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 
12 namespace v8 {
13 namespace internal {
14 
15 #define __ ACCESS_MASM(masm)
16 
17 
ProbeTable(Isolate * isolate,MacroAssembler * masm,Code::Flags flags,bool leave_frame,StubCache::Table table,Register receiver,Register name,Register offset,Register scratch,Register scratch2,Register offset_scratch)18 static 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 
GenerateProbe(MacroAssembler * masm,Code::Flags flags,bool leave_frame,Register receiver,Register name,Register scratch,Register extra,Register extra2,Register extra3)97 void 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