Reviewers: Hannes Payer,
Description:
Unravel kHeapObjectTagSize from the stub cache.
BUG=
Please review this at https://codereview.chromium.org/401613003/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+39, -38 lines):
M src/arm/stub-cache-arm.cc
M src/arm64/stub-cache-arm64.cc
M src/ia32/stub-cache-ia32.cc
M src/mips/stub-cache-mips.cc
M src/mips64/stub-cache-mips64.cc
M src/stub-cache.h
M src/x64/stub-cache-x64.cc
M src/x87/stub-cache-x87.cc
Index: src/arm/stub-cache-arm.cc
diff --git a/src/arm/stub-cache-arm.cc b/src/arm/stub-cache-arm.cc
index
1898dbc6fb2704c9fee39495c8eff4fde57d90c8..50c3ff12d9db508e460c22a36c733d5bbced90db
100644
--- a/src/arm/stub-cache-arm.cc
+++ b/src/arm/stub-cache-arm.cc
@@ -202,10 +202,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
uint32_t mask = kPrimaryTableSize - 1;
// We shift out the last two bits because they are not part of the hash
and
// they are always 01 for maps.
- __ mov(scratch, Operand(scratch, LSR, kHeapObjectTagSize));
+ __ mov(scratch, Operand(scratch, LSR, kCacheIndexShift));
// Mask down the eor argument to the minimum to keep the immediate
// ARM-encodable.
- __ eor(scratch, scratch, Operand((flags >> kHeapObjectTagSize) & mask));
+ __ eor(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask));
// Prefer and_ to ubfx here because ubfx takes 2 cycles.
__ and_(scratch, scratch, Operand(mask));
@@ -222,9 +222,9 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
extra3);
// Primary miss: Compute hash for secondary probe.
- __ sub(scratch, scratch, Operand(name, LSR, kHeapObjectTagSize));
+ __ sub(scratch, scratch, Operand(name, LSR, kCacheIndexShift));
uint32_t mask2 = kSecondaryTableSize - 1;
- __ add(scratch, scratch, Operand((flags >> kHeapObjectTagSize) & mask2));
+ __ add(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask2));
__ and_(scratch, scratch, Operand(mask2));
// Probe the secondary table.
Index: src/arm64/stub-cache-arm64.cc
diff --git a/src/arm64/stub-cache-arm64.cc b/src/arm64/stub-cache-arm64.cc
index
c3b48a5815e6037c390e5367a7ad254eed9b4d39..0a672bcf2f0db225f8d62580c78a511a90412caf
100644
--- a/src/arm64/stub-cache-arm64.cc
+++ b/src/arm64/stub-cache-arm64.cc
@@ -177,7 +177,7 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ Add(scratch, scratch, extra);
__ Eor(scratch, scratch, flags);
// We shift out the last two bits because they are not part of the hash.
- __ Ubfx(scratch, scratch, kHeapObjectTagSize,
+ __ Ubfx(scratch, scratch, kCacheIndexShift,
CountTrailingZeros(kPrimaryTableSize, 64));
// Probe the primary table.
@@ -185,8 +185,8 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
scratch, extra, extra2, extra3);
// Primary miss: Compute hash for secondary table.
- __ Sub(scratch, scratch, Operand(name, LSR, kHeapObjectTagSize));
- __ Add(scratch, scratch, flags >> kHeapObjectTagSize);
+ __ Sub(scratch, scratch, Operand(name, LSR, kCacheIndexShift));
+ __ Add(scratch, scratch, flags >> kCacheIndexShift);
__ And(scratch, scratch, kSecondaryTableSize - 1);
// Probe the secondary table.
Index: src/ia32/stub-cache-ia32.cc
diff --git a/src/ia32/stub-cache-ia32.cc b/src/ia32/stub-cache-ia32.cc
index
a35be80deffac906f522aa68d8d5eb4f46e987e3..e02de20b156e3b9792a38a019d8ce5f031bcf6b2
100644
--- a/src/ia32/stub-cache-ia32.cc
+++ b/src/ia32/stub-cache-ia32.cc
@@ -205,10 +205,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ xor_(offset, flags);
// We mask out the last two bits because they are not part of the hash
and
// they are always 01 for maps. Also in the two 'and' instructions
below.
