// Copyright 2012 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/assembler-inl.h"
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#include "src/deoptimizer.h"
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#include "src/objects-inl.h"
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#include "src/register-configuration.h"
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#include "src/safepoint-table.h"
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namespace v8 {
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namespace internal {
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const int Deoptimizer::table_entry_size_ = 8;
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#define __ masm()->
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// This code tries to be close to ia32 code so that any changes can be
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// easily ported.
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void Deoptimizer::TableEntryGenerator::Generate() {
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GeneratePrologue();
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// Save all general purpose registers before messing with them.
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const int kNumberOfRegisters = Register::kNumRegisters;
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// Everything but pc, lr and ip which will be saved but not restored.
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RegList restored_regs = kJSCallerSaved | kCalleeSaved | ip.bit();
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const int kDoubleRegsSize = kDoubleSize * DwVfpRegister::kNumRegisters;
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const int kFloatRegsSize = kFloatSize * SwVfpRegister::kNumRegisters;
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// Save all allocatable VFP registers before messing with them.
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{
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// We use a run-time check for VFP32DREGS.
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CpuFeatureScope scope(masm(), VFP32DREGS,
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CpuFeatureScope::kDontCheckSupported);
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UseScratchRegisterScope temps(masm());
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Register scratch = temps.Acquire();
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// Check CPU flags for number of registers, setting the Z condition flag.
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__ CheckFor32DRegs(scratch);
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// Push registers d0-d15, and possibly d16-d31, on the stack.
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// If d16-d31 are not pushed, decrease the stack pointer instead.
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__ vstm(db_w, sp, d16, d31, ne);
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__ sub(sp, sp, Operand(16 * kDoubleSize), LeaveCC, eq);
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__ vstm(db_w, sp, d0, d15);
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// Push registers s0-s31 on the stack.
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__ vstm(db_w, sp, s0, s31);
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}
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// Push all 16 registers (needed to populate FrameDescription::registers_).
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// TODO(1588) Note that using pc with stm is deprecated, so we should perhaps
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// handle this a bit differently.
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__ stm(db_w, sp, restored_regs | sp.bit() | lr.bit() | pc.bit());
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{
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UseScratchRegisterScope temps(masm());
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Register scratch = temps.Acquire();
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__ mov(scratch, Operand(ExternalReference::Create(
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IsolateAddressId::kCEntryFPAddress, isolate())));
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__ str(fp, MemOperand(scratch));
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}
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const int kSavedRegistersAreaSize =
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(kNumberOfRegisters * kPointerSize) + kDoubleRegsSize + kFloatRegsSize;
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// Get the bailout id from the stack.
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__ ldr(r2, MemOperand(sp, kSavedRegistersAreaSize));
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// Get the address of the location in the code object (r3) (return
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// address for lazy deoptimization) and compute the fp-to-sp delta in
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// register r4.
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__ mov(r3, lr);
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// Correct one word for bailout id.
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__ add(r4, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
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__ sub(r4, fp, r4);
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// Allocate a new deoptimizer object.
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// Pass four arguments in r0 to r3 and fifth argument on stack.
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__ PrepareCallCFunction(6);
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__ mov(r0, Operand(0));
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Label context_check;
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__ ldr(r1, MemOperand(fp, CommonFrameConstants::kContextOrFrameTypeOffset));
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__ JumpIfSmi(r1, &context_check);
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__ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
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__ bind(&context_check);
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__ mov(r1, Operand(static_cast<int>(deopt_kind())));
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// r2: bailout id already loaded.
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// r3: code address or 0 already loaded.
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__ str(r4, MemOperand(sp, 0 * kPointerSize)); // Fp-to-sp delta.
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__ mov(r5, Operand(ExternalReference::isolate_address(isolate())));
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__ str(r5, MemOperand(sp, 1 * kPointerSize)); // Isolate.
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// Call Deoptimizer::New().
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{
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AllowExternalCallThatCantCauseGC scope(masm());
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__ CallCFunction(ExternalReference::new_deoptimizer_function(), 6);
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}
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// Preserve "deoptimizer" object in register r0 and get the input
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// frame descriptor pointer to r1 (deoptimizer->input_);
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__ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
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// Copy core registers into FrameDescription::registers_[kNumRegisters].
