Source/JavaScriptCore/b3/air/AirGenerate.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "AirGenerate.h"

 #if ENABLE(B3_JIT)

 #include "AirAllocateStack.h"
 #include "AirCode.h"
 #include "AirDumpAsJS.h"
 #include "AirEliminateDeadCode.h"
 #include "AirFixObviousSpills.h"
 #include "AirFixPartialRegisterStalls.h"
 #include "AirGenerationContext.h"
 #include "AirHandleCalleeSaves.h"
 #include "AirIteratedRegisterCoalescing.h"
 #include "AirLogRegisterPressure.h"
 #include "AirLowerAfterRegAlloc.h"
 #include "AirLowerMacros.h"
 #include "AirOpcodeUtils.h"
 #include "AirOptimizeBlockOrder.h"
 #include "AirReportUsedRegisters.h"
 #include "AirSimplifyCFG.h"
 #include "AirSpillEverything.h"
 #include "AirValidate.h"
 #include "B3Common.h"
 #include "B3IndexMap.h"
 #include "B3Procedure.h"
 #include "B3TimingScope.h"
 #include "CCallHelpers.h"
 #include "DisallowMacroScratchRegisterUsage.h"

 namespace JSC { namespace B3 { namespace Air {

 void prepareForGeneration(Code& code)
 {
     TimingScope timingScope("Air::prepareForGeneration");

     // We don't expect the incoming code to have predecessors computed.
     code.resetReachability();

     if (shouldValidateIR())
         validate(code);

     // If we're doing super verbose dumping, the phase scope of any phase will already do a dump.
     if (shouldDumpIR(AirMode) && !shouldDumpIRAtEachPhase(AirMode)) {
         dataLog("Initial air:\n");
         dataLog(code);
     }

     lowerMacros(code);

     // This is where we run our optimizations and transformations.
     // FIXME: Add Air optimizations.
     // https://bugs.webkit.org/show_bug.cgi?id=150456

     eliminateDeadCode(code);

     // Register allocation for all the Tmps that do not have a corresponding machine register.
     // After this phase, every Tmp has a reg.
     //
     // For debugging, you can use spillEverything() to put everything to the stack between each Inst.
     if (Options::airSpillsEverything())
         spillEverything(code);
     else
         iteratedRegisterCoalescing(code);

     if (Options::logAirRegisterPressure()) {
         dataLog("Register pressure after register allocation:\n");
         logRegisterPressure(code);
     }

     // This replaces uses of spill slots with registers or constants if possible. It does this by
     // minimizing the amount that we perturb the already-chosen register allocation. It may extend
     // the live ranges of registers though.
     fixObviousSpills(code);

     lowerAfterRegAlloc(code);

     // Prior to this point the prologue and epilogue is implicit. This makes it explicit. It also
     // does things like identify which callee-saves we're using and saves them.
     handleCalleeSaves(code);

     if (Options::dumpAirAsJSBeforeAllocateStack()) {
         dataLog("Dumping Air as JS before allocateStack:\n");
         dumpAsJS(code, WTF::dataFile());
         dataLog("Air hash: ", code.jsHash(), "\n");
     }

     // This turns all Stack and CallArg Args into Addr args that use the frame pointer. It does
     // this by first-fit allocating stack slots. It should be pretty darn close to optimal, so we
     // shouldn't have to worry about this very much.
     allocateStack(code);

     if (Options::dumpAirAfterAllocateStack()) {
         dataLog("Dumping Air after allocateStack:\n");
         dataLog(code);
         dataLog("Air hash: ", code.jsHash(), "\n");
     }

     // If we coalesced moves then we can unbreak critical edges. This is the main reason for this
     // phase.
     simplifyCFG(code);

     // This sorts the basic blocks in Code to achieve an ordering that maximizes the likelihood that a high
     // frequency successor is also the fall-through target.
     optimizeBlockOrder(code);

     // This is needed to satisfy a requirement of B3::StackmapValue.
     reportUsedRegisters(code);

     // Attempt to remove false dependencies between instructions created by partial register changes.
     // This must be executed as late as possible as it depends on the instructions order and register
     // use. We _must_ run this after reportUsedRegisters(), since that kills variable assignments
     // that seem dead. Luckily, this phase does not change register liveness, so that's OK.
     fixPartialRegisterStalls(code);

     if (shouldValidateIR())
         validate(code);

