1// Copyright 2012 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/v8.h"
6
7#if V8_TARGET_ARCH_ARM
8
9#include "src/codegen.h"
10#include "src/ic/stub-cache.h"
11
12namespace v8 {
13namespace internal {
14
15#define __ ACCESS_MASM(masm)
16
17
18static void ProbeTable(Isolate* isolate, MacroAssembler* masm,
19                       Code::Flags flags, bool leave_frame,
20                       StubCache::Table table, Register receiver, Register name,
21                       // Number of the cache entry, not scaled.
22                       Register offset, Register scratch, Register scratch2,
23                       Register offset_scratch) {
24  ExternalReference key_offset(isolate->stub_cache()->key_reference(table));
25  ExternalReference value_offset(isolate->stub_cache()->value_reference(table));
26  ExternalReference map_offset(isolate->stub_cache()->map_reference(table));
27
28  uint32_t key_off_addr = reinterpret_cast<uint32_t>(key_offset.address());
29  uint32_t value_off_addr = reinterpret_cast<uint32_t>(value_offset.address());
30  uint32_t map_off_addr = reinterpret_cast<uint32_t>(map_offset.address());
31
32  // Check the relative positions of the address fields.
33  DCHECK(value_off_addr > key_off_addr);
34  DCHECK((value_off_addr - key_off_addr) % 4 == 0);
35  DCHECK((value_off_addr - key_off_addr) < (256 * 4));
36  DCHECK(map_off_addr > key_off_addr);
37  DCHECK((map_off_addr - key_off_addr) % 4 == 0);
38  DCHECK((map_off_addr - key_off_addr) < (256 * 4));
39
40  Label miss;
41  Register base_addr = scratch;
42  scratch = no_reg;
43
44  // Multiply by 3 because there are 3 fields per entry (name, code, map).
45  __ add(offset_scratch, offset, Operand(offset, LSL, 1));
46
47  // Calculate the base address of the entry.
48  __ mov(base_addr, Operand(key_offset));
49  __ add(base_addr, base_addr, Operand(offset_scratch, LSL, kPointerSizeLog2));
50
51  // Check that the key in the entry matches the name.
52  __ ldr(ip, MemOperand(base_addr, 0));
53  __ cmp(name, ip);
54  __ b(ne, &miss);
55
56  // Check the map matches.
57  __ ldr(ip, MemOperand(base_addr, map_off_addr - key_off_addr));
58  __ ldr(scratch2, FieldMemOperand(receiver, HeapObject::kMapOffset));
59  __ cmp(ip, scratch2);
60  __ b(ne, &miss);
61
62  // Get the code entry from the cache.
63  Register code = scratch2;
64  scratch2 = no_reg;
65  __ ldr(code, MemOperand(base_addr, value_off_addr - key_off_addr));
66
67  // Check that the flags match what we're looking for.
68  Register flags_reg = base_addr;
69  base_addr = no_reg;
70  __ ldr(flags_reg, FieldMemOperand(code, Code::kFlagsOffset));
71  // It's a nice optimization if this constant is encodable in the bic insn.
72
73  uint32_t mask = Code::kFlagsNotUsedInLookup;
74  DCHECK(__ ImmediateFitsAddrMode1Instruction(mask));
75  __ bic(flags_reg, flags_reg, Operand(mask));
76  __ cmp(flags_reg, Operand(flags));
77  __ b(ne, &miss);
78
79#ifdef DEBUG
80  if (FLAG_test_secondary_stub_cache && table == StubCache::kPrimary) {
81    __ jmp(&miss);
82  } else if (FLAG_test_primary_stub_cache && table == StubCache::kSecondary) {
83    __ jmp(&miss);
84  }
85#endif
86
87  if (leave_frame) __ LeaveFrame(StackFrame::INTERNAL);
88
89  // Jump to the first instruction in the code stub.
90  __ add(pc, code, Operand(Code::kHeaderSize - kHeapObjectTag));
91
92  // Miss: fall through.
93  __ bind(&miss);
94}
95
96
97void StubCache::GenerateProbe(MacroAssembler* masm, Code::Flags flags,
98                              bool leave_frame, Register receiver,
99                              Register name, Register scratch, Register extra,
100                              Register extra2, Register extra3) {
101  Isolate* isolate = masm->isolate();
102  Label miss;
103
104  // Make sure that code is valid. The multiplying code relies on the
105  // entry size being 12.
106  DCHECK(sizeof(Entry) == 12);
107
108  // Make sure the flags does not name a specific type.
109  DCHECK(Code::ExtractTypeFromFlags(flags) == 0);
110
111  // Make sure that there are no register conflicts.
112  DCHECK(!scratch.is(receiver));
113  DCHECK(!scratch.is(name));
114  DCHECK(!extra.is(receiver));
115  DCHECK(!extra.is(name));
116  DCHECK(!extra.is(scratch));
117  DCHECK(!extra2.is(receiver));
118  DCHECK(!extra2.is(name));
119  DCHECK(!extra2.is(scratch));
120  DCHECK(!extra2.is(extra));
121
122  // Check scratch, extra and extra2 registers are valid.
123  DCHECK(!scratch.is(no_reg));
124  DCHECK(!extra.is(no_reg));
125  DCHECK(!extra2.is(no_reg));
126  DCHECK(!extra3.is(no_reg));
127
128  Counters* counters = masm->isolate()->counters();
129  __ IncrementCounter(counters->megamorphic_stub_cache_probes(), 1, extra2,
130                      extra3);
131
132  // Check that the receiver isn't a smi.
133  __ JumpIfSmi(receiver, &miss);
134
135  // Get the map of the receiver and compute the hash.
136  __ ldr(scratch, FieldMemOperand(name, Name::kHashFieldOffset));
137  __ ldr(ip, FieldMemOperand(receiver, HeapObject::kMapOffset));
138  __ add(scratch, scratch, Operand(ip));
139  uint32_t mask = kPrimaryTableSize - 1;
140  // We shift out the last two bits because they are not part of the hash and
141  // they are always 01 for maps.
142  __ mov(scratch, Operand(scratch, LSR, kCacheIndexShift));
143  // Mask down the eor argument to the minimum to keep the immediate
144  // ARM-encodable.
145  __ eor(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask));
146  // Prefer and_ to ubfx here because ubfx takes 2 cycles.
147  __ and_(scratch, scratch, Operand(mask));
148
149  // Probe the primary table.
150  ProbeTable(isolate, masm, flags, leave_frame, kPrimary, receiver, name,
151             scratch, extra, extra2, extra3);
152
153  // Primary miss: Compute hash for secondary probe.
154  __ sub(scratch, scratch, Operand(name, LSR, kCacheIndexShift));
155  uint32_t mask2 = kSecondaryTableSize - 1;
156  __ add(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask2));
157  __ and_(scratch, scratch, Operand(mask2));
158
159  // Probe the secondary table.
160  ProbeTable(isolate, masm, flags, leave_frame, kSecondary, receiver, name,
161             scratch, extra, extra2, extra3);
162
163  // Cache miss: Fall-through and let caller handle the miss by
164  // entering the runtime system.
165  __ bind(&miss);
166  __ IncrementCounter(counters->megamorphic_stub_cache_misses(), 1, extra2,
167                      extra3);
168}
169
170
171#undef __
172}
173}  // namespace v8::internal
174
175#endif  // V8_TARGET_ARCH_ARM
176