/*
* Copyright (C) 2012 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 Mips ISA */
#include "codegen_mips.h"
#include "dex/quick/mir_to_lir-inl.h"
#include "entrypoints/quick/quick_entrypoints.h"
#include "gc/accounting/card_table.h"
#include "mips_lir.h"
namespace art {
bool MipsMir2Lir::GenSpecialCase(BasicBlock* bb, MIR* mir,
const InlineMethod& special) {
// TODO
return false;
}
/*
* The lack of pc-relative loads on Mips presents somewhat of a challenge
* for our PIC switch table strategy. To materialize the current location
* we'll do a dummy JAL and reference our tables using rRA as the
* base register. Note that rRA will be used both as the base to
* locate the switch table data and as the reference base for the switch
* target offsets stored in the table. We'll use a special pseudo-instruction
* to represent the jal and trigger the construction of the
* switch table offsets (which will happen after final assembly and all
* labels are fixed).
*
* The test loop will look something like:
*
* ori r_end, rZERO, #table_size ; size in bytes
* jal BaseLabel ; stores "return address" (BaseLabel) in rRA
* nop ; opportunistically fill
* BaseLabel:
* addiu r_base, rRA, <table> - <BaseLabel> ; table relative to BaseLabel
addu r_end, r_end, r_base ; end of table
* lw r_val, [rSP, v_reg_off] ; Test Value
* loop:
* beq r_base, r_end, done
* lw r_key, 0(r_base)
* addu r_base, 8
* bne r_val, r_key, loop
* lw r_disp, -4(r_base)
* addu rRA, r_disp
* jr rRA
* done:
*
*/
void MipsMir2Lir::GenLargeSparseSwitch(MIR* mir, DexOffset 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_;
int elements = table[1];
tab_rec->targets =
static_cast<LIR**>(arena_->Alloc(elements * sizeof(LIR*), kArenaAllocLIR));
switch_tables_.Insert(tab_rec);
// The table is composed of 8-byte key/disp pairs
int byte_size = elements * 8;
int size_hi = byte_size >> 16;
int size_lo = byte_size & 0xffff;
RegStorage r_end = AllocTemp();
if (size_hi) {
NewLIR2(kMipsLui, r_end.GetReg(), size_hi);
}
// Must prevent code motion for the curr pc pair
GenBarrier(); // Scheduling barrier
NewLIR0(kMipsCurrPC); // Really a jal to .+8
// Now, fill the branch delay slot
if (size_hi) {
NewLIR3(kMipsOri, r_end.GetReg(), r_end.GetReg(), size_lo);
} else {
NewLIR3(kMipsOri, r_end.GetReg(), rZERO, size_lo);
}
GenBarrier(); // Scheduling barrier
// Construct BaseLabel and set up table base register
LIR* base_label = NewLIR0(kPseudoTargetLabel);
// Remember base label so offsets can be computed later
tab_rec->anchor = base_label;
RegStorage r_base = AllocTemp();
NewLIR4(kMipsDelta, r_base.GetReg(), 0, WrapPointer(base_label), WrapPointer(tab_rec));
OpRegRegReg(kOpAdd, r_end, r_end, r_base);
// Grab switch test value
rl_src = LoadValue(rl_src, kCoreReg);
// Test loop
RegStorage r_key = AllocTemp();
LIR* loop_label = NewLIR0(kPseudoTargetLabel);
LIR* exit_branch = OpCmpBranch(kCondEq, r_base, r_end, NULL);
Load32Disp(r_base, 0, r_key);
OpRegImm(kOpAdd, r_base, 8);
OpCmpBranch(kCondNe, rl_src.reg, r_key, loop_label);
RegStorage r_disp = AllocTemp();
Load32Disp(r_base, -4, r_disp);
OpRegRegReg(kOpAdd, rs_rRA, rs_rRA, r_disp);
OpReg(kOpBx, rs_rRA);
// Loop exit
LIR* exit_label = NewLIR0(kPseudoTargetLabel);
exit_branch->target = exit_label;
}
/*