     // Do a final dump of Air. Note that we have to do this even if we are doing per-phase dumping,
     // since the final generation is not a phase.
     if (shouldDumpIR(AirMode)) {
         dataLog("Air after ", code.lastPhaseName(), ", before generation:\n");
         dataLog(code);
     }
 }

 void generate(Code& code, CCallHelpers& jit)
 {
     TimingScope timingScope("Air::generate");

     DisallowMacroScratchRegisterUsage disallowScratch(jit);

     // And now, we generate code.
     jit.emitFunctionPrologue();
     if (code.frameSize())
         jit.addPtr(CCallHelpers::TrustedImm32(-code.frameSize()), MacroAssembler::stackPointerRegister);

     auto argFor = [&] (const RegisterAtOffset& entry) -> CCallHelpers::Address {
         return CCallHelpers::Address(GPRInfo::callFrameRegister, entry.offset());
     };

     for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) {
         if (entry.reg().isGPR())
             jit.storePtr(entry.reg().gpr(), argFor(entry));
         else
             jit.storeDouble(entry.reg().fpr(), argFor(entry));
     }

     GenerationContext context;
     context.code = &code;
     IndexMap<BasicBlock, CCallHelpers::Label> blockLabels(code.size());
     IndexMap<BasicBlock, CCallHelpers::JumpList> blockJumps(code.size());

     auto link = [&] (CCallHelpers::Jump jump, BasicBlock* target) {
         if (blockLabels[target].isSet()) {
             jump.linkTo(blockLabels[target], &jit);
             return;
         }

         blockJumps[target].append(jump);
     };

     PCToOriginMap& pcToOriginMap = code.proc().pcToOriginMap();
     auto addItem = [&] (Inst& inst) {
         if (!inst.origin) {
             pcToOriginMap.appendItem(jit.label(), Origin());
             return;
         }
         pcToOriginMap.appendItem(jit.label(), inst.origin->origin());
     };

     for (BasicBlock* block : code) {
         blockJumps[block].link(&jit);
         blockLabels[block] = jit.label();
         ASSERT(block->size() >= 1);
         for (unsigned i = 0; i < block->size() - 1; ++i) {
             Inst& inst = block->at(i);
             addItem(inst);
             CCallHelpers::Jump jump = inst.generate(jit, context);
             ASSERT_UNUSED(jump, !jump.isSet());
         }

         if (block->last().opcode == Jump
             && block->successorBlock(0) == code.findNextBlock(block))
             continue;

         addItem(block->last());

         if (isReturn(block->last().opcode)) {
             // We currently don't represent the full prologue/epilogue in Air, so we need to
             // have this override.
             if (code.frameSize()) {
                 for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) {
                     if (entry.reg().isGPR())
                         jit.loadPtr(argFor(entry), entry.reg().gpr());
                     else
                         jit.loadDouble(argFor(entry), entry.reg().fpr());
                 }
                 jit.emitFunctionEpilogue();
             } else
                 jit.emitFunctionEpilogueWithEmptyFrame();
             jit.ret();
             addItem(block->last());
             continue;
         }

         CCallHelpers::Jump jump = block->last().generate(jit, context);
         switch (block->numSuccessors()) {
         case 0:
             ASSERT(!jump.isSet());
             break;
         case 1:
             link(jump, block->successorBlock(0));
             break;
         case 2:
             link(jump, block->successorBlock(0));
             if (block->successorBlock(1) != code.findNextBlock(block))
                 link(jit.jump(), block->successorBlock(1));
             break;
         default:
             RELEASE_ASSERT_NOT_REACHED();
             break;
         }
         addItem(block->last());
     }

     pcToOriginMap.appendItem(jit.label(), Origin());
     // FIXME: Make late paths have Origins: https://bugs.webkit.org/show_bug.cgi?id=153689
     for (auto& latePath : context.latePaths)
         latePath->run(jit, context);
     pcToOriginMap.appendItem(jit.label(), Origin());
 }

 } } } // namespace JSC::B3::Air

 #endif // ENABLE(B3_JIT)
	/*
	* Copyright (C) 2015-2016 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
	* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "AirGenerate.h"