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DCHECK_EQ(Register::kNumRegisters, kNumberOfRegisters);
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for (int i = 0; i < kNumberOfRegisters; i++) {
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int offset = (i * kPointerSize) + FrameDescription::registers_offset();
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__ ldr(r2, MemOperand(sp, i * kPointerSize));
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__ str(r2, MemOperand(r1, offset));
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}
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// Copy VFP registers to
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// double_registers_[DoubleRegister::kNumAllocatableRegisters]
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int double_regs_offset = FrameDescription::double_registers_offset();
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const RegisterConfiguration* config = RegisterConfiguration::Default();
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for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
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int code = config->GetAllocatableDoubleCode(i);
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int dst_offset = code * kDoubleSize + double_regs_offset;
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int src_offset =
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code * kDoubleSize + kNumberOfRegisters * kPointerSize + kFloatRegsSize;
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__ vldr(d0, sp, src_offset);
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__ vstr(d0, r1, dst_offset);
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}
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// Copy VFP registers to
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// float_registers_[FloatRegister::kNumAllocatableRegisters]
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int float_regs_offset = FrameDescription::float_registers_offset();
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for (int i = 0; i < config->num_allocatable_float_registers(); ++i) {
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int code = config->GetAllocatableFloatCode(i);
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int dst_offset = code * kFloatSize + float_regs_offset;
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int src_offset = code * kFloatSize + kNumberOfRegisters * kPointerSize;
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__ ldr(r2, MemOperand(sp, src_offset));
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__ str(r2, MemOperand(r1, dst_offset));
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}
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// Remove the bailout id and the saved registers from the stack.
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__ add(sp, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
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// Compute a pointer to the unwinding limit in register r2; that is
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// the first stack slot not part of the input frame.
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__ ldr(r2, MemOperand(r1, FrameDescription::frame_size_offset()));
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__ add(r2, r2, sp);
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// Unwind the stack down to - but not including - the unwinding
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// limit and copy the contents of the activation frame to the input
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// frame description.
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__ add(r3, r1, Operand(FrameDescription::frame_content_offset()));
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Label pop_loop;
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Label pop_loop_header;
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__ b(&pop_loop_header);
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__ bind(&pop_loop);
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__ pop(r4);
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__ str(r4, MemOperand(r3, 0));
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__ add(r3, r3, Operand(sizeof(uint32_t)));
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__ bind(&pop_loop_header);
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__ cmp(r2, sp);
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__ b(ne, &pop_loop);
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// Compute the output frame in the deoptimizer.
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__ push(r0); // Preserve deoptimizer object across call.
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// r0: deoptimizer object; r1: scratch.
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__ PrepareCallCFunction(1);
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// Call Deoptimizer::ComputeOutputFrames().
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{
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AllowExternalCallThatCantCauseGC scope(masm());
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__ CallCFunction(ExternalReference::compute_output_frames_function(), 1);
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}
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__ pop(r0); // Restore deoptimizer object (class Deoptimizer).
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__ ldr(sp, MemOperand(r0, Deoptimizer::caller_frame_top_offset()));
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// Replace the current (input) frame with the output frames.
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Label outer_push_loop, inner_push_loop,
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outer_loop_header, inner_loop_header;
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// Outer loop state: r4 = current "FrameDescription** output_",
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// r1 = one past the last FrameDescription**.
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__ ldr(r1, MemOperand(r0, Deoptimizer::output_count_offset()));
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__ ldr(r4, MemOperand(r0, Deoptimizer::output_offset())); // r4 is output_.
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__ add(r1, r4, Operand(r1, LSL, 2));
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__ jmp(&outer_loop_header);
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__ bind(&outer_push_loop);
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// Inner loop state: r2 = current FrameDescription*, r3 = loop index.
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__ ldr(r2, MemOperand(r4, 0)); // output_[ix]
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__ ldr(r3, MemOperand(r2, FrameDescription::frame_size_offset()));
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__ jmp(&inner_loop_header);
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__ bind(&inner_push_loop);
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__ sub(r3, r3, Operand(sizeof(uint32_t)));
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__ add(r6, r2, Operand(r3));
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__ ldr(r6, MemOperand(r6, FrameDescription::frame_content_offset()));
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__ push(r6);
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__ bind(&inner_loop_header);
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__ cmp(r3, Operand::Zero());
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__ b(ne, &inner_push_loop); // test for gt?
