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AirGenerate.cpp
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339 lines (274 loc) · 12.5 KB
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/*
* Copyright (C) 2015-2020 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 "AirAllocateRegistersAndStackAndGenerateCode.h"
#include "AirAllocateRegistersAndStackByLinearScan.h"
#include "AirAllocateRegistersByGraphColoring.h"
#include "AirAllocateStackByGraphColoring.h"
#include "AirCode.h"
#include "AirEliminateDeadCode.h"
#include "AirFixObviousSpills.h"
#include "AirFixPartialRegisterStalls.h"
#include "AirGenerationContext.h"
#include "AirLogRegisterPressure.h"
#include "AirLowerAfterRegAlloc.h"
#include "AirLowerEntrySwitch.h"
#include "AirLowerMacros.h"
#include "AirLowerStackArgs.h"
#include "AirOpcodeUtils.h"
#include "AirOptimizeBlockOrder.h"
#include "AirReportUsedRegisters.h"
#include "AirSimplifyCFG.h"
#include "AirValidate.h"
#include "B3Common.h"
#include "B3Procedure.h"
#include "B3TimingScope.h"
#include "CCallHelpers.h"
#include "DisallowMacroScratchRegisterUsage.h"
#include <wtf/IndexMap.h>
namespace JSC { namespace B3 { namespace Air {
void prepareForGeneration(Code& code)
{
TimingScope timingScope("Air::prepareForGeneration");
// If we're doing super verbose dumping, the phase scope of any phase will already do a dump.
if (shouldDumpIR(AirMode) && !shouldDumpIRAtEachPhase(AirMode)) {
dataLog(tierName, "Initial air:\n");
dataLog(code);
}
// We don't expect the incoming code to have predecessors computed.
code.resetReachability();
if (shouldValidateIR())
validate(code);
if (!code.optLevel()) {
lowerMacros(code);
// FIXME: The name of this phase doesn't make much sense in O0 since we do this before
// register allocation.
lowerAfterRegAlloc(code);
// Actually create entrypoints.
lowerEntrySwitch(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);
if (shouldValidateIR())
validate(code);
if (shouldDumpIR(AirMode)) {
dataLog("Air after ", code.lastPhaseName(), ", before generation:\n");
dataLog(code);
}
code.m_generateAndAllocateRegisters = makeUnique<GenerateAndAllocateRegisters>(code);
code.m_generateAndAllocateRegisters->prepareForGeneration();
return;
}
simplifyCFG(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);
size_t numTmps = code.numTmps(Bank::GP) + code.numTmps(Bank::FP);
if (code.optLevel() == 1 || numTmps > Options::maximumTmpsForGraphColoring()) {
// When we're compiling quickly, we do register and stack allocation in one linear scan
// phase. It's fast because it computes liveness only once.
allocateRegistersAndStackByLinearScan(code);
if (Options::logAirRegisterPressure()) {
dataLog("Register pressure after register allocation:\n");
logRegisterPressure(code);
}
// We may still need to do post-allocation lowering. Doing it after both register and
// stack allocation is less optimal, but it works fine.
lowerAfterRegAlloc(code);
} else {
// NOTE: B3 -O2 generates code that runs 1.5x-2x faster than code generated by -O1.
// Most of this performance benefit is from -O2's graph coloring register allocation
// and stack allocation pipeline, which you see below.
// Register allocation for all the Tmps that do not have a corresponding machine
// register. After this phase, every Tmp has a reg.
allocateRegistersByGraphColoring(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);
// This does first-fit allocation of stack slots using an interference graph plus a
// bunch of other optimizations.
allocateStackByGraphColoring(code);
}
// This turns all Stack and CallArg Args into Addr args that use the frame pointer.
lowerStackArgs(code);
// If we coalesced moves then we can unbreak critical edges. This is the main reason for this
// phase.
simplifyCFG(code);
// This is needed to satisfy a requirement of B3::StackmapValue. This also removes dead
// code. We can avoid running this when certain optimizations are disabled.
if (code.optLevel() >= 2 || code.needsUsedRegisters())
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);
// Actually create entrypoints.
lowerEntrySwitch(code);
// The control flow graph can be simplified further after we have lowered EntrySwitch.
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);
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);
}
}
static void generateWithAlreadyAllocatedRegisters(Code& code, CCallHelpers& jit)
{
TimingScope timingScope("Air::generate");
DisallowMacroScratchRegisterUsage disallowScratch(jit);
// And now, we generate code.
