Revision: 17084
Author: [email protected]
Date: Wed Oct 2 16:58:37 2013 UTC
Log: MIPS: Improve and simplify removal of unreachable code.
Port r17073 (ba68149)
Original commit message:
- Detect unreachable basic blocks of code either following an unconditional
deopt or after a provably untaken branch of HBranch or
HCompareObjectEqAndBranch instructions.
- Emit dummy uses in unreachable blocks during Hydrogen -> Lithium
translation.
BUG=chromium:258519
[email protected], [email protected]
Review URL: https://codereview.chromium.org/25708004
Patch from Balazs Kilvady <[email protected]>.
http://code.google.com/p/v8/source/detail?r=17084
Modified:
/branches/bleeding_edge/src/lithium-codegen.cc
/branches/bleeding_edge/src/mips/lithium-codegen-mips.cc
/branches/bleeding_edge/src/mips/lithium-codegen-mips.h
/branches/bleeding_edge/src/mips/lithium-mips.cc
/branches/bleeding_edge/src/mips/lithium-mips.h
=======================================
--- /branches/bleeding_edge/src/lithium-codegen.cc Wed Oct 2 15:27:51 2013
UTC
+++ /branches/bleeding_edge/src/lithium-codegen.cc Wed Oct 2 16:58:37 2013
UTC
@@ -39,7 +39,7 @@
#include "arm/lithium-arm.h"
#include "arm/lithium-codegen-arm.h"
#elif V8_TARGET_ARCH_MIPS
-#include "mips/lithium-codegeng.h"
+#include "mips/lithium-mips.h"
#include "mips/lithium-codegen-mips.h"
#else
#error Unsupported target architecture.
=======================================
--- /branches/bleeding_edge/src/mips/lithium-codegen-mips.cc Wed Oct 2
11:25:06 2013 UTC
+++ /branches/bleeding_edge/src/mips/lithium-codegen-mips.cc Wed Oct 2
16:58:37 2013 UTC
@@ -96,24 +96,6 @@
info()->set_bailout_reason(reason);
status_ = ABORTED;
}
-
-
-void LCodeGen::Comment(const char* format, ...) {
- if (!FLAG_code_comments) return;
- char buffer[4 * KB];
- StringBuilder builder(buffer, ARRAY_SIZE(buffer));
- va_list arguments;
- va_start(arguments, format);
- builder.AddFormattedList(format, arguments);
- va_end(arguments);
-
- // Copy the string before recording it in the assembler to avoid
- // issues when the stack allocated buffer goes out of scope.
- size_t length = builder.position();
- Vector<char> copy = Vector<char>::New(length + 1);
- OS::MemCopy(copy.start(), builder.Finalize(), copy.length());
- masm()->RecordComment(copy.start());
-}
bool LCodeGen::GeneratePrologue() {
@@ -263,37 +245,6 @@
ASSERT(slots >= 0);
__ Subu(sp, sp, Operand(slots * kPointerSize));
}
-
-
-bool LCodeGen::GenerateBody() {
- ASSERT(is_generating());
- bool emit_instructions = true;
- for (current_instruction_ = 0;
- !is_aborted() && current_instruction_ < instructions_->length();
- current_instruction_++) {
- LInstruction* instr = instructions_->at(current_instruction_);
-
- // Don't emit code for basic blocks with a replacement.