	#if ENABLE(B3_JIT)

	#include "AirAllocateStack.h"
	#include "AirCode.h"
	#include "AirDumpAsJS.h"
	#include "AirEliminateDeadCode.h"
	#include "AirFixObviousSpills.h"
	#include "AirFixPartialRegisterStalls.h"
	#include "AirGenerationContext.h"
	#include "AirHandleCalleeSaves.h"
	#include "AirIteratedRegisterCoalescing.h"
	#include "AirLogRegisterPressure.h"
	#include "AirLowerAfterRegAlloc.h"
	#include "AirLowerMacros.h"
	#include "AirOpcodeUtils.h"
	#include "AirOptimizeBlockOrder.h"
	#include "AirReportUsedRegisters.h"
	#include "AirSimplifyCFG.h"
	#include "AirSpillEverything.h"
	#include "AirValidate.h"
	#include "B3Common.h"
	#include "B3IndexMap.h"
	#include "B3Procedure.h"
	#include "B3TimingScope.h"
	#include "CCallHelpers.h"
	#include "DisallowMacroScratchRegisterUsage.h"

	namespace JSC { namespace B3 { namespace Air {

	void prepareForGeneration(Code& code)
	{
	TimingScope timingScope("Air::prepareForGeneration");

	// We don't expect the incoming code to have predecessors computed.
	code.resetReachability();

	if (shouldValidateIR())
	validate(code);

	// If we're doing super verbose dumping, the phase scope of any phase will already do a dump.
	if (shouldDumpIR(AirMode) && !shouldDumpIRAtEachPhase(AirMode)) {
	dataLog("Initial air:\n");
	dataLog(code);
	}

	lowerMacros(code);

	// This is where we run our optimizations and transformations.
	// FIXME: Add Air optimizations.
	// https://bugs.webkit.org/show_bug.cgi?id=150456

	eliminateDeadCode(code);

	// Register allocation for all the Tmps that do not have a corresponding machine register.
	// After this phase, every Tmp has a reg.
	//
	// For debugging, you can use spillEverything() to put everything to the stack between each Inst.
	if (Options::airSpillsEverything())
	spillEverything(code);
	else
	iteratedRegisterCoalescing(code);

	if (Options::logAirRegisterPressure()) {
	dataLog("Register pressure after register allocation:\n");
	logRegisterPressure(code);
	}

	// This replaces uses of spill slots with registers or constants if possible. It does this by
	// minimizing the amount that we perturb the already-chosen register allocation. It may extend
	// the live ranges of registers though.
	fixObviousSpills(code);

	lowerAfterRegAlloc(code);

	// Prior to this point the prologue and epilogue is implicit. This makes it explicit. It also
	// does things like identify which callee-saves we're using and saves them.
	handleCalleeSaves(code);

	if (Options::dumpAirAsJSBeforeAllocateStack()) {
	dataLog("Dumping Air as JS before allocateStack:\n");
	dumpAsJS(code, WTF::dataFile());
	dataLog("Air hash: ", code.jsHash(), "\n");
	}

	// This turns all Stack and CallArg Args into Addr args that use the frame pointer. It does
	// this by first-fit allocating stack slots. It should be pretty darn close to optimal, so we
	// shouldn't have to worry about this very much.
	allocateStack(code);

	if (Options::dumpAirAfterAllocateStack()) {
	dataLog("Dumping Air after allocateStack:\n");
	dataLog(code);
	dataLog("Air hash: ", code.jsHash(), "\n");
	}

	// If we coalesced moves then we can unbreak critical edges. This is the main reason for this
	// phase.
	simplifyCFG(code);

	// This sorts the basic blocks in Code to achieve an ordering that maximizes the likelihood that a high
	// frequency successor is also the fall-through target.
	optimizeBlockOrder(code);

	// This is needed to satisfy a requirement of B3::StackmapValue.
	reportUsedRegisters(code);

	// Attempt to remove false dependencies between instructions created by partial register changes.
	// This must be executed as late as possible as it depends on the instructions order and register
	// use. We _must_ run this after reportUsedRegisters(), since that kills variable assignments
	// that seem dead. Luckily, this phase does not change register liveness, so that's OK.
	fixPartialRegisterStalls(code);

	if (shouldValidateIR())
	validate(code);

