_method);
FreeTemp(r0);
FreeTemp(r1);
FreeTemp(r2);
FreeTemp(r3);
}
void ArmMir2Lir::GenExitSequence() {
int spill_count = num_core_spills_ + num_fp_spills_;
/*
* In the exit path, r0/r1 are live - make sure they aren't
* allocated by the register utilities as temps.
*/
LockTemp(r0);
LockTemp(r1);
NewLIR0(kPseudoMethodExit);
OpRegImm(kOpAdd, rARM_SP, frame_size_ - (spill_count * 4));
/* Need to restore any FP callee saves? */
if (num_fp_spills_) {
NewLIR1(kThumb2VPopCS, num_fp_spills_);
}
if (core_spill_mask_ & (1 << rARM_LR)) {
/* Unspill rARM_LR to rARM_PC */
core_spill_mask_ &= ~(1 << rARM_LR);
core_spill_mask_ |= (1 << rARM_PC);
}
NewLIR1(kThumb2Pop, core_spill_mask_);
if (!(core_spill_mask_ & (1 << rARM_PC))) {
/* We didn't pop to rARM_PC, so must do a bv rARM_LR */
NewLIR1(kThumbBx, rARM_LR);
}
}
void ArmMir2Lir::GenSpecialExitSequence() {
NewLIR1(kThumbBx, rARM_LR);
}
} // namespace art