- __ and_(offset, (kPrimaryTableSize - 1) << kHeapObjectTagSize);
+ __ and_(offset, (kPrimaryTableSize - 1) << kCacheIndexShift);
// ProbeTable expects the offset to be pointer scaled, which it is,
because
// the heap object tag size is 2 and the pointer size log 2 is also 2.
- ASSERT(kHeapObjectTagSize == kPointerSizeLog2);
+ ASSERT(kCacheIndexShift == kPointerSizeLog2);
// Probe the primary table.
ProbeTable(isolate(), masm, flags, kPrimary, name, receiver, offset,
extra);
@@ -217,10 +217,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ mov(offset, FieldOperand(name, Name::kHashFieldOffset));
__ add(offset, FieldOperand(receiver, HeapObject::kMapOffset));
__ xor_(offset, flags);
- __ and_(offset, (kPrimaryTableSize - 1) << kHeapObjectTagSize);
+ __ and_(offset, (kPrimaryTableSize - 1) << kCacheIndexShift);
__ sub(offset, name);
__ add(offset, Immediate(flags));
- __ and_(offset, (kSecondaryTableSize - 1) << kHeapObjectTagSize);
+ __ and_(offset, (kSecondaryTableSize - 1) << kCacheIndexShift);
// Probe the secondary table.
ProbeTable(
Index: src/mips/stub-cache-mips.cc
diff --git a/src/mips/stub-cache-mips.cc b/src/mips/stub-cache-mips.cc
index
fc7315781c272dabbd9ab73700c5de2c446ae3d4..7fada5424b559f2fab6b72552e27fdf5dcfc6e41
100644
--- a/src/mips/stub-cache-mips.cc
+++ b/src/mips/stub-cache-mips.cc
@@ -196,8 +196,8 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
uint32_t mask = kPrimaryTableSize - 1;
// We shift out the last two bits because they are not part of the hash
and
// they are always 01 for maps.
- __ srl(scratch, scratch, kHeapObjectTagSize);
- __ Xor(scratch, scratch, Operand((flags >> kHeapObjectTagSize) & mask));
+ __ srl(scratch, scratch, kCacheIndexShift);
+ __ Xor(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask));
__ And(scratch, scratch, Operand(mask));
// Probe the primary table.
@@ -213,10 +213,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
extra3);
// Primary miss: Compute hash for secondary probe.
- __ srl(at, name, kHeapObjectTagSize);
+ __ srl(at, name, kCacheIndexShift);
__ Subu(scratch, scratch, at);
uint32_t mask2 = kSecondaryTableSize - 1;
- __ Addu(scratch, scratch, Operand((flags >> kHeapObjectTagSize) &
mask2));
+ __ Addu(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask2));
__ And(scratch, scratch, Operand(mask2));
// Probe the secondary table.
Index: src/mips64/stub-cache-mips64.cc
diff --git a/src/mips64/stub-cache-mips64.cc
b/src/mips64/stub-cache-mips64.cc
index
0979c1e622e210e552e6c8d59234b47237a1878e..39ae974c2bf5e93cb3a4904c012de9b48ec972bb
100644
--- a/src/mips64/stub-cache-mips64.cc
+++ b/src/mips64/stub-cache-mips64.cc
@@ -197,8 +197,8 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
uint64_t mask = kPrimaryTableSize - 1;
// We shift out the last two bits because they are not part of the hash
and
// they are always 01 for maps.
- __ dsrl(scratch, scratch, kHeapObjectTagSize);
- __ Xor(scratch, scratch, Operand((flags >> kHeapObjectTagSize) & mask));
+ __ dsrl(scratch, scratch, kCacheIndexShift);
+ __ Xor(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask));
__ And(scratch, scratch, Operand(mask));
// Probe the primary table.
