compiler/dex/quick/mips/call_mips.cc - platform/art - Git at Google

 /*
  * 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 "art_method.h"
 #include "base/logging.h"
 #include "dex/mir_graph.h"
 #include "dex/quick/dex_file_to_method_inliner_map.h"
 #include "dex/quick/mir_to_lir-inl.h"
 #include "driver/compiler_driver.h"
 #include "driver/compiler_options.h"
 #include "entrypoints/quick/quick_entrypoints.h"
 #include "gc/accounting/card_table.h"
 #include "mips_lir.h"
 #include "mirror/object_array-inl.h"

 namespace art {

 bool MipsMir2Lir::GenSpecialCase(BasicBlock* bb, MIR* mir, const InlineMethod& special) {
   // TODO
   UNUSED(bb, mir, special);
   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
  *   jalr  rZERO, rRA
  * done:
  *
  */
 void MipsMir2Lir::GenLargeSparseSwitch(MIR* mir, DexOffset table_offset, RegLocation rl_src) {
   const uint16_t* table = mir_graph_->GetTable(mir, table_offset);
   // Add the table to the list - we'll process it later.
   SwitchTable* tab_rec =
       static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
   tab_rec->switch_mir = mir;
   tab_rec->table = table;
   tab_rec->vaddr = current_dalvik_offset_;
   int elements = table[1];
   switch_tables_.push_back(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 = AllocPtrSizeTemp();
   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 = AllocPtrSizeTemp();
   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, nullptr);
   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);
   const RegStorage rs_ra = TargetPtrReg(kLr);
   OpRegRegReg(kOpAdd, rs_ra, rs_ra, r_disp);
   OpReg(kOpBx, rs_ra);
   // 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
  *   jalr  rZERO, rRA
  * done:
  */
 void MipsMir2Lir::GenLargePackedSwitch(MIR* mir, DexOffset table_offset, RegLocation rl_src) {
   const uint16_t* table = mir_graph_->GetTable(mir, table_offset);
   // Add the table to the list - we'll process it later.
   SwitchTable* tab_rec =
       static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
   tab_rec->switch_mir = mir;
   tab_rec->table = table;
   tab_rec->vaddr = current_dalvik_offset_;
   int size = table[1];
   switch_tables_.push_back(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, nullptr);

   // Materialize the table base pointer.
   RegStorage r_base = AllocPtrSizeTemp();
   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 rRA and go.
   const RegStorage rs_ra = TargetPtrReg(kLr);
   OpRegRegReg(kOpAdd, rs_ra, rs_ra, r_disp);
   OpReg(kOpBx, rs_ra);

   // Branch_over target here.
   LIR* target = NewLIR0(kPseudoTargetLabel);
   branch_over->target = target;
 }

 void MipsMir2Lir::GenMoveException(RegLocation rl_dest) {
   int ex_offset = cu_->target64 ? Thread::ExceptionOffset<8>().Int32Value() :
       Thread::ExceptionOffset<4>().Int32Value();
   RegLocation rl_result = EvalLoc(rl_dest, kRefReg, true);
   RegStorage reset_reg = AllocTempRef();
   LoadRefDisp(TargetPtrReg(kSelf), ex_offset, rl_result.reg, kNotVolatile);
   LoadConstant(reset_reg, 0);
   StoreRefDisp(TargetPtrReg(kSelf), ex_offset, reset_reg, kNotVolatile);
   FreeTemp(reset_reg);
   StoreValue(rl_dest, rl_result);
 }

 void MipsMir2Lir::UnconditionallyMarkGCCard(RegStorage tgt_addr_reg) {
   RegStorage reg_card_base = AllocPtrSizeTemp();
   RegStorage reg_card_no = AllocPtrSizeTemp();
   if (cu_->target64) {
     // NOTE: native pointer.
     LoadWordDisp(TargetPtrReg(kSelf), Thread::CardTableOffset<8>().Int32Value(), reg_card_base);
     OpRegRegImm(kOpLsr, reg_card_no, tgt_addr_reg, gc::accounting::CardTable::kCardShift);
     StoreBaseIndexed(reg_card_base, reg_card_no, As32BitReg(reg_card_base), 0, kUnsignedByte);
   } else {
     // NOTE: native pointer.
     LoadWordDisp(TargetPtrReg(kSelf), 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);
   }
   FreeTemp(reg_card_base);
   FreeTemp(reg_card_no);
 }

