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Unified Diff: src/arm/assembler-arm-inl.h

Issue 284153004: Avoid flushing the icache unnecessarily when updating target addresses in code. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Update SKIP_ICACHE_FLUSH_IF_ATOMIC to only skip when patching a single instruction. Created 6 years, 7 months ago
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Index: src/arm/assembler-arm-inl.h
diff --git a/src/arm/assembler-arm-inl.h b/src/arm/assembler-arm-inl.h
index c9e32cbf3f106f706699cfd1a39005e8e78491ed..21baeb2bccb3e1c36216cfc25634915e2b3786dc 100644
--- a/src/arm/assembler-arm-inl.h
+++ b/src/arm/assembler-arm-inl.h
@@ -142,10 +142,13 @@ int RelocInfo::target_address_size() {
}
-void RelocInfo::set_target_address(Address target, WriteBarrierMode mode) {
+void RelocInfo::set_target_address(Address target,
+ WriteBarrierMode write_barrier_mode,
+ ICacheFlushMode icache_flush_mode) {
ASSERT(IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_));
- Assembler::set_target_address_at(pc_, host_, target);
- if (mode == UPDATE_WRITE_BARRIER && host() != NULL && IsCodeTarget(rmode_)) {
+ Assembler::set_target_address_at(pc_, host_, target, icache_flush_mode);
+ if (write_barrier_mode == UPDATE_WRITE_BARRIER &&
+ host() != NULL && IsCodeTarget(rmode_)) {
Object* target_code = Code::GetCodeFromTargetAddress(target);
host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(
host(), this, HeapObject::cast(target_code));
@@ -166,12 +169,15 @@ Handle<Object> RelocInfo::target_object_handle(Assembler* origin) {
}
-void RelocInfo::set_target_object(Object* target, WriteBarrierMode mode) {
+void RelocInfo::set_target_object(Object* target,
+ WriteBarrierMode write_barrier_mode,
+ ICacheFlushMode icache_flush_mode) {
ASSERT(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
ASSERT(!target->IsConsString());
Assembler::set_target_address_at(pc_, host_,
- reinterpret_cast<Address>(target));
- if (mode == UPDATE_WRITE_BARRIER &&
+ reinterpret_cast<Address>(target),
+ icache_flush_mode);
+ if (write_barrier_mode == UPDATE_WRITE_BARRIER &&
host() != NULL &&
target->IsHeapObject()) {
host()->GetHeap()->incremental_marking()->RecordWrite(
@@ -193,9 +199,11 @@ Address RelocInfo::target_runtime_entry(Assembler* origin) {
void RelocInfo::set_target_runtime_entry(Address target,
- WriteBarrierMode mode) {
+ WriteBarrierMode write_barrier_mode,
+ ICacheFlushMode icache_flush_mode) {
ASSERT(IsRuntimeEntry(rmode_));
- if (target_address() != target) set_target_address(target, mode);
+ if (target_address() != target)
+ set_target_address(target, write_barrier_mode, icache_flush_mode);
}
@@ -212,11 +220,13 @@ Cell* RelocInfo::target_cell() {
}
-void RelocInfo::set_target_cell(Cell* cell, WriteBarrierMode mode) {
+void RelocInfo::set_target_cell(Cell* cell,
+ WriteBarrierMode write_barrier_mode,
+ ICacheFlushMode icache_flush_mode) {
ASSERT(rmode_ == RelocInfo::CELL);
Address address = cell->address() + Cell::kValueOffset;
Memory::Address_at(pc_) = address;
- if (mode == UPDATE_WRITE_BARRIER && host() != NULL) {
+ if (write_barrier_mode == UPDATE_WRITE_BARRIER && host() != NULL) {
// TODO(1550) We are passing NULL as a slot because cell can never be on
// evacuation candidate.
host()->GetHeap()->incremental_marking()->RecordWrite(
@@ -500,30 +510,51 @@ void Assembler::deserialization_set_special_target_at(
}
+static uint32_t ExtractMovwImmediate(Instr instruction) {
Rodolph Perfetta 2014/05/19 12:38:38 the Instruction class has a ImmedMovwMovtValue met
rmcilroy 2014/05/19 16:52:16 Ack (no longer applicable).
+ ASSERT(Assembler::IsMovW(instruction) || Assembler::IsMovT(instruction));
+ return ((instruction & 0xf0000) >> 4) | (instruction & 0xfff);
+}
+
+
static Instr EncodeMovwImmediate(uint32_t immediate) {
ASSERT(immediate < 0x10000);
return ((immediate & 0xf000) << 4) | (immediate & 0xfff);
}
+static Instr PatchMovwImmediate(Instr instruction, uint32_t immediate) {
+ instruction &= ~EncodeMovwImmediate(0xffff);
+ return instruction | EncodeMovwImmediate(immediate);
+}
+
+
void Assembler::set_target_address_at(Address pc,
ConstantPoolArray* constant_pool,
- Address target) {
+ Address target,
+ ICacheFlushMode icache_flush_mode) {
if (IsMovW(Memory::int32_at(pc))) {
ASSERT(IsMovT(Memory::int32_at(pc + kInstrSize)));
uint32_t* instr_ptr = reinterpret_cast<uint32_t*>(pc);
- uint32_t immediate = reinterpret_cast<uint32_t>(target);
- uint32_t intermediate = instr_ptr[0];
- intermediate &= ~EncodeMovwImmediate(0xFFFF);
- intermediate |= EncodeMovwImmediate(immediate & 0xFFFF);
- instr_ptr[0] = intermediate;
- intermediate = instr_ptr[1];
- intermediate &= ~EncodeMovwImmediate(0xFFFF);
- intermediate |= EncodeMovwImmediate(immediate >> 16);
- instr_ptr[1] = intermediate;
+ uint32_t immediate_high = reinterpret_cast<uint32_t>(target) >> 16;
+ uint32_t immediate_low = reinterpret_cast<uint32_t>(target) & 0xFFFF;
+ int instructions_patched = 0;
+ if (ExtractMovwImmediate(instr_ptr[0]) != immediate_low) {
+ instr_ptr[0] = PatchMovwImmediate(instr_ptr[0], immediate_low);
+ instructions_patched++;
+ }
+ if (ExtractMovwImmediate(instr_ptr[1]) != immediate_high) {
+ instr_ptr[1] = PatchMovwImmediate(instr_ptr[1], immediate_high);
+ instructions_patched++;
+ }
ASSERT(IsMovW(Memory::int32_at(pc)));
ASSERT(IsMovT(Memory::int32_at(pc + kInstrSize)));
- CPU::FlushICache(pc, 2 * kInstrSize);
+ if (icache_flush_mode == SKIP_ICACHE_FLUSH ||
+ (icache_flush_mode == SKIP_ICACHE_FLUSH_IF_ATOMIC &&
+ instructions_patched <= 1)) {
+ // We can skip the icache flush in these cases.
+ } else {
+ CPU::FlushICache(pc, 2 * kInstrSize);
+ }
} else if (FLAG_enable_ool_constant_pool) {
ASSERT(IsLdrPpImmediateOffset(Memory::int32_at(pc)));
Memory::Address_at(
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