mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-10-19 11:02:59 +02:00
ae65e281f3
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
371 lines
15 KiB
C++
371 lines
15 KiB
C++
//===- MCCodePadder.cpp - Target MC Code Padder ---------------------------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/MC/MCAsmLayout.h"
|
|
#include "llvm/MC/MCCodePadder.h"
|
|
#include "llvm/MC/MCObjectStreamer.h"
|
|
#include <algorithm>
|
|
#include <limits>
|
|
#include <numeric>
|
|
|
|
using namespace llvm;
|
|
|
|
//---------------------------------------------------------------------------
|
|
// MCCodePadder
|
|
//
|
|
|
|
MCCodePadder::~MCCodePadder() {
|
|
for (auto *Policy : CodePaddingPolicies)
|
|
delete Policy;
|
|
}
|
|
|
|
bool MCCodePadder::addPolicy(MCCodePaddingPolicy *Policy) {
|
|
assert(Policy && "Policy must be valid");
|
|
return CodePaddingPolicies.insert(Policy).second;
|
|
}
|
|
|
|
void MCCodePadder::handleBasicBlockStart(MCObjectStreamer *OS,
|
|
const MCCodePaddingContext &Context) {
|
|
assert(OS != nullptr && "OS must be valid");
|
|
assert(this->OS == nullptr && "Still handling another basic block");
|
|
this->OS = OS;
|
|
|
|
ArePoliciesActive = usePoliciesForBasicBlock(Context);
|
|
|
|
bool InsertionPoint = basicBlockRequiresInsertionPoint(Context);
|
|
assert((!InsertionPoint ||
|
|
OS->getCurrentFragment()->getKind() != MCFragment::FT_Align) &&
|
|
"Cannot insert padding nops right after an alignment fragment as it "
|
|
"will ruin the alignment");
|
|
|
|
uint64_t PoliciesMask = MCPaddingFragment::PFK_None;
|
|
if (ArePoliciesActive) {
|
|
PoliciesMask = std::accumulate(
|
|
CodePaddingPolicies.begin(), CodePaddingPolicies.end(),
|
|
MCPaddingFragment::PFK_None,
|
|
[&Context](uint64_t Mask,
|
|
const MCCodePaddingPolicy *Policy) -> uint64_t {
|
|
return Policy->basicBlockRequiresPaddingFragment(Context)
|
|
? (Mask | Policy->getKindMask())
|
|
: Mask;
|
|
});
|
|
}
|
|
|
|
if (InsertionPoint || PoliciesMask != MCPaddingFragment::PFK_None) {
|
|
MCPaddingFragment *PaddingFragment = OS->getOrCreatePaddingFragment();
|
|
if (InsertionPoint)
|
|
PaddingFragment->setAsInsertionPoint();
|
|
PaddingFragment->setPaddingPoliciesMask(
|
|
PaddingFragment->getPaddingPoliciesMask() | PoliciesMask);
|
|
}
|
|
}
|
|
|
|
void MCCodePadder::handleBasicBlockEnd(const MCCodePaddingContext &Context) {
|
|
assert(this->OS != nullptr && "Not handling a basic block");
|
|
OS = nullptr;
|
|
}
|
|
|
|
void MCCodePadder::handleInstructionBegin(const MCInst &Inst) {
|
|
if (!OS)
|
|
return; // instruction was emitted outside a function
|
|
|
|
assert(CurrHandledInstFragment == nullptr && "Can't start handling an "
|
|
"instruction while still "
|
|
"handling another instruction");
|
|
|
|
bool InsertionPoint = instructionRequiresInsertionPoint(Inst);
|
|
assert((!InsertionPoint ||
|
|
OS->getCurrentFragment()->getKind() != MCFragment::FT_Align) &&
|
|
"Cannot insert padding nops right after an alignment fragment as it "
|
|
"will ruin the alignment");
|
|
|
|
uint64_t PoliciesMask = MCPaddingFragment::PFK_None;
|
|
if (ArePoliciesActive) {
|
|
PoliciesMask = std::accumulate(
|
|
CodePaddingPolicies.begin(), CodePaddingPolicies.end(),
|
|
MCPaddingFragment::PFK_None,
|
|
[&Inst](uint64_t Mask, const MCCodePaddingPolicy *Policy) -> uint64_t {
|
|
return Policy->instructionRequiresPaddingFragment(Inst)
|
|
? (Mask | Policy->getKindMask())
|
|
: Mask;
|
|
});
|
|
}
|
|
MCFragment *CurrFragment = OS->getCurrentFragment();
|
|
// CurrFragment can be a previously created MCPaddingFragment. If so, let's
|
|
// update it with the information we have, such as the instruction that it
|
|
// should point to.