 static dwarf::Reg DwarfCoreReg(int num) {
   return dwarf::Reg::MipsCore(num);
 }

 void MipsMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method) {
   DCHECK_EQ(cfi_.GetCurrentCFAOffset(), 0);
   int spill_count = num_core_spills_ + num_fp_spills_;
   /*
    * On entry, A0, A1, A2 & A3 are live. On Mips64, A4, A5, A6 & A7 are also live.
    * Let the register allocation mechanism know so it doesn't try to use any of them when
    * expanding the frame or flushing.
    */
   const RegStorage arg0 = TargetReg(kArg0);
   const RegStorage arg1 = TargetReg(kArg1);
   const RegStorage arg2 = TargetReg(kArg2);
   const RegStorage arg3 = TargetReg(kArg3);
   const RegStorage arg4 = TargetReg(kArg4);
   const RegStorage arg5 = TargetReg(kArg5);
   const RegStorage arg6 = TargetReg(kArg6);
   const RegStorage arg7 = TargetReg(kArg7);

   LockTemp(arg0);
   LockTemp(arg1);
   LockTemp(arg2);
   LockTemp(arg3);
   if (cu_->target64) {
     LockTemp(arg4);
     LockTemp(arg5);
     LockTemp(arg6);
     LockTemp(arg7);
   }

   bool skip_overflow_check;
   InstructionSet target = (cu_->target64) ? kMips64 : kMips;
   int ptr_size = cu_->target64 ? 8 : 4;

   /*
    * We can safely skip the stack overflow check if we're
    * a leaf *and* our frame size < fudge factor.
    */

   skip_overflow_check = mir_graph_->MethodIsLeaf() && !FrameNeedsStackCheck(frame_size_, target);
   RegStorage check_reg = AllocPtrSizeTemp();
   RegStorage new_sp = AllocPtrSizeTemp();
   const RegStorage rs_sp = TargetPtrReg(kSp);
   const size_t kStackOverflowReservedUsableBytes = GetStackOverflowReservedBytes(target);
   const bool large_frame = static_cast<size_t>(frame_size_) > kStackOverflowReservedUsableBytes;
   bool generate_explicit_stack_overflow_check = large_frame ||
     !cu_->compiler_driver->GetCompilerOptions().GetImplicitStackOverflowChecks();

   if (!skip_overflow_check) {
     if (generate_explicit_stack_overflow_check) {
       // Load stack limit.
       if (cu_->target64) {
         LoadWordDisp(TargetPtrReg(kSelf), Thread::StackEndOffset<8>().Int32Value(), check_reg);
       } else {
         Load32Disp(TargetPtrReg(kSelf), Thread::StackEndOffset<4>().Int32Value(), check_reg);
       }
     } else {
       // Implicit stack overflow check.
       // Generate a load from [sp, #-overflowsize].  If this is in the stack
       // redzone we will get a segmentation fault.
       Load32Disp(rs_sp, -kStackOverflowReservedUsableBytes, rs_rZERO);
       MarkPossibleStackOverflowException();
     }
   }
   // 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 * ptr_size;
   if (!skip_overflow_check && generate_explicit_stack_overflow_check) {
     class StackOverflowSlowPath : public LIRSlowPath {
      public:
       StackOverflowSlowPath(Mir2Lir* m2l, LIR* branch, size_t sp_displace)
           : LIRSlowPath(m2l, branch), sp_displace_(sp_displace) {
       }
       void Compile() OVERRIDE {
         m2l_->ResetRegPool();
         m2l_->ResetDefTracking();
         GenerateTargetLabel(kPseudoThrowTarget);
         // RA is offset 0 since we push in reverse order.
         m2l_->LoadWordDisp(m2l_->TargetPtrReg(kSp), 0, m2l_->TargetPtrReg(kLr));
         m2l_->OpRegImm(kOpAdd, m2l_->TargetPtrReg(kSp), sp_displace_);
         m2l_->cfi().AdjustCFAOffset(-sp_displace_);
         m2l_->ClobberCallerSave();
         RegStorage r_tgt = m2l_->CallHelperSetup(kQuickThrowStackOverflow);  // Doesn't clobber LR.
         m2l_->CallHelper(r_tgt, kQuickThrowStackOverflow, false /* MarkSafepointPC */,
                          false /* UseLink */);
         m2l_->cfi().AdjustCFAOffset(sp_displace_);
       }