	// Do a final dump of Air. Note that we have to do this even if we are doing per-phase dumping,
	// since the final generation is not a phase.
	if (shouldDumpIR(AirMode)) {
	dataLog("Air after ", code.lastPhaseName(), ", before generation:\n");
	dataLog(code);
	}
	}

	void generate(Code& code, CCallHelpers& jit)
	{
	TimingScope timingScope("Air::generate");

	DisallowMacroScratchRegisterUsage disallowScratch(jit);

	// And now, we generate code.
	jit.emitFunctionPrologue();
	if (code.frameSize())
	jit.addPtr(CCallHelpers::TrustedImm32(-code.frameSize()), MacroAssembler::stackPointerRegister);

	auto argFor = [&] (const RegisterAtOffset& entry) -> CCallHelpers::Address {
	return CCallHelpers::Address(GPRInfo::callFrameRegister, entry.offset());
	};

	for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) {
	if (entry.reg().isGPR())
	jit.storePtr(entry.reg().gpr(), argFor(entry));
	else
	jit.storeDouble(entry.reg().fpr(), argFor(entry));
	}

	GenerationContext context;
	context.code = &code;
	IndexMap<BasicBlock, CCallHelpers::Label> blockLabels(code.size());
	IndexMap<BasicBlock, CCallHelpers::JumpList> blockJumps(code.size());

	auto link = [&] (CCallHelpers::Jump jump, BasicBlock* target) {
	if (blockLabels[target].isSet()) {
	jump.linkTo(blockLabels[target], &jit);
	return;
	}

	blockJumps[target].append(jump);
	};

	PCToOriginMap& pcToOriginMap = code.proc().pcToOriginMap();
	auto addItem = [&] (Inst& inst) {
	if (!inst.origin) {
	pcToOriginMap.appendItem(jit.label(), Origin());
	return;
	}
	pcToOriginMap.appendItem(jit.label(), inst.origin->origin());
	};

	for (BasicBlock* block : code) {
	blockJumps[block].link(&jit);
	blockLabels[block] = jit.label();
	ASSERT(block->size() >= 1);
	for (unsigned i = 0; i < block->size() - 1; ++i) {
	Inst& inst = block->at(i);
	addItem(inst);
	CCallHelpers::Jump jump = inst.generate(jit, context);
	ASSERT_UNUSED(jump, !jump.isSet());
	}

	if (block->last().opcode == Jump
	&& block->successorBlock(0) == code.findNextBlock(block))
	continue;

	addItem(block->last());

	if (isReturn(block->last().opcode)) {
	// We currently don't represent the full prologue/epilogue in Air, so we need to
	// have this override.
	if (code.frameSize()) {
	for (const RegisterAtOffset& entry : code.calleeSaveRegisters()) {
	if (entry.reg().isGPR())
	jit.loadPtr(argFor(entry), entry.reg().gpr());
	else
	jit.loadDouble(argFor(entry), entry.reg().fpr());
	}
	jit.emitFunctionEpilogue();
	} else
	jit.emitFunctionEpilogueWithEmptyFrame();
	jit.ret();
	addItem(block->last());
	continue;
	}

	CCallHelpers::Jump jump = block->last().generate(jit, context);
	switch (block->numSuccessors()) {
	case 0:
	ASSERT(!jump.isSet());
	break;
	case 1:
	link(jump, block->successorBlock(0));
	break;
	case 2:
	link(jump, block->successorBlock(0));
	if (block->successorBlock(1) != code.findNextBlock(block))
	link(jit.jump(), block->successorBlock(1));
	break;
	default:
	RELEASE_ASSERT_NOT_REACHED();
	break;
	}
	addItem(block->last());
	}

	pcToOriginMap.appendItem(jit.label(), Origin());
	// FIXME: Make late paths have Origins: https://bugs.webkit.org/show_bug.cgi?id=153689
	for (auto& latePath : context.latePaths)
	latePath->run(jit, context);
	pcToOriginMap.appendItem(jit.label(), Origin());
	}

	} } } // namespace JSC::B3::Air

	#endif // ENABLE(B3_JIT)