- if (instr->IsLabel()) {
- emit_instructions = !LLabel::cast(instr)->HasReplacement();
- }
- if (!emit_instructions) continue;
-
- if (FLAG_code_comments && instr->HasInterestingComment(this)) {
- Comment(";;; <@%d,#%d> %s",
- current_instruction_,
- instr->hydrogen_value()->id(),
- instr->Mnemonic());
- }
-
- RecordAndUpdatePosition(instr->position());
-
- instr->CompileToNative(this);
- }
- EnsureSpaceForLazyDeopt();
- last_lazy_deopt_pc_ = masm()->pc_offset();
- return !is_aborted();
-}
bool LCodeGen::GenerateDeferredCode() {
@@ -703,7 +654,7 @@
RelocInfo::Mode mode,
LInstruction* instr,
SafepointMode safepoint_mode) {
- EnsureSpaceForLazyDeopt();
+ EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
ASSERT(instr != NULL);
LPointerMap* pointers = instr->pointer_map();
RecordPosition(pointers->position());
@@ -2011,13 +1962,6 @@
}
-int LCodeGen::GetNextEmittedBlock() const {
- for (int i = current_block_ + 1; i < graph()->blocks()->length(); ++i) {
- if (!chunk_->GetLabel(i)->HasReplacement()) return i;
- }
- return -1;
-}
-
template<class InstrType>
void LCodeGen::EmitBranch(InstrType instr,
Condition condition,
@@ -5635,14 +5579,13 @@
}
-void LCodeGen::EnsureSpaceForLazyDeopt() {
+void LCodeGen::EnsureSpaceForLazyDeopt(int space_needed) {
if (info()->IsStub()) return;
// Ensure that we have enough space after the previous lazy-bailout
// instruction for patching the code here.
int current_pc = masm()->pc_offset();
- int patch_size = Deoptimizer::patch_size();
- if (current_pc < last_lazy_deopt_pc_ + patch_size) {
- int padding_size = last_lazy_deopt_pc_ + patch_size - current_pc;
+ if (current_pc < last_lazy_deopt_pc_ + space_needed) {
+ int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
ASSERT_EQ(0, padding_size % Assembler::kInstrSize);
while (padding_size > 0) {
__ nop();
@@ -5653,7 +5596,7 @@
void LCodeGen::DoLazyBailout(LLazyBailout* instr) {
- EnsureSpaceForLazyDeopt();
+ EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
last_lazy_deopt_pc_ = masm()->pc_offset();
ASSERT(instr->HasEnvironment());
LEnvironment* env = instr->environment();
@@ -5721,7 +5664,7 @@
CallCode(isolate()->builtins()->StackCheck(),
RelocInfo::CODE_TARGET,
instr);
- EnsureSpaceForLazyDeopt();
+ EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
last_lazy_deopt_pc_ = masm()->pc_offset();
__ bind(&done);
RegisterEnvironmentForDeoptimization(env, Safepoint::kLazyDeopt);
@@ -5733,7 +5676,7 @@
new(zone()) DeferredStackCheck(this, instr);
__ LoadRoot(at, Heap::kStackLimitRootIndex);
__ Branch(deferred_stack_check->entry(), lo, sp, Operand(at));
- EnsureSpaceForLazyDeopt();
+ EnsureSpaceForLazyDeopt(Deoptimizer::patch_size());
last_lazy_deopt_pc_ = masm()->pc_offset();
__ bind(instr->done_label());
deferred_stack_check->SetExit(instr->done_label());
=======================================
--- /branches/bleeding_edge/src/mips/lithium-codegen-mips.h Tue Oct 1
21:01:25 2013 UTC
+++ /branches/bleeding_edge/src/mips/lithium-codegen-mips.h Wed Oct 2
16:58:37 2013 UTC
@@ -31,6 +31,7 @@
#include "deoptimizer.h"
#include "mips/lithium-gap-resolver-mips.h"
#include "mips/lithium-mips.h"
+#include "lithium-codegen.h"
#include "safepoint-table.h"
#include "scopes.h"
#include "v8utils.h"
@@ -42,26 +43,18 @@
class LDeferredCode;
class SafepointGenerator;
-class LCodeGen V8_FINAL BASE_EMBEDDED {
+class LCodeGen: public LCodeGenBase {
public:
LCodeGen(LChunk* chunk, MacroAssembler* assembler, CompilationInfo* info)
- : zone_(info->zone()),
- chunk_(static_cast<LPlatformChunk*>(chunk)),
- masm_(assembler),
- info_(info),
- current_block_(-1),
- current_instruction_(-1),
- instructions_(chunk->instructions()),
+ : LCodeGenBase(chunk, assembler, info),
deoptimizations_(4, info->zone()),
deopt_jump_table_(4, info->zone()),
deoptimization_literals_(8, info->zone()),
inlined_function_count_(0),
scope_(info->scope()),
- status_(UNUSED),
translations_(info->zone()),
deferred_(8, info->zone()),
osr_pc_offset_(-1),
- last_lazy_deopt_pc_(0),
frame_is_built_(false),
safepoints_(info->zone()),
resolver_(this),
@@ -70,14 +63,6 @@
PopulateDeoptimizationLiteralsWithInlinedFunctions();
}
-
- // Simple accessors.