      private:
       const size_t sp_displace_;
     };
     OpRegRegImm(kOpSub, new_sp, rs_sp, frame_sub);
     LIR* branch = OpCmpBranch(kCondUlt, new_sp, check_reg, nullptr);
     AddSlowPath(new(arena_)StackOverflowSlowPath(this, branch, spill_count * ptr_size));
     // TODO: avoid copy for small frame sizes.
     OpRegCopy(rs_sp, new_sp);  // Establish stack.
     cfi_.AdjustCFAOffset(frame_sub);
   } else {
     // Here if skip_overflow_check or doing implicit stack overflow check.
     // Just make room on the stack for the frame now.
     OpRegImm(kOpSub, rs_sp, frame_sub);
     cfi_.AdjustCFAOffset(frame_sub);
   }

   FlushIns(ArgLocs, rl_method);

   FreeTemp(arg0);
   FreeTemp(arg1);
   FreeTemp(arg2);
   FreeTemp(arg3);
   if (cu_->target64) {
     FreeTemp(arg4);
     FreeTemp(arg5);
     FreeTemp(arg6);
     FreeTemp(arg7);
   }
 }

 void MipsMir2Lir::GenExitSequence() {
   cfi_.RememberState();
   /*
    * In the exit path, rMIPS_RET0/rMIPS_RET1 are live - make sure they aren't
    * allocated by the register utilities as temps.
    */
   LockTemp(TargetPtrReg(kRet0));
   LockTemp(TargetPtrReg(kRet1));

   UnSpillCoreRegs();
   OpReg(kOpBx, TargetPtrReg(kLr));
   // The CFI should be restored for any code that follows the exit block.
   cfi_.RestoreState();
   cfi_.DefCFAOffset(frame_size_);
 }

 void MipsMir2Lir::GenSpecialExitSequence() {
   OpReg(kOpBx, TargetPtrReg(kLr));
 }

 void MipsMir2Lir::GenSpecialEntryForSuspend() {
   // Keep 16-byte stack alignment - push A0, i.e. ArtMethod*, 2 filler words and RA for mips32,
   // but A0 and RA for mips64.
   core_spill_mask_ = (1u << TargetPtrReg(kLr).GetRegNum());
   num_core_spills_ = 1u;
   fp_spill_mask_ = 0u;
   num_fp_spills_ = 0u;
   frame_size_ = 16u;
   core_vmap_table_.clear();
   fp_vmap_table_.clear();
   const RegStorage rs_sp = TargetPtrReg(kSp);
   OpRegImm(kOpSub, rs_sp, frame_size_);
   cfi_.AdjustCFAOffset(frame_size_);
   StoreWordDisp(rs_sp, frame_size_ - (cu_->target64 ? 8 : 4), TargetPtrReg(kLr));
   cfi_.RelOffset(DwarfCoreReg(rRA), frame_size_ - (cu_->target64 ? 8 : 4));
   StoreWordDisp(rs_sp, 0, TargetPtrReg(kArg0));
   // Do not generate CFI for scratch register A0.
 }

 void MipsMir2Lir::GenSpecialExitForSuspend() {
   // Pop the frame. Don't pop ArtMethod*, it's no longer needed.
   const RegStorage rs_sp = TargetPtrReg(kSp);
   LoadWordDisp(rs_sp, frame_size_ - (cu_->target64 ? 8 : 4), TargetPtrReg(kLr));
   cfi_.Restore(DwarfCoreReg(rRA));
   OpRegImm(kOpAdd, rs_sp, frame_size_);
   cfi_.AdjustCFAOffset(-frame_size_);
 }

