c01bfa9af9
This CL implements an assembly order optimization that moves blocks that end a loop with an unconditional backedge to the beginning of the loop, saving a branch. R=jarin@chromium.org,mstarzinger@chromium.org BUG=v8:8423 Change-Id: I8a5d25f5472d71227af0f623277ea8d0a8d69867 Reviewed-on: https://chromium-review.googlesource.com/c/1335944 Commit-Queue: Ben Titzer <titzer@chromium.org> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org> Cr-Commit-Position: refs/heads/master@{#57572}
114 lines
4.2 KiB
C++
114 lines
4.2 KiB
C++
// Copyright 2017 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/compiler/backend/instruction-scheduler.h"
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#include "src/compiler/backend/instruction-selector-impl.h"
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#include "src/compiler/backend/instruction.h"
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#include "test/cctest/cctest.h"
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namespace v8 {
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namespace internal {
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namespace compiler {
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// Create InstructionBlocks with a single block.
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InstructionBlocks* CreateSingleBlock(Zone* zone) {
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InstructionBlock* block = new (zone)
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InstructionBlock(zone, RpoNumber::FromInt(0), RpoNumber::Invalid(),
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RpoNumber::Invalid(), false, false);
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InstructionBlocks* blocks = zone->NewArray<InstructionBlocks>(1);
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new (blocks) InstructionBlocks(1, block, zone);
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return blocks;
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}
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// Wrapper around the InstructionScheduler.
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class InstructionSchedulerTester {
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public:
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InstructionSchedulerTester()
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: scope_(),
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blocks_(CreateSingleBlock(scope_.main_zone())),
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sequence_(scope_.main_isolate(), scope_.main_zone(), blocks_),
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scheduler_(scope_.main_zone(), &sequence_) {}
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void StartBlock() { scheduler_.StartBlock(RpoNumber::FromInt(0)); }
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void EndBlock() { scheduler_.EndBlock(RpoNumber::FromInt(0)); }
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void AddInstruction(Instruction* instr) { scheduler_.AddInstruction(instr); }
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void AddTerminator(Instruction* instr) { scheduler_.AddTerminator(instr); }
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void CheckHasSideEffect(Instruction* instr) {
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CHECK(scheduler_.HasSideEffect(instr));
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}
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void CheckIsDeopt(Instruction* instr) { CHECK(instr->IsDeoptimizeCall()); }
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void CheckInSuccessors(Instruction* instr, Instruction* successor) {
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InstructionScheduler::ScheduleGraphNode* node = GetNode(instr);
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InstructionScheduler::ScheduleGraphNode* succ_node = GetNode(successor);
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ZoneDeque<InstructionScheduler::ScheduleGraphNode*>& successors =
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node->successors();
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CHECK_NE(std::find(successors.begin(), successors.end(), succ_node),
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successors.end());
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}
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Zone* zone() { return scope_.main_zone(); }
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private:
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InstructionScheduler::ScheduleGraphNode* GetNode(Instruction* instr) {
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for (auto node : scheduler_.graph_) {
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if (node->instruction() == instr) return node;
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}
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return nullptr;
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}
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HandleAndZoneScope scope_;
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InstructionBlocks* blocks_;
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InstructionSequence sequence_;
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InstructionScheduler scheduler_;
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};
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TEST(DeoptInMiddleOfBasicBlock) {
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InstructionSchedulerTester tester;
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Zone* zone = tester.zone();
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tester.StartBlock();
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InstructionCode jmp_opcode = kArchJmp;
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// Dummy node for FlagsContinuation::ForDeoptimize (which won't accept
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// nullptr).
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Node* node = Node::New(zone, 0, nullptr, 0, nullptr, false);
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VectorSlotPair feedback;
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FlagsContinuation cont = FlagsContinuation::ForDeoptimize(
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kEqual, DeoptimizeKind::kEager, DeoptimizeReason::kUnknown, feedback,
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node);
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jmp_opcode = cont.Encode(jmp_opcode);
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Instruction* jmp_inst = Instruction::New(zone, jmp_opcode);
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tester.CheckIsDeopt(jmp_inst);
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tester.AddInstruction(jmp_inst);
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Instruction* side_effect_inst = Instruction::New(zone, kArchPrepareTailCall);
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tester.CheckHasSideEffect(side_effect_inst);
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tester.AddInstruction(side_effect_inst);
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Instruction* other_jmp_inst = Instruction::New(zone, jmp_opcode);
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tester.CheckIsDeopt(other_jmp_inst);
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tester.AddInstruction(other_jmp_inst);
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Instruction* ret_inst = Instruction::New(zone, kArchRet);
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tester.AddTerminator(ret_inst);
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// Check that an instruction with a side effect is a successor of the deopt.
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tester.CheckInSuccessors(jmp_inst, side_effect_inst);
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// Check that the second deopt is a successor of the first deopt.
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tester.CheckInSuccessors(jmp_inst, other_jmp_inst);
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// Check that the second deopt is a successor of the side-effect instruction.
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tester.CheckInSuccessors(side_effect_inst, other_jmp_inst);
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// Check that the block terminator is a successor of all other instructions.
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tester.CheckInSuccessors(jmp_inst, ret_inst);
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tester.CheckInSuccessors(side_effect_inst, ret_inst);
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tester.CheckInSuccessors(other_jmp_inst, ret_inst);
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// Schedule block.
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tester.EndBlock();
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}
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} // namespace compiler
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} // namespace internal
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} // namespace v8
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