- MacroAssembler* masm() const { return masm_; }
- CompilationInfo* info() const { return info_; }
- Isolate* isolate() const { return info_->isolate(); }
- Factory* factory() const { return isolate()->factory(); }
- Heap* heap() const { return isolate()->heap(); }
- Zone* zone() const { return zone_; }
int LookupDestination(int block_id) const {
return chunk()->LookupDestination(block_id);
@@ -177,31 +162,16 @@
#undef DECLARE_DO
private:
- enum Status {
- UNUSED,
- GENERATING,
- DONE,
- ABORTED
- };
-
- bool is_unused() const { return status_ == UNUSED; }
- bool is_generating() const { return status_ == GENERATING; }
- bool is_done() const { return status_ == DONE; }
- bool is_aborted() const { return status_ == ABORTED; }
-
StrictModeFlag strict_mode_flag() const {
return info()->is_classic_mode() ? kNonStrictMode : kStrictMode;
}
- LPlatformChunk* chunk() const { return chunk_; }
Scope* scope() const { return scope_; }
- HGraph* graph() const { return chunk()->graph(); }
Register scratch0() { return kLithiumScratchReg; }
Register scratch1() { return kLithiumScratchReg2; }
DoubleRegister double_scratch0() { return kLithiumScratchDouble; }
- int GetNextEmittedBlock() const;
LInstruction* GetNextInstruction();
void EmitClassOfTest(Label* if_true,
@@ -214,14 +184,12 @@
int GetStackSlotCount() const { return chunk()->spill_slot_count(); }
void Abort(BailoutReason reason);
- void FPRINTF_CHECKING Comment(const char* format, ...);
void AddDeferredCode(LDeferredCode* code) { deferred_.Add(code, zone());
}
// Code generation passes. Returns true if code generation should
// continue.
bool GeneratePrologue();
- bool GenerateBody();
bool GenerateDeferredCode();
bool GenerateDeoptJumpTable();
bool GenerateSafepointTable();
@@ -328,7 +296,7 @@
int arguments,
Safepoint::DeoptMode mode);
void RecordPosition(int position);
- void RecordAndUpdatePosition(int position);
+ void RecordAndUpdatePosition(int position) V8_OVERRIDE;
static Condition TokenToCondition(Token::Value op, bool is_unsigned);
void EmitGoto(int block);
@@ -407,7 +375,7 @@
LEnvironment* environment);
- void EnsureSpaceForLazyDeopt();
+ void EnsureSpaceForLazyDeopt(int space_needed) V8_OVERRIDE;
void DoLoadKeyedExternalArray(LLoadKeyed* instr);
void DoLoadKeyedFixedDoubleArray(LLoadKeyed* instr);
void DoLoadKeyedFixedArray(LLoadKeyed* instr);
@@ -415,24 +383,14 @@
void DoStoreKeyedFixedDoubleArray(LStoreKeyed* instr);
void DoStoreKeyedFixedArray(LStoreKeyed* instr);
- Zone* zone_;
- LPlatformChunk* const chunk_;
- MacroAssembler* const masm_;
- CompilationInfo* const info_;
-
- int current_block_;
- int current_instruction_;
- const ZoneList<LInstruction*>* instructions_;
ZoneList<LEnvironment*> deoptimizations_;
ZoneList<Deoptimizer::JumpTableEntry> deopt_jump_table_;
ZoneList<Handle<Object> > deoptimization_literals_;
int inlined_function_count_;
Scope* const scope_;
- Status status_;
TranslationBuffer translations_;
ZoneList<LDeferredCode*> deferred_;
int osr_pc_offset_;
- int last_lazy_deopt_pc_;
bool frame_is_built_;
// Builder that keeps track of safepoints in the code. The table
=======================================
--- /branches/bleeding_edge/src/mips/lithium-mips.cc Tue Oct 1 21:01:25
2013 UTC
+++ /branches/bleeding_edge/src/mips/lithium-mips.cc Wed Oct 2 16:58:37