 /*
  * Bit of a hack here - in the absence of a real scheduling pass,
  * emit the next instruction in static & direct invoke sequences.
  */
 static int NextSDCallInsn(CompilationUnit* cu, CallInfo* info, int state,
                           const MethodReference& target_method, uint32_t, uintptr_t direct_code,
                           uintptr_t direct_method, InvokeType type) {
   Mir2Lir* cg = static_cast<Mir2Lir*>(cu->cg.get());
   if (info->string_init_offset != 0) {
     RegStorage arg0_ref = cg->TargetReg(kArg0, kRef);
     switch (state) {
     case 0: {  // Grab target method* from thread pointer
       cg->LoadWordDisp(cg->TargetPtrReg(kSelf), info->string_init_offset, arg0_ref);
       break;
     }
     case 1:  // Grab the code from the method*
       if (direct_code == 0) {
         int32_t offset = ArtMethod::EntryPointFromQuickCompiledCodeOffset(
             InstructionSetPointerSize(cu->instruction_set)).Int32Value();
         cg->LoadWordDisp(arg0_ref, offset, cg->TargetPtrReg(kInvokeTgt));
       }
       break;
     default:
       return -1;
     }
   } else if (direct_code != 0 && direct_method != 0) {
     switch (state) {
       case 0:  // Get the current Method* [sets kArg0]
         if (direct_code != static_cast<uintptr_t>(-1)) {
           if (cu->target64) {
             cg->LoadConstantWide(cg->TargetPtrReg(kInvokeTgt), direct_code);
           } else {
             cg->LoadConstant(cg->TargetPtrReg(kInvokeTgt), direct_code);
           }
         } else {
           cg->LoadCodeAddress(target_method, type, kInvokeTgt);
         }
         if (direct_method != static_cast<uintptr_t>(-1)) {
           if (cu->target64) {
             cg->LoadConstantWide(cg->TargetReg(kArg0, kRef), direct_method);
           } else {
             cg->LoadConstant(cg->TargetReg(kArg0, kRef), direct_method);
           }
         } else {
           cg->LoadMethodAddress(target_method, type, kArg0);
         }
         break;
       default:
         return -1;
     }
   } else {
     RegStorage arg0_ref = cg->TargetReg(kArg0, kRef);
     switch (state) {
       case 0:  // Get the current Method* [sets kArg0]
         // TUNING: we can save a reg copy if Method* has been promoted.
         cg->LoadCurrMethodDirect(arg0_ref);
         break;
       case 1:  // Get method->dex_cache_resolved_methods_
         cg->LoadRefDisp(arg0_ref,
                         ArtMethod::DexCacheResolvedMethodsOffset().Int32Value(),
                         arg0_ref,
                         kNotVolatile);
         // Set up direct code if known.
         if (direct_code != 0) {
           if (direct_code != static_cast<uintptr_t>(-1)) {
             if (cu->target64) {
               cg->LoadConstantWide(cg->TargetPtrReg(kInvokeTgt), direct_code);
             } else {
               cg->LoadConstant(cg->TargetPtrReg(kInvokeTgt), direct_code);
             }
           } else {
             CHECK_LT(target_method.dex_method_index, target_method.dex_file->NumMethodIds());
             cg->LoadCodeAddress(target_method, type, kInvokeTgt);
           }
         }
         break;
       case 2: {
         // Grab target method*
         CHECK_EQ(cu->dex_file, target_method.dex_file);
         const size_t pointer_size = GetInstructionSetPointerSize(cu->instruction_set);
         cg->LoadWordDisp(arg0_ref,
                          mirror::Array::DataOffset(pointer_size).Uint32Value() +
                          target_method.dex_method_index * pointer_size, arg0_ref);
         break;
       }
       case 3:  // Grab the code from the method*
         if (direct_code == 0) {
           int32_t offset = ArtMethod::EntryPointFromQuickCompiledCodeOffset(
               InstructionSetPointerSize(cu->instruction_set)).Int32Value();
           // Get the compiled code address [use *alt_from or kArg0, set kInvokeTgt]
           cg->LoadWordDisp(arg0_ref, offset, cg->TargetPtrReg(kInvokeTgt));
         }
         break;
       default:
         return -1;
     }
   }
   return state + 1;
 }

 NextCallInsn MipsMir2Lir::GetNextSDCallInsn() {
   return NextSDCallInsn;
 }

 LIR* MipsMir2Lir::GenCallInsn(const MirMethodLoweringInfo& method_info ATTRIBUTE_UNUSED) {
   return OpReg(kOpBlx, TargetPtrReg(kInvokeTgt));
 }