GenerationContext context;
context.code = &code;
context.blockLabels.resize(code.size());
for (BasicBlock* block : code)
context.blockLabels[block] = Box<CCallHelpers::Label>::create();
IndexMap<BasicBlock*, CCallHelpers::JumpList> blockJumps(code.size());
auto link = [&] (CCallHelpers::Jump jump, BasicBlock* target) {
if (context.blockLabels[target]->isSet()) {
jump.linkTo(*context.blockLabels[target], &jit);
return;
}
blockJumps[target].append(jump);
};
PCToOriginMap& pcToOriginMap = code.proc().pcToOriginMap();
auto addItem = [&] (Inst& inst) {
if (!inst.origin) {
pcToOriginMap.appendItem(jit.labelIgnoringWatchpoints(), Origin());
return;
}
pcToOriginMap.appendItem(jit.labelIgnoringWatchpoints(), inst.origin->origin());
};
Disassembler* disassembler = code.disassembler();
for (BasicBlock* block : code) {
context.currentBlock = block;
context.indexInBlock = UINT_MAX;
blockJumps[block].link(&jit);
CCallHelpers::Label label = jit.label();
*context.blockLabels[block] = label;
if (disassembler)
disassembler->startBlock(block, jit);
if (Optional<unsigned> entrypointIndex = code.entrypointIndex(block)) {
ASSERT(code.isEntrypoint(block));
if (disassembler)
disassembler->startEntrypoint(jit);
code.prologueGeneratorForEntrypoint(*entrypointIndex)->run(jit, code);
if (disassembler)
disassembler->endEntrypoint(jit);
} else
ASSERT(!code.isEntrypoint(block));
ASSERT(block->size() >= 1);
for (unsigned i = 0; i < block->size() - 1; ++i) {
context.indexInBlock = i;
Inst& inst = block->at(i);
addItem(inst);
auto start = jit.labelIgnoringWatchpoints();
CCallHelpers::Jump jump = inst.generate(jit, context);
ASSERT_UNUSED(jump, !jump.isSet());
auto end = jit.labelIgnoringWatchpoints();
if (disassembler)
disassembler->addInst(&inst, start, end);
}
context.indexInBlock = block->size() - 1;
if (block->last().kind.opcode == Jump
&& block->successorBlock(0) == code.findNextBlock(block))
continue;
addItem(block->last());
if (isReturn(block->last().kind.opcode)) {
// We currently don't represent the full prologue/epilogue in Air, so we need to
// have this override.
auto start = jit.labelIgnoringWatchpoints();
code.emitEpilogue(jit);
addItem(block->last());
auto end = jit.labelIgnoringWatchpoints();
if (disassembler)
disassembler->addInst(&block->last(), start, end);
continue;
}
auto start = jit.labelIgnoringWatchpoints();
CCallHelpers::Jump jump = block->last().generate(jit, context);
auto end = jit.labelIgnoringWatchpoints();
if (disassembler)
disassembler->addInst(&block->last(), start, end);
// The jump won't be set for patchpoints. It won't be set for Oops because then it won't have
// any successors.
if (jump.isSet()) {
switch (block->numSuccessors()) {
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());
}
context.currentBlock = nullptr;
context.indexInBlock = UINT_MAX;
Vector<CCallHelpers::Label> entrypointLabels(code.numEntrypoints());
for (unsigned i = code.numEntrypoints(); i--;)
entrypointLabels[i] = *context.blockLabels[code.entrypoint(i).block()];
code.setEntrypointLabels(WTFMove(entrypointLabels));
pcToOriginMap.appendItem(jit.label(), Origin());
// FIXME: Make late paths have Origins: https://bugs.webkit.org/show_bug.cgi?id=153689
if (disassembler)
disassembler->startLatePath(jit);
for (auto& latePath : context.latePaths)
latePath->run(jit, context);
if (disassembler)
disassembler->endLatePath(jit);
pcToOriginMap.appendItem(jit.labelIgnoringWatchpoints(), Origin());
}
void generate(Code& code, CCallHelpers& jit)
{
if (code.optLevel())
generateWithAlreadyAllocatedRegisters(code, jit);
else
code.m_generateAndAllocateRegisters->generate(jit);
}
} } } // namespace JSC::B3::Air
#endif // ENABLE(B3_JIT)