2013 UTC
@@ -865,7 +865,22 @@
HInstruction* old_current = current_instruction_;
current_instruction_ = current;
if (current->has_position()) position_ = current->position();
- LInstruction* instr = current->CompileToLithium(this);
+
+ LInstruction* instr = NULL;
+ if (current->CanReplaceWithDummyUses()) {
+ HValue* first_operand = current->OperandCount() == 0
+ ? graph()->GetConstant1()
+ : current->OperandAt(0);
+ instr = DefineAsRegister(new(zone()) LDummyUse(UseAny(first_operand)));
+ for (int i = 1; i < current->OperandCount(); ++i) {
+ LInstruction* dummy =
+ new(zone()) LDummyUse(UseAny(current->OperandAt(i)));
+ dummy->set_hydrogen_value(current);
+ chunk_->AddInstruction(dummy, current_block_);
+ }
+ } else {
+ instr = current->CompileToLithium(this);
+ }
if (instr != NULL) {
// Associate the hydrogen instruction first, since we may need it for
@@ -999,19 +1014,15 @@
LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
- return new(zone()) LGoto(instr->FirstSuccessor()->block_id());
+ return new(zone()) LGoto(instr->FirstSuccessor());
}
LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
+ LInstruction* goto_instr = CheckElideControlInstruction(instr);
+ if (goto_instr != NULL) return goto_instr;
+
HValue* value = instr->value();
- if (value->EmitAtUses()) {
- HBasicBlock* successor = HConstant::cast(value)->BooleanValue()
- ? instr->FirstSuccessor()
- : instr->SecondSuccessor();
- return new(zone()) LGoto(successor->block_id());
- }
-
LBranch* result = new(zone()) LBranch(UseRegister(value));
// Tagged values that are not known smis or booleans require a
// deoptimization environment. If the instruction is generic no
@@ -1690,6 +1701,8 @@
LInstruction* LChunkBuilder::DoCompareObjectEqAndBranch(
HCompareObjectEqAndBranch* instr) {
+ LInstruction* goto_instr = CheckElideControlInstruction(instr);
+ if (goto_instr != NULL) return goto_instr;
LOperand* left = UseRegisterAtStart(instr->left());
LOperand* right = UseRegisterAtStart(instr->right());
return new(zone()) LCmpObjectEqAndBranch(left, right);
=======================================
--- /branches/bleeding_edge/src/mips/lithium-mips.h Tue Oct 1 21:01:25
2013 UTC
+++ /branches/bleeding_edge/src/mips/lithium-mips.h Wed Oct 2 16:58:37
2013 UTC
@@ -401,17 +401,17 @@
class LGoto V8_FINAL : public LTemplateInstruction<0, 0, 0> {
public:
- explicit LGoto(int block_id) : block_id_(block_id) { }
+ explicit LGoto(HBasicBlock* block) : block_(block) { }
virtual bool HasInterestingComment(LCodeGen* gen) const V8_OVERRIDE;
DECLARE_CONCRETE_INSTRUCTION(Goto, "goto")
virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
virtual bool IsControl() const V8_OVERRIDE { return true; }
- int block_id() const { return block_id_; }
+ int block_id() const { return block_->block_id(); }
private:
- int block_id_;
+ HBasicBlock* block_;
};
@@ -2732,6 +2732,8 @@
// Build the sequence for the graph.
LPlatformChunk* Build();
+ LInstruction* CheckElideControlInstruction(HControlInstruction* instr);
+
// Declare methods that deal with the individual node types.
#define DECLARE_DO(type) LInstruction* Do##type(H##type* node);
HYDROGEN_CONCRETE_INSTRUCTION_LIST(DECLARE_DO)
--
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