 }  // namespace art
	/*
	* 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 "art_method.h"
	#include "base/logging.h"
	#include "dex/mir_graph.h"
	#include "dex/quick/dex_file_to_method_inliner_map.h"
	#include "dex/quick/mir_to_lir-inl.h"
	#include "driver/compiler_driver.h"
	#include "driver/compiler_options.h"
	#include "entrypoints/quick/quick_entrypoints.h"
	#include "gc/accounting/card_table.h"
	#include "mips_lir.h"
	#include "mirror/object_array-inl.h"

	namespace art {

	bool MipsMir2Lir::GenSpecialCase(BasicBlock* bb, MIR* mir, const InlineMethod& special) {
	// TODO
	UNUSED(bb, mir, special);
	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
	* jalr rZERO, rRA
	* done:
	*
	*/
	void MipsMir2Lir::GenLargeSparseSwitch(MIR* mir, DexOffset table_offset, RegLocation rl_src) {
	const uint16_t* table = mir_graph_->GetTable(mir, table_offset);
	// Add the table to the list - we'll process it later.
	SwitchTable* tab_rec =
	static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
	tab_rec->switch_mir = mir;
	tab_rec->table = table;
	tab_rec->vaddr = current_dalvik_offset_;
	int elements = table[1];
	switch_tables_.push_back(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 = AllocPtrSizeTemp();
	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 = AllocPtrSizeTemp();
	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, nullptr);
	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);
	const RegStorage rs_ra = TargetPtrReg(kLr);
	OpRegRegReg(kOpAdd, rs_ra, rs_ra, r_disp);
	OpReg(kOpBx, rs_ra);
	// 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
	* jalr rZERO, rRA
	* done:
	*/
	void MipsMir2Lir::GenLargePackedSwitch(MIR* mir, DexOffset table_offset, RegLocation rl_src) {
	const uint16_t* table = mir_graph_->GetTable(mir, table_offset);
	// Add the table to the list - we'll process it later.
	SwitchTable* tab_rec =
	static_cast<SwitchTable*>(arena_->Alloc(sizeof(SwitchTable), kArenaAllocData));
	tab_rec->switch_mir = mir;
	tab_rec->table = table;
	tab_rec->vaddr = current_dalvik_offset_;
	int size = table[1];
	switch_tables_.push_back(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, nullptr);

	// Materialize the table base pointer.
	RegStorage r_base = AllocPtrSizeTemp();
	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 rRA and go.
	const RegStorage rs_ra = TargetPtrReg(kLr);
	OpRegRegReg(kOpAdd, rs_ra, rs_ra, r_disp);
	OpReg(kOpBx, rs_ra);

	// Branch_over target here.
	LIR* target = NewLIR0(kPseudoTargetLabel);
	branch_over->target = target;
	}

	void MipsMir2Lir::GenMoveException(RegLocation rl_dest) {
	int ex_offset = cu_->target64 ? Thread::ExceptionOffset<8>().Int32Value() :
	Thread::ExceptionOffset<4>().Int32Value();
	RegLocation rl_result = EvalLoc(rl_dest, kRefReg, true);
	RegStorage reset_reg = AllocTempRef();
	LoadRefDisp(TargetPtrReg(kSelf), ex_offset, rl_result.reg, kNotVolatile);
	LoadConstant(reset_reg, 0);
	StoreRefDisp(TargetPtrReg(kSelf), ex_offset, reset_reg, kNotVolatile);
	FreeTemp(reset_reg);
	StoreValue(rl_dest, rl_result);
	}

	void MipsMir2Lir::UnconditionallyMarkGCCard(RegStorage tgt_addr_reg) {
	RegStorage reg_card_base = AllocPtrSizeTemp();
	RegStorage reg_card_no = AllocPtrSizeTemp();
	if (cu_->target64) {
	// NOTE: native pointer.
	LoadWordDisp(TargetPtrReg(kSelf), Thread::CardTableOffset<8>().Int32Value(), reg_card_base);
	OpRegRegImm(kOpLsr, reg_card_no, tgt_addr_reg, gc::accounting::CardTable::kCardShift);
	StoreBaseIndexed(reg_card_base, reg_card_no, As32BitReg(reg_card_base), 0, kUnsignedByte);
	} else {
	// NOTE: native pointer.
	LoadWordDisp(TargetPtrReg(kSelf), 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);
	}
	FreeTemp(reg_card_base);
	FreeTemp(reg_card_no);
	}