@@ -214,10 +214,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
extra3);
// Primary miss: Compute hash for secondary probe.
- __ dsrl(at, name, kHeapObjectTagSize);
+ __ dsrl(at, name, kCacheIndexShift);
__ Dsubu(scratch, scratch, at);
uint64_t mask2 = kSecondaryTableSize - 1;
- __ Daddu(scratch, scratch, Operand((flags >> kHeapObjectTagSize) &
mask2));
+ __ Daddu(scratch, scratch, Operand((flags >> kCacheIndexShift) & mask2));
__ And(scratch, scratch, Operand(mask2));
// Probe the secondary table.
Index: src/stub-cache.h
diff --git a/src/stub-cache.h b/src/stub-cache.h
index
8c863e1bd895eb8e46c4896336393483248f40fa..4687c1cb2baf5992886d0cb500d42dd627f2686c
100644
--- a/src/stub-cache.h
+++ b/src/stub-cache.h
@@ -183,6 +183,11 @@ class StubCache {
static const int kInterceptorArgsHolderIndex = 3;
static const int kInterceptorArgsLength = 4;
+ // Setting the entry size such that the index is shifted by
Name::kHashShift
+ // is convenient; shifting down the length field (to extract the hash
code)
+ // automatically discards the hash bit field.
+ static const int kCacheIndexShift = Name::kHashShift;
+
private:
explicit StubCache(Isolate* isolate);
@@ -195,13 +200,9 @@ class StubCache {
// Hash algorithm for the primary table. This algorithm is replicated in
// assembler for every architecture. Returns an index into the table
that
- // is scaled by 1 << kHeapObjectTagSize.
+ // is scaled by 1 << kCacheIndexShift.
static int PrimaryOffset(Name* name, Code::Flags flags, Map* map) {
- // This works well because the heap object tag size and the hash
- // shift are equal. Shifting down the length field to get the
- // hash code would effectively throw away two bits of the hash
- // code.
- STATIC_ASSERT(kHeapObjectTagSize == Name::kHashShift);
+ STATIC_ASSERT(kCacheIndexShift == Name::kHashShift);
// Compute the hash of the name (use entire hash field).
ASSERT(name->HasHashCode());
uint32_t field = name->hash_field();
@@ -216,12 +217,12 @@ class StubCache {
(static_cast<uint32_t>(flags) & ~Code::kFlagsNotUsedInLookup);
// Base the offset on a simple combination of name, flags, and map.
uint32_t key = (map_low32bits + field) ^ iflags;
- return key & ((kPrimaryTableSize - 1) << kHeapObjectTagSize);
+ return key & ((kPrimaryTableSize - 1) << kCacheIndexShift);
}
// Hash algorithm for the secondary table. This algorithm is replicated
in
// assembler for every architecture. Returns an index into the table
that
- // is scaled by 1 << kHeapObjectTagSize.
+ // is scaled by 1 << kCacheIndexShift.
static int SecondaryOffset(Name* name, Code::Flags flags, int seed) {
// Use the seed from the primary cache in the secondary cache.
uint32_t name_low32bits =
@@ -231,7 +232,7 @@ class StubCache {
uint32_t iflags =
(static_cast<uint32_t>(flags) & ~Code::kFlagsNotUsedInLookup);
uint32_t key = (seed - name_low32bits) + iflags;
- return key & ((kSecondaryTableSize - 1) << kHeapObjectTagSize);
+ return key & ((kSecondaryTableSize - 1) << kCacheIndexShift);
}
// Compute the entry for a given offset in exactly the same way as
Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index
508b1b3a9a2f6a39847e2a8df71b1b74ca06fa15..74f756a969a79c059c790f0d9026bef517f46457
100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -24,13 +24,13 @@ static void ProbeTable(Isolate* isolate,
Register receiver,
Register name,
// The offset is scaled by 4, based on
- // kHeapObjectTagSize, which is two bits
+ // kCacheIndexShift, which is two bits
Register offset) {
// We need to scale up the pointer by 2 when the offset is scaled by less
// than the pointer size.