|
|
bool needToUpdateCurrFragment =
|
|
CurrFragment != nullptr &&
|
|
CurrFragment->getKind() == MCFragment::FT_Padding;
|
|
if (InsertionPoint || PoliciesMask != MCPaddingFragment::PFK_None ||
|
|
needToUpdateCurrFragment) {
|
|
// temporarily holding the fragment as CurrHandledInstFragment, to be
|
|
// updated after the instruction will be written
|
|
CurrHandledInstFragment = OS->getOrCreatePaddingFragment();
|
|
if (InsertionPoint)
|
|
CurrHandledInstFragment->setAsInsertionPoint();
|
|
CurrHandledInstFragment->setPaddingPoliciesMask(
|
|
CurrHandledInstFragment->getPaddingPoliciesMask() | PoliciesMask);
|
|
}
|
|
}
|
|
|
|
void MCCodePadder::handleInstructionEnd(const MCInst &Inst) {
|
|
if (!OS)
|
|
return; // instruction was emitted outside a function
|
|
if (CurrHandledInstFragment == nullptr)
|
|
return;
|
|
|
|
MCFragment *InstFragment = OS->getCurrentFragment();
|
|
if (MCDataFragment *InstDataFragment =
|
|
dyn_cast_or_null<MCDataFragment>(InstFragment))
|
|
// Inst is a fixed size instruction and was encoded into a MCDataFragment.
|
|
// Let the fragment hold it and its size. Its size is the current size of
|
|
// the data fragment, as the padding fragment was inserted right before it
|
|
// and nothing was written yet except Inst
|
|
CurrHandledInstFragment->setInstAndInstSize(
|
|
Inst, InstDataFragment->getContents().size());
|
|
else if (MCRelaxableFragment *InstRelaxableFragment =
|
|
dyn_cast_or_null<MCRelaxableFragment>(InstFragment))
|
|
// Inst may be relaxed and its size may vary.
|
|
// Let the fragment hold the instruction and the MCRelaxableFragment
|
|
// that's holding it.
|
|
CurrHandledInstFragment->setInstAndInstFragment(Inst,
|
|
InstRelaxableFragment);
|
|
else
|
|
llvm_unreachable("After encoding an instruction current fragment must be "
|
|
"either a MCDataFragment or a MCRelaxableFragment");
|
|
|
|
CurrHandledInstFragment = nullptr;
|
|
}
|
|
|
|
MCPFRange &MCCodePadder::getJurisdiction(MCPaddingFragment *Fragment,
|
|
MCAsmLayout &Layout) {
|
|
auto JurisdictionLocation = FragmentToJurisdiction.find(Fragment);
|
|
if (JurisdictionLocation != FragmentToJurisdiction.end())
|
|
return JurisdictionLocation->second;
|
|
|
|
MCPFRange Jurisdiction;
|
|
|
|
// Forward scanning the fragments in this section, starting from the given
|
|
// fragments, and adding relevant MCPaddingFragments to the Jurisdiction
|
|
for (MCFragment *CurrFragment = Fragment; CurrFragment != nullptr;
|
|
CurrFragment = CurrFragment->getNextNode()) {
|
|
|
|
MCPaddingFragment *CurrPaddingFragment =
|
|
dyn_cast<MCPaddingFragment>(CurrFragment);
|
|
if (CurrPaddingFragment == nullptr)
|
|
continue;
|
|
|
|
if (CurrPaddingFragment != Fragment &&
|
|
CurrPaddingFragment->isInsertionPoint())
|
|
// Found next insertion point Fragment. From now on it's its jurisdiction.