	static dwarf::Reg DwarfCoreReg(int num) {
	return dwarf::Reg::MipsCore(num);
	}

	void MipsMir2Lir::GenEntrySequence(RegLocation* ArgLocs, RegLocation rl_method) {
	DCHECK_EQ(cfi_.GetCurrentCFAOffset(), 0);
	int spill_count = num_core_spills_ + num_fp_spills_;
	/*
	* On entry, A0, A1, A2 & A3 are live. On Mips64, A4, A5, A6 & A7 are also live.
	* Let the register allocation mechanism know so it doesn't try to use any of them when
	* expanding the frame or flushing.
	*/
	const RegStorage arg0 = TargetReg(kArg0);
	const RegStorage arg1 = TargetReg(kArg1);
	const RegStorage arg2 = TargetReg(kArg2);
	const RegStorage arg3 = TargetReg(kArg3);
	const RegStorage arg4 = TargetReg(kArg4);
	const RegStorage arg5 = TargetReg(kArg5);
	const RegStorage arg6 = TargetReg(kArg6);
	const RegStorage arg7 = TargetReg(kArg7);

	LockTemp(arg0);
	LockTemp(arg1);
	LockTemp(arg2);
	LockTemp(arg3);
	if (cu_->target64) {
	LockTemp(arg4);
	LockTemp(arg5);
	LockTemp(arg6);
	LockTemp(arg7);
	}

	bool skip_overflow_check;
	InstructionSet target = (cu_->target64) ? kMips64 : kMips;
	int ptr_size = cu_->target64 ? 8 : 4;

	/*
	* We can safely skip the stack overflow check if we're
	* a leaf and our frame size < fudge factor.
	*/

	skip_overflow_check = mir_graph_->MethodIsLeaf() && !FrameNeedsStackCheck(frame_size_, target);
	RegStorage check_reg = AllocPtrSizeTemp();
	RegStorage new_sp = AllocPtrSizeTemp();
	const RegStorage rs_sp = TargetPtrReg(kSp);
	const size_t kStackOverflowReservedUsableBytes = GetStackOverflowReservedBytes(target);
	const bool large_frame = static_cast<size_t>(frame_size_) > kStackOverflowReservedUsableBytes;
	bool generate_explicit_stack_overflow_check = large_frame \|\|
	!cu_->compiler_driver->GetCompilerOptions().GetImplicitStackOverflowChecks();

	if (!skip_overflow_check) {
	if (generate_explicit_stack_overflow_check) {
	// Load stack limit.
	if (cu_->target64) {
	LoadWordDisp(TargetPtrReg(kSelf), Thread::StackEndOffset<8>().Int32Value(), check_reg);
	} else {
	Load32Disp(TargetPtrReg(kSelf), Thread::StackEndOffset<4>().Int32Value(), check_reg);
	}
	} else {
	// Implicit stack overflow check.
	// Generate a load from [sp, #-overflowsize]. If this is in the stack
	// redzone we will get a segmentation fault.
	Load32Disp(rs_sp, -kStackOverflowReservedUsableBytes, rs_rZERO);
	MarkPossibleStackOverflowException();
	}
	}
	// 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 * ptr_size;
	if (!skip_overflow_check && generate_explicit_stack_overflow_check) {
	class StackOverflowSlowPath : public LIRSlowPath {
	public:
	StackOverflowSlowPath(Mir2Lir* m2l, LIR* branch, size_t sp_displace)
	: LIRSlowPath(m2l, branch), sp_displace_(sp_displace) {
	}
	void Compile() OVERRIDE {
	m2l_->ResetRegPool();
	m2l_->ResetDefTracking();
	GenerateTargetLabel(kPseudoThrowTarget);
	// RA is offset 0 since we push in reverse order.
	m2l_->LoadWordDisp(m2l_->TargetPtrReg(kSp), 0, m2l_->TargetPtrReg(kLr));
	m2l_->OpRegImm(kOpAdd, m2l_->TargetPtrReg(kSp), sp_displace_);
	m2l_->cfi().AdjustCFAOffset(-sp_displace_);
	m2l_->ClobberCallerSave();
	RegStorage r_tgt = m2l_->CallHelperSetup(kQuickThrowStackOverflow); // Doesn't clobber LR.
	m2l_->CallHelper(r_tgt, kQuickThrowStackOverflow, false /* MarkSafepointPC */,
	false /* UseLink */);
	m2l_->cfi().AdjustCFAOffset(sp_displace_);
	}