ASSERT(kPointerSize == kInt64Size
- ? kPointerSizeLog2 == kHeapObjectTagSize + 1
- : kPointerSizeLog2 == kHeapObjectTagSize);
+ ? kPointerSizeLog2 == StubCache::kCacheIndexShift + 1
+ : kPointerSizeLog2 == StubCache::kCacheIndexShift);
ScaleFactor scale_factor = kPointerSize == kInt64Size ? times_2 :
times_1;
ASSERT_EQ(3 * kPointerSize, sizeof(StubCache::Entry));
@@ -175,7 +175,7 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ xorp(scratch, Immediate(flags));
// We mask out the last two bits because they are not part of the hash
and
// they are always 01 for maps. Also in the two 'and' instructions
below.
- __ andp(scratch, Immediate((kPrimaryTableSize - 1) <<
kHeapObjectTagSize));
+ __ andp(scratch, Immediate((kPrimaryTableSize - 1) << kCacheIndexShift));
// Probe the primary table.
ProbeTable(isolate, masm, flags, kPrimary, receiver, name, scratch);
@@ -184,10 +184,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ movl(scratch, FieldOperand(name, Name::kHashFieldOffset));
__ addl(scratch, FieldOperand(receiver, HeapObject::kMapOffset));
__ xorp(scratch, Immediate(flags));
- __ andp(scratch, Immediate((kPrimaryTableSize - 1) <<
kHeapObjectTagSize));
+ __ andp(scratch, Immediate((kPrimaryTableSize - 1) << kCacheIndexShift));
__ subl(scratch, name);
__ addl(scratch, Immediate(flags));
- __ andp(scratch, Immediate((kSecondaryTableSize - 1) <<
kHeapObjectTagSize));
+ __ andp(scratch, Immediate((kSecondaryTableSize - 1) <<
kCacheIndexShift));
// Probe the secondary table.
ProbeTable(isolate, masm, flags, kSecondary, receiver, name, scratch);
Index: src/x87/stub-cache-x87.cc
diff --git a/src/x87/stub-cache-x87.cc b/src/x87/stub-cache-x87.cc
index
74275f937c27c128e75142c0b850b034ef84ce65..98d55f2ba3d100d0badeefd18cba931665069746
100644
--- a/src/x87/stub-cache-x87.cc
+++ b/src/x87/stub-cache-x87.cc
@@ -205,10 +205,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ xor_(offset, flags);
// We mask out the last two bits because they are not part of the hash
and
// they are always 01 for maps. Also in the two 'and' instructions
below.
- __ and_(offset, (kPrimaryTableSize - 1) << kHeapObjectTagSize);
+ __ and_(offset, (kPrimaryTableSize - 1) << kCacheIndexShift);
// ProbeTable expects the offset to be pointer scaled, which it is,
because
// the heap object tag size is 2 and the pointer size log 2 is also 2.
- ASSERT(kHeapObjectTagSize == kPointerSizeLog2);
+ ASSERT(kCacheIndexShift == kPointerSizeLog2);
// Probe the primary table.
ProbeTable(isolate(), masm, flags, kPrimary, name, receiver, offset,
extra);
@@ -217,10 +217,10 @@ void StubCache::GenerateProbe(MacroAssembler* masm,
__ mov(offset, FieldOperand(name, Name::kHashFieldOffset));
__ add(offset, FieldOperand(receiver, HeapObject::kMapOffset));
__ xor_(offset, flags);
- __ and_(offset, (kPrimaryTableSize - 1) << kHeapObjectTagSize);
+ __ and_(offset, (kPrimaryTableSize - 1) << kCacheIndexShift);
__ sub(offset, name);
__ add(offset, Immediate(flags));
- __ and_(offset, (kSecondaryTableSize - 1) << kHeapObjectTagSize);
+ __ and_(offset, (kSecondaryTableSize - 1) << kCacheIndexShift);
// Probe the secondary table.
ProbeTable(
--
--
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