|
|
break;
|
|
for (const auto *Policy : CodePaddingPolicies) {
|
|
if (CurrPaddingFragment->hasPaddingPolicy(Policy->getKindMask())) {
|
|
Jurisdiction.push_back(CurrPaddingFragment);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
auto InsertionResult =
|
|
FragmentToJurisdiction.insert(std::make_pair(Fragment, Jurisdiction));
|
|
assert(InsertionResult.second &&
|
|
"Insertion to FragmentToJurisdiction failed");
|
|
return InsertionResult.first->second;
|
|
}
|
|
|
|
uint64_t MCCodePadder::getMaxWindowSize(MCPaddingFragment *Fragment,
|
|
MCAsmLayout &Layout) {
|
|
auto MaxFragmentSizeLocation = FragmentToMaxWindowSize.find(Fragment);
|
|
if (MaxFragmentSizeLocation != FragmentToMaxWindowSize.end())
|
|
return MaxFragmentSizeLocation->second;
|
|
|
|
MCPFRange &Jurisdiction = getJurisdiction(Fragment, Layout);
|
|
uint64_t JurisdictionMask = MCPaddingFragment::PFK_None;
|
|
for (const auto *Protege : Jurisdiction)
|
|
JurisdictionMask |= Protege->getPaddingPoliciesMask();
|
|
|
|
uint64_t MaxFragmentSize = UINT64_C(0);
|
|
for (const auto *Policy : CodePaddingPolicies)
|
|
if ((JurisdictionMask & Policy->getKindMask()) !=
|
|
MCPaddingFragment::PFK_None)
|
|
MaxFragmentSize = std::max(MaxFragmentSize, Policy->getWindowSize());
|
|
|
|
auto InsertionResult =
|
|
FragmentToMaxWindowSize.insert(std::make_pair(Fragment, MaxFragmentSize));
|
|
assert(InsertionResult.second &&
|
|
"Insertion to FragmentToMaxWindowSize failed");
|
|
return InsertionResult.first->second;
|
|
}
|
|
|
|
bool MCCodePadder::relaxFragment(MCPaddingFragment *Fragment,
|
|
MCAsmLayout &Layout) {
|
|
if (!Fragment->isInsertionPoint())
|
|
return false;
|
|
uint64_t OldSize = Fragment->getSize();
|
|
|
|
uint64_t MaxWindowSize = getMaxWindowSize(Fragment, Layout);
|
|
if (MaxWindowSize == UINT64_C(0))
|
|
return false;
|
|
assert(isPowerOf2_64(MaxWindowSize) &&
|
|
"MaxWindowSize must be an integer power of 2");
|
|
uint64_t SectionAlignment = Fragment->getParent()->getAlignment();
|
|
assert(isPowerOf2_64(SectionAlignment) &&
|
|
"SectionAlignment must be an integer power of 2");
|
|
|
|
MCPFRange &Jurisdiction = getJurisdiction(Fragment, Layout);
|
|
uint64_t OptimalSize = UINT64_C(0);
|
|
double OptimalWeight = std::numeric_limits<double>::max();
|
|
uint64_t MaxFragmentSize = MaxWindowSize - UINT16_C(1);
|
|
for (uint64_t Size = UINT64_C(0); Size <= MaxFragmentSize; ++Size) {
|
|
Fragment->setSize(Size);
|
|
Layout.invalidateFragmentsFrom(Fragment);
|
|
double SizeWeight = 0.0;
|
|
// The section is guaranteed to be aligned to SectionAlignment, but that
|
|
// doesn't guarantee the exact section offset w.r.t. the policies window
|
|
// size.
|
|
// As a concrete example, the section could be aligned to 16B, but a
|
|
// policy's window size can be 32B. That means that the section actual start
|
|
// address can either be 0mod32 or 16mod32. The said policy will act
|
|
// differently for each case, so we need to take both into consideration.
|
|
for (uint64_t Offset = UINT64_C(0); Offset < MaxWindowSize;
|
|
Offset += SectionAlignment) {
|
|
double OffsetWeight = std::accumulate(
|
|
CodePaddingPolicies.begin(), CodePaddingPolicies.end(), 0.0,
|
|
[&Jurisdiction, &Offset, &Layout](
|
|
double Weight, const MCCodePaddingPolicy *Policy) -> double {
|
|
double PolicyWeight =
|
|
Policy->computeRangePenaltyWeight(Jurisdiction, Offset, Layout);
|
|
assert(PolicyWeight >= 0.0 && "A penalty weight must be positive");
|
|
return Weight + PolicyWeight;
|
|
});
|
|
SizeWeight = std::max(SizeWeight, OffsetWeight);
|
|
}
|
|
if (SizeWeight < OptimalWeight) {
|
|
OptimalWeight = SizeWeight;
|
|
OptimalSize = Size;
|
|
}
|
|
if (OptimalWeight == 0.0)
|
|
break;
|
|
}
|
|
|
|
Fragment->setSize(OptimalSize);
|
|
Layout.invalidateFragmentsFrom(Fragment);
|
|
return OldSize != OptimalSize;
|
|
}
|
|
|
|
//---------------------------------------------------------------------------
|
|
// MCCodePaddingPolicy
|
|
//
|
|
|
|