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__ add(r4, r4, Operand(kPointerSize));
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__ bind(&outer_loop_header);
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__ cmp(r4, r1);
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__ b(lt, &outer_push_loop);
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__ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
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for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
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int code = config->GetAllocatableDoubleCode(i);
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DwVfpRegister reg = DwVfpRegister::from_code(code);
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int src_offset = code * kDoubleSize + double_regs_offset;
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__ vldr(reg, r1, src_offset);
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}
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// Push pc and continuation from the last output frame.
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__ ldr(r6, MemOperand(r2, FrameDescription::pc_offset()));
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__ push(r6);
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__ ldr(r6, MemOperand(r2, FrameDescription::continuation_offset()));
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__ push(r6);
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// Push the registers from the last output frame.
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for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
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int offset = (i * kPointerSize) + FrameDescription::registers_offset();
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__ ldr(r6, MemOperand(r2, offset));
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__ push(r6);
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}
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// Restore the registers from the stack.
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__ ldm(ia_w, sp, restored_regs); // all but pc registers.
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__ InitializeRootRegister();
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// Remove sp, lr and pc.
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__ Drop(3);
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{
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UseScratchRegisterScope temps(masm());
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Register scratch = temps.Acquire();
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__ pop(scratch); // get continuation, leave pc on stack
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__ pop(lr);
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__ Jump(scratch);
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}
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__ stop("Unreachable.");
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}
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void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
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// Create a sequence of deoptimization entries.
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// Note that registers are still live when jumping to an entry.
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// We need to be able to generate immediates up to kMaxNumberOfEntries. On
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// ARMv7, we can use movw (with a maximum immediate of 0xFFFF). On ARMv6, we
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// need two instructions.
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STATIC_ASSERT((kMaxNumberOfEntries - 1) <= 0xFFFF);
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UseScratchRegisterScope temps(masm());
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Register scratch = temps.Acquire();
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if (CpuFeatures::IsSupported(ARMv7)) {
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CpuFeatureScope scope(masm(), ARMv7);
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Label done;
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for (int i = 0; i < count(); i++) {
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int start = masm()->pc_offset();
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USE(start);
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__ movw(scratch, i);
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__ b(&done);
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DCHECK_EQ(table_entry_size_, masm()->pc_offset() - start);
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}
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__ bind(&done);
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} else {
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// We want to keep table_entry_size_ == 8 (since this is the common case),
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// but we need two instructions to load most immediates over 0xFF. To handle
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// this, we set the low byte in the main table, and then set the high byte
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// in a separate table if necessary.
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Label high_fixes[256];
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int high_fix_max = (count() - 1) >> 8;
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DCHECK_GT(arraysize(high_fixes), static_cast<size_t>(high_fix_max));
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for (int i = 0; i < count(); i++) {
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int start = masm()->pc_offset();
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USE(start);
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__ mov(scratch, Operand(i & 0xFF)); // Set the low byte.
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__ b(&high_fixes[i >> 8]); // Jump to the secondary table.
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DCHECK_EQ(table_entry_size_, masm()->pc_offset() - start);
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}
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// Generate the secondary table, to set the high byte.
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for (int high = 1; high <= high_fix_max; high++) {
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__ bind(&high_fixes[high]);
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__ orr(scratch, scratch, Operand(high << 8));
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// If this isn't the last entry, emit a branch to the end of the table.
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// The last entry can just fall through.
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if (high < high_fix_max) __ b(&high_fixes[0]);
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}
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// Bind high_fixes[0] last, for indices like 0x00**. This case requires no
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// fix-up, so for (common) small tables we can jump here, then just fall
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// through with no additional branch.
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__ bind(&high_fixes[0]);
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}
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__ push(scratch);
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}
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bool Deoptimizer::PadTopOfStackRegister() { return false; }
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void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
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SetFrameSlot(offset, value);
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}
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void FrameDescription::SetCallerFp(unsigned offset, intptr_t value) {
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SetFrameSlot(offset, value);
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}
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void FrameDescription::SetCallerConstantPool(unsigned offset, intptr_t value) {
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// No embedded constant pool support.
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UNREACHABLE();
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}
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#undef __
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} // namespace internal
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} // namespace v8
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