* Code pattern will look something like:
*
* lw r_val
* jal BaseLabel ; stores "return address" (BaseLabel) in rRA
* nop ; opportunistically fill
* [subiu r_val, bias] ; Remove bias if low_val != 0
* bound check -> done
* lw r_disp, [rRA, r_val]
* addu rRA, r_disp
* jr rRA
* done:
*/
void MipsMir2Lir::GenLargePackedSwitch(MIR* mir, DexOffset 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_;
int 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);
// Prepare the bias. If too big, handle 1st stage here
int low_key = s4FromSwitchData(&table[2]);
bool large_bias = false;
RegStorage r_key;
if (low_key == 0) {
r_key = rl_src.reg;
} else if ((low_key & 0xffff) != low_key) {
r_key = AllocTemp();
LoadConstant(r_key, low_key);
large_bias = true;
} else {
r_key = AllocTemp();
}
// Must prevent code motion for the curr pc pair
GenBarrier();
NewLIR0(kMipsCurrPC); // Really a jal to .+8
// Now, fill the branch delay slot with bias strip
if (low_key == 0) {
NewLIR0(kMipsNop);
} else {
if (large_bias) {
OpRegRegReg(kOpSub, r_key, rl_src.reg, r_key);
} else {
OpRegRegImm(kOpSub, r_key, rl_src.reg, low_key);
}
}
GenBarrier(); // Scheduling barrier
// Construct BaseLabel and set up table base register
LIR* base_label = NewLIR0(kPseudoTargetLabel);
// Remember base label so offsets can be computed later
tab_rec->anchor = base_label;
// Bounds check - if < 0 or >= size continue following switch
LIR* branch_over = OpCmpImmBranch(kCondHi, r_key, size-1, NULL);
// Materialize the table base pointer
RegStorage r_base = AllocTemp();
NewLIR4(kMipsDelta, r_base.GetReg(), 0, WrapPointer(base_label), WrapPointer(tab_rec));
// Load the displacement from the switch table
RegStorage r_disp = AllocTemp();
LoadBaseIndexed(r_base, r_key, r_disp, 2, k32);
// Add to rAP and go
OpRegRegReg(kOpAdd, rs_rRA, rs_rRA, r_disp);
OpReg(kOpBx, rs_rRA);
/* 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 MipsMir2Lir::GenFillArrayData(DexOffset 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 =
reinterpret_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 */
LockCallTemps();
LoadValueDirectFixed(rl_src, rs_rMIPS_ARG0);
// Must prevent code motion for the curr pc pair
GenBarrier();
NewLIR0(kMipsCurrPC); // Really a jal to .+8
// Now, fill the branch delay slot with the helper load
RegStorage r_tgt = LoadHelper(kQuickHandleFillArrayData);
GenBarrier(); // Scheduling barrier
// Construct BaseLabel and set up table base register
LIR* base_label = NewLIR0(kPseudoTargetLabel);
// Materialize a pointer to the fill data image
NewLIR4(kMipsDelta, rMIPS_ARG1, 0, WrapPointer(base_label), WrapPointer(tab_rec));
// And go...
ClobberCallerSave();
LIR* call_inst = OpReg(kOpBlx, r_tgt); // ( array*, fill_data* )
MarkSafepointPC(call_inst);
}
void MipsMir2Lir::GenMoveException(RegLocation rl_dest) {
int ex_offset = Thread::ExceptionOffset<4>().Int32Value();
RegLocation rl_result = EvalLoc(rl_dest, kRefReg, true);
RegStorage reset_reg = AllocTempRef();
LoadRefDisp(rs_rMIPS_SELF, ex_offset, rl_result.reg, kNotVolatile);
LoadConstant(reset_reg, 0);
StoreRefDisp(rs_rMIPS_SELF, ex_offset, reset_reg, kNotVolatile);
FreeTemp(reset_reg);
StoreValue(rl_dest, rl_result);
}
/*
* Mark garbage collection card. Skip if the value we're storing is null.