	private:
	const size_t sp_displace_;
	};
	OpRegRegImm(kOpSub, new_sp, rs_sp, frame_sub);
	LIR* branch = OpCmpBranch(kCondUlt, new_sp, check_reg, nullptr);
	AddSlowPath(new(arena_)StackOverflowSlowPath(this, branch, spill_count * ptr_size));
	// TODO: avoid copy for small frame sizes.
	OpRegCopy(rs_sp, new_sp); // Establish stack.
	cfi_.AdjustCFAOffset(frame_sub);
	} else {
	// Here if skip_overflow_check or doing implicit stack overflow check.
	// Just make room on the stack for the frame now.
	OpRegImm(kOpSub, rs_sp, frame_sub);
	cfi_.AdjustCFAOffset(frame_sub);
	}

	FlushIns(ArgLocs, rl_method);

	FreeTemp(arg0);
	FreeTemp(arg1);
	FreeTemp(arg2);
	FreeTemp(arg3);
	if (cu_->target64) {
	FreeTemp(arg4);
	FreeTemp(arg5);
	FreeTemp(arg6);
	FreeTemp(arg7);
	}
	}

	void MipsMir2Lir::GenExitSequence() {
	cfi_.RememberState();
	/*
	* In the exit path, rMIPS_RET0/rMIPS_RET1 are live - make sure they aren't
	* allocated by the register utilities as temps.
	*/
	LockTemp(TargetPtrReg(kRet0));
	LockTemp(TargetPtrReg(kRet1));

	UnSpillCoreRegs();
	OpReg(kOpBx, TargetPtrReg(kLr));
	// The CFI should be restored for any code that follows the exit block.
	cfi_.RestoreState();
	cfi_.DefCFAOffset(frame_size_);
	}

	void MipsMir2Lir::GenSpecialExitSequence() {
	OpReg(kOpBx, TargetPtrReg(kLr));
	}

	void MipsMir2Lir::GenSpecialEntryForSuspend() {
	// Keep 16-byte stack alignment - push A0, i.e. ArtMethod*, 2 filler words and RA for mips32,
	// but A0 and RA for mips64.
	core_spill_mask_ = (1u << TargetPtrReg(kLr).GetRegNum());
	num_core_spills_ = 1u;
	fp_spill_mask_ = 0u;
	num_fp_spills_ = 0u;
	frame_size_ = 16u;
	core_vmap_table_.clear();
	fp_vmap_table_.clear();
	const RegStorage rs_sp = TargetPtrReg(kSp);
	OpRegImm(kOpSub, rs_sp, frame_size_);
	cfi_.AdjustCFAOffset(frame_size_);
	StoreWordDisp(rs_sp, frame_size_ - (cu_->target64 ? 8 : 4), TargetPtrReg(kLr));
	cfi_.RelOffset(DwarfCoreReg(rRA), frame_size_ - (cu_->target64 ? 8 : 4));
	StoreWordDisp(rs_sp, 0, TargetPtrReg(kArg0));
	// Do not generate CFI for scratch register A0.
	}

	void MipsMir2Lir::GenSpecialExitForSuspend() {
	// Pop the frame. Don't pop ArtMethod*, it's no longer needed.
	const RegStorage rs_sp = TargetPtrReg(kSp);
	LoadWordDisp(rs_sp, frame_size_ - (cu_->target64 ? 8 : 4), TargetPtrReg(kLr));
	cfi_.Restore(DwarfCoreReg(rRA));
	OpRegImm(kOpAdd, rs_sp, frame_size_);
	cfi_.AdjustCFAOffset(-frame_size_);
	}