uint64_t MCCodePaddingPolicy::getNextFragmentOffset(const MCFragment *Fragment,
|
|
const MCAsmLayout &Layout) {
|
|
assert(Fragment != nullptr && "Fragment cannot be null");
|
|
MCFragment const *NextFragment = Fragment->getNextNode();
|
|
return NextFragment == nullptr
|
|
? Layout.getSectionAddressSize(Fragment->getParent())
|
|
: Layout.getFragmentOffset(NextFragment);
|
|
}
|
|
|
|
uint64_t
|
|
MCCodePaddingPolicy::getFragmentInstByte(const MCPaddingFragment *Fragment,
|
|
MCAsmLayout &Layout) const {
|
|
uint64_t InstByte = getNextFragmentOffset(Fragment, Layout);
|
|
if (InstByteIsLastByte)
|
|
InstByte += Fragment->getInstSize() - UINT64_C(1);
|
|
return InstByte;
|
|
}
|
|
|
|
uint64_t
|
|
MCCodePaddingPolicy::computeWindowEndAddress(const MCPaddingFragment *Fragment,
|
|
uint64_t Offset,
|
|
MCAsmLayout &Layout) const {
|
|
uint64_t InstByte = getFragmentInstByte(Fragment, Layout);
|
|
return alignTo(InstByte + UINT64_C(1) + Offset, WindowSize) - Offset;
|
|
}
|
|
|
|
double MCCodePaddingPolicy::computeRangePenaltyWeight(
|
|
const MCPFRange &Range, uint64_t Offset, MCAsmLayout &Layout) const {
|
|
|
|
SmallVector<MCPFRange, 8> Windows;
|
|
SmallVector<MCPFRange, 8>::iterator CurrWindowLocation = Windows.end();
|
|
for (const MCPaddingFragment *Fragment : Range) {
|
|
if (!Fragment->hasPaddingPolicy(getKindMask()))
|
|
continue;
|
|
uint64_t FragmentWindowEndAddress =
|
|
computeWindowEndAddress(Fragment, Offset, Layout);
|
|
if (CurrWindowLocation == Windows.end() ||
|
|
FragmentWindowEndAddress !=
|
|
computeWindowEndAddress(*CurrWindowLocation->begin(), Offset,
|
|
Layout)) {
|
|
// next window is starting
|
|
Windows.push_back(MCPFRange());
|
|
CurrWindowLocation = Windows.end() - 1;
|
|
}
|
|
CurrWindowLocation->push_back(Fragment);
|
|
}
|
|
|
|
if (Windows.empty())
|
|
return 0.0;
|
|
|
|
double RangeWeight = 0.0;
|
|
SmallVector<MCPFRange, 8>::iterator I = Windows.begin();
|
|
RangeWeight += computeFirstWindowPenaltyWeight(*I, Offset, Layout);
|
|
++I;
|
|
RangeWeight += std::accumulate(
|
|
I, Windows.end(), 0.0,
|
|
[this, &Layout, &Offset](double Weight, MCPFRange &Window) -> double {
|
|
return Weight += computeWindowPenaltyWeight(Window, Offset, Layout);
|
|
});
|
|
return RangeWeight;
|
|
}
|
|
|
|
double MCCodePaddingPolicy::computeFirstWindowPenaltyWeight(
|
|
const MCPFRange &Window, uint64_t Offset, MCAsmLayout &Layout) const {
|
|
if (Window.empty())
|
|
return 0.0;
|
|
uint64_t WindowEndAddress =
|
|
computeWindowEndAddress(*Window.begin(), Offset, Layout);
|
|
|
|
MCPFRange FullWindowFirstPart; // will hold all the fragments that are in the
|
|
// same window as the fragments in the given
|
|
// window but their penalty weight should not
|
|
// be added
|
|
for (const MCFragment *Fragment = (*Window.begin())->getPrevNode();
|
|
Fragment != nullptr; Fragment = Fragment->getPrevNode()) {
|
|
const MCPaddingFragment *PaddingNopFragment =
|
|
dyn_cast<MCPaddingFragment>(Fragment);
|
|
if (PaddingNopFragment == nullptr ||
|
|
!PaddingNopFragment->hasPaddingPolicy(getKindMask()))
|
|
continue;
|
|
if (WindowEndAddress !=
|
|
computeWindowEndAddress(PaddingNopFragment, Offset, Layout))
|
|
break;
|
|
|
|
FullWindowFirstPart.push_back(PaddingNopFragment);
|
|
}
|
|
|
|
std::reverse(FullWindowFirstPart.begin(), FullWindowFirstPart.end());
|
|
double FullWindowFirstPartWeight =
|
|
computeWindowPenaltyWeight(FullWindowFirstPart, Offset, Layout);
|
|
|
|
MCPFRange FullWindow(
|
|
FullWindowFirstPart); // will hold all the fragments that are in the
|
|
// same window as the fragments in the given
|
|
// window, whether their weight should be added
|
|
// or not
|
|
FullWindow.append(Window.begin(), Window.end());
|
|
double FullWindowWeight =
|
|
computeWindowPenaltyWeight(FullWindow, Offset, Layout);
|
|
|
|
assert(FullWindowWeight >= FullWindowFirstPartWeight &&
|
|
"More fragments necessarily means bigger weight");
|
|
return FullWindowWeight - FullWindowFirstPartWeight;
|
|
}
|