*/
void MipsMir2Lir::MarkGCCard(RegStorage val_reg, RegStorage tgt_addr_reg) {
RegStorage reg_card_base = AllocTemp();
RegStorage reg_card_no = AllocTemp();
LIR* branch_over = OpCmpImmBranch(kCondEq, val_reg, 0, NULL);
// NOTE: native pointer.
LoadWordDisp(rs_rMIPS_SELF, Thread::CardTableOffset<4>().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 MipsMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method) {
int spill_count = num_core_spills_ + num_fp_spills_;
/*
* On entry, rMIPS_ARG0, rMIPS_ARG1, rMIPS_ARG2 & rMIPS_ARG3 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(rs_rMIPS_ARG0);
LockTemp(rs_rMIPS_ARG1);
LockTemp(rs_rMIPS_ARG2);
LockTemp(rs_rMIPS_ARG3);
/*
* 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() && !FrameNeedsStackCheck(frame_size_, kMips);
NewLIR0(kPseudoMethodEntry);
RegStorage check_reg = AllocTemp();
RegStorage new_sp = AllocTemp();
if (!skip_overflow_check) {
/* Load stack limit */
Load32Disp(rs_rMIPS_SELF, Thread::StackEndOffset<4>().Int32Value(), check_reg);
}
/* Spill core callee saves */
SpillCoreRegs();
/* NOTE: promotion of FP regs currently unsupported, thus no FP spill */
DCHECK_EQ(num_fp_spills_, 0);
const int frame_sub = frame_size_ - spill_count * 4;
if (!skip_overflow_check) {
class StackOverflowSlowPath : public LIRSlowPath {
public:
StackOverflowSlowPath(Mir2Lir* m2l, LIR* branch, size_t sp_displace)
: LIRSlowPath(m2l, m2l->GetCurrentDexPc(), branch, nullptr), sp_displace_(sp_displace) {
}
void Compile() OVERRIDE {
m2l_->ResetRegPool();
m2l_->ResetDefTracking();
GenerateTargetLabel(kPseudoThrowTarget);
// LR is offset 0 since we push in reverse order.
m2l_->Load32Disp(rs_rMIPS_SP, 0, rs_rRA);
m2l_->OpRegImm(kOpAdd, rs_rMIPS_SP, sp_displace_);
m2l_->ClobberCallerSave();
RegStorage r_tgt = m2l_->CallHelperSetup(kQuickThrowStackOverflow); // Doesn't clobber LR.
m2l_->CallHelper(r_tgt, kQuickThrowStackOverflow, false /* MarkSafepointPC */,
false /* UseLink */);
}
private:
const size_t sp_displace_;
};
OpRegRegImm(kOpSub, new_sp, rs_rMIPS_SP, frame_sub);
LIR* branch = OpCmpBranch(kCondUlt, new_sp, check_reg, nullptr);
AddSlowPath(new(arena_)StackOverflowSlowPath(this, branch, spill_count * 4));
// TODO: avoid copy for small frame sizes.
OpRegCopy(rs_rMIPS_SP, new_sp); // Establish stack
} else {
OpRegImm(kOpSub, rs_rMIPS_SP, frame_sub);
}
FlushIns(ArgLocs, rl_method);
FreeTemp(rs_rMIPS_ARG0);
FreeTemp(rs_rMIPS_ARG1);
FreeTemp(rs_rMIPS_ARG2);
FreeTemp(rs_rMIPS_ARG3);
}
void MipsMir2Lir::GenExitSequence() {
/*
* In the exit path, rMIPS_RET0/rMIPS_RET1 are live - make sure they aren't
* allocated by the register utilities as temps.
*/
LockTemp(rs_rMIPS_RET0);
LockTemp(rs_rMIPS_RET1);
NewLIR0(kPseudoMethodExit);
UnSpillCoreRegs();
OpReg(kOpBx, rs_rRA);
}
void MipsMir2Lir::GenSpecialExitSequence() {
OpReg(kOpBx, rs_rRA);
}
} // namespace art