	/*
	* Bit of a hack here - in the absence of a real scheduling pass,
	* emit the next instruction in static & direct invoke sequences.
	*/
	static int NextSDCallInsn(CompilationUnit* cu, CallInfo* info, int state,
	const MethodReference& target_method, uint32_t, uintptr_t direct_code,
	uintptr_t direct_method, InvokeType type) {
	Mir2Lir* cg = static_cast<Mir2Lir*>(cu->cg.get());
	if (info->string_init_offset != 0) {
	RegStorage arg0_ref = cg->TargetReg(kArg0, kRef);
	switch (state) {
	case 0: { // Grab target method* from thread pointer
	cg->LoadWordDisp(cg->TargetPtrReg(kSelf), info->string_init_offset, arg0_ref);
	break;
	}
	case 1: // Grab the code from the method*
	if (direct_code == 0) {
	int32_t offset = ArtMethod::EntryPointFromQuickCompiledCodeOffset(
	InstructionSetPointerSize(cu->instruction_set)).Int32Value();
	cg->LoadWordDisp(arg0_ref, offset, cg->TargetPtrReg(kInvokeTgt));
	}
	break;
	default:
	return -1;
	}
	} else if (direct_code != 0 && direct_method != 0) {
	switch (state) {
	case 0: // Get the current Method* [sets kArg0]
	if (direct_code != static_cast<uintptr_t>(-1)) {
	if (cu->target64) {
	cg->LoadConstantWide(cg->TargetPtrReg(kInvokeTgt), direct_code);
	} else {
	cg->LoadConstant(cg->TargetPtrReg(kInvokeTgt), direct_code);
	}
	} else {
	cg->LoadCodeAddress(target_method, type, kInvokeTgt);
	}
	if (direct_method != static_cast<uintptr_t>(-1)) {
	if (cu->target64) {
	cg->LoadConstantWide(cg->TargetReg(kArg0, kRef), direct_method);
	} else {
	cg->LoadConstant(cg->TargetReg(kArg0, kRef), direct_method);
	}
	} else {
	cg->LoadMethodAddress(target_method, type, kArg0);
	}
	break;
	default:
	return -1;
	}
	} else {
	RegStorage arg0_ref = cg->TargetReg(kArg0, kRef);
	switch (state) {
	case 0: // Get the current Method* [sets kArg0]
	// TUNING: we can save a reg copy if Method* has been promoted.
	cg->LoadCurrMethodDirect(arg0_ref);
	break;
	case 1: // Get method->dex_cache_resolved_methods_
	cg->LoadRefDisp(arg0_ref,
	ArtMethod::DexCacheResolvedMethodsOffset().Int32Value(),
	arg0_ref,
	kNotVolatile);
	// Set up direct code if known.
	if (direct_code != 0) {
	if (direct_code != static_cast<uintptr_t>(-1)) {
	if (cu->target64) {
	cg->LoadConstantWide(cg->TargetPtrReg(kInvokeTgt), direct_code);
	} else {
	cg->LoadConstant(cg->TargetPtrReg(kInvokeTgt), direct_code);
	}
	} else {
	CHECK_LT(target_method.dex_method_index, target_method.dex_file->NumMethodIds());
	cg->LoadCodeAddress(target_method, type, kInvokeTgt);
	}
	}
	break;
	case 2: {
	// Grab target method*
	CHECK_EQ(cu->dex_file, target_method.dex_file);
	const size_t pointer_size = GetInstructionSetPointerSize(cu->instruction_set);
	cg->LoadWordDisp(arg0_ref,
	mirror::Array::DataOffset(pointer_size).Uint32Value() +
	target_method.dex_method_index * pointer_size, arg0_ref);
	break;
	}
	case 3: // Grab the code from the method*
	if (direct_code == 0) {
	int32_t offset = ArtMethod::EntryPointFromQuickCompiledCodeOffset(
	InstructionSetPointerSize(cu->instruction_set)).Int32Value();
	// Get the compiled code address [use *alt_from or kArg0, set kInvokeTgt]
	cg->LoadWordDisp(arg0_ref, offset, cg->TargetPtrReg(kInvokeTgt));
	}
	break;
	default:
	return -1;
	}
	}
	return state + 1;
	}

	NextCallInsn MipsMir2Lir::GetNextSDCallInsn() {
	return NextSDCallInsn;
	}

	LIR* MipsMir2Lir::GenCallInsn(const MirMethodLoweringInfo& method_info ATTRIBUTE_UNUSED) {
	return OpReg(kOpBlx, TargetPtrReg(kInvokeTgt));
	}

	} // namespace art