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/*========================== begin_copyright_notice ============================
Copyright (C) 2017-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
//
/// GenXDeadVectorRemoval
/// ---------------------
///
/// GenXDeadVectorRemoval is an aggressive dead code removal pass that analyzes
/// individual elements of a vector rather than whole values.
///
/// As a result of this analysis, the pass can then make the two following
/// modifications to the code:
///
/// 1. If all vector elements of an instruction result turn out to be unused,
/// the instruction is removed. In fact, this pass just sets all its uses to
/// undef, relying on the subsequent dead code removal pass to actually
/// remove it.
///
/// 2. If all vector elements of the "old value" input (even a constant) of a
/// wrregion turn out to be unused, then that input is set to undef. This
/// covers further cases over (1) above:
///
/// a. the "old value" input is constant, and we want to turn it into undef
/// to save a useless constant load;
///
/// b. the "old value" input is an instruction that does have elements used
/// elsewhere, and we want to turn it into undef to detach the two webs
/// of defs and uses from each other to reduce register pressure in
/// between.
///
/// Besides this pass removes all write intrinsics (wrregion, wrpredregion)
/// that have undef input value and replaces their uses with the old value.
//===----------------------------------------------------------------------===//
#include "GenX.h"
#include "GenXBaling.h"
#include "GenXUtil.h"
#include "vc/GenXOpts/GenXAnalysis.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvmWrapper/IR/DerivedTypes.h"
#include <queue>
#include <set>
#include "Probe/Assertion.h"
#define DEBUG_TYPE "GENX_DEAD_VECTOR_REMOVAL"
using namespace llvm;
using namespace genx;
using namespace GenXIntrinsic::GenXRegion;
static cl::opt<unsigned> LimitGenXDeadVectorRemoval("limit-genx-dead-vector-removal", cl::init(UINT_MAX), cl::Hidden,
cl::desc("Limit GenX dead element removal."));
namespace {
// LiveBitsStorage : encapsulate how live bits for a vector value are stored
// For 31/63 elements or fewer, the bitmap is inside the LiveBitsStorage
// object. For 32/64 elements or more, the bitmap is separately allocated.
class LiveBitsStorage {
uintptr_t V;
public:
LiveBitsStorage() : V(0) {}
~LiveBitsStorage() {
if (auto P = getExternal())
delete[] P;
V = 0;
}
private:
// getExternal : get the external pointer, 0 if none
// Whether we have an external pointer is encoded in the top bit.
// The pointer itself is shifted down one and stored in the other bits.
uintptr_t *getExternal() {
if ((intptr_t)V >= 0)
return nullptr; // top bit not set, not external
return (uintptr_t *)(V * 2);
}
// setExternal : set the external pointer
void setExternal(uintptr_t *P) {
IGC_ASSERT(!getExternal());
V = (uintptr_t)P >> 1 | (uintptr_t)1U << (sizeof(uintptr_t) * 8 - 1);
}
public:
// setNumElements : set the number of elements to be stored in this
// LiveBitsStorage. Allocate external storage if necessary.
void setNumElements(unsigned NumElements) {
if (NumElements >= sizeof(uintptr_t) * 8 - 1) {
unsigned Size = NumElements + sizeof(uintptr_t) * 8 - 1
/ (sizeof(uintptr_t) * 8);
setExternal(new uintptr_t[Size]);
memset(getExternal(), 0, Size * sizeof(uintptr_t));
}
}
// get : get the pointer to the bitmap
uintptr_t *get() {
if (auto P = getExternal())
return P;
return &V;
}
};
// LiveBits : encapsulate a pointer to a bitmap of element liveness and its size
class LiveBits {
uintptr_t *P;
unsigned NumElements;
public:
static const unsigned BitsPerWord = sizeof(uintptr_t) * 8;
LiveBits() : P(nullptr), NumElements(0) {}
LiveBits(LiveBitsStorage *LBS, unsigned NumElements)
: P(LBS->get()), NumElements(NumElements) {}
// getNumElements : get the number of elements in this bitmap
unsigned getNumElements() const { return NumElements; }
// get : get a bit value
bool get(unsigned Idx) const {
IGC_ASSERT(Idx < NumElements);
IGC_ASSERT(BitsPerWord);
return P[Idx / BitsPerWord] >> (Idx % BitsPerWord) & 1;
}
// isAllZero : return true if all bits zero
bool isAllZero() const;
// set : set a bit value
// Returns true if value changed
bool set(unsigned Idx, bool Val = true);
// copy : copy all bits from another LiveBits
// Returns true if value changed
bool copy(LiveBits Src);
// orBits : or all bits from another LiveBits into this one
// Returns true if value changed
bool orBits(LiveBits Src);
// setRange : set range of bits, returning true if any changed
bool setRange(unsigned Start, unsigned Len);
// debug print
void print(raw_ostream &OS) const;
};
#ifndef NDEBUG
static raw_ostream &operator<<(raw_ostream &OS, const LiveBits &LB) {
LB.print(OS);
return OS;
}
#endif
// GenXDeadVectorRemoval : dead vector element removal pass
class GenXDeadVectorRemoval : public FunctionPass {
std::map<Instruction *, LiveBitsStorage> InstMap;
std::set<Instruction *> WorkListSet;
std::queue<Instruction *> WorkList;
std::set<Instruction *> WrRegionsWithUsedOldInput;
bool WorkListPhase = false;
unsigned RemovedCount = 0;
public:
static char ID;
explicit GenXDeadVectorRemoval() : FunctionPass(ID) { }
StringRef getPassName() const override {
return "GenX dead vector element removal pass";
}
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnFunction(Function &F) override;
private:
void clear() {
InstMap.clear();
WorkListSet.clear();
IGC_ASSERT(WorkList.empty());
WrRegionsWithUsedOldInput.clear();
WorkListPhase = false;
RemovedCount = 0;
}
bool nullOutInstructions(Function *F);
void processInst(Instruction *Inst);
void processRdRegion(Instruction *Inst, LiveBits LB);
void processWrRegion(Instruction *Inst, LiveBits LB);
void processBitCast(Instruction *Inst, LiveBits LB);
void processElementwise(Instruction *Inst, LiveBits LB);
void markWhollyLive(Value *V);
void addToWorkList(Instruction *Inst);
LiveBits createLiveBits(Instruction *Inst);
LiveBits getLiveBits(Instruction *Inst);
};
} // end anonymous namespace
char GenXDeadVectorRemoval::ID = 0;
namespace llvm { void initializeGenXDeadVectorRemovalPass(PassRegistry &); }
INITIALIZE_PASS_BEGIN(GenXDeadVectorRemoval, "GenXDeadVectorRemoval", "GenXDeadVectorRemoval", false, false)
INITIALIZE_PASS_END(GenXDeadVectorRemoval, "GenXDeadVectorRemoval", "GenXDeadVectorRemoval", false, false)
FunctionPass *llvm::createGenXDeadVectorRemovalPass()
{
initializeGenXDeadVectorRemovalPass(*PassRegistry::getPassRegistry());
return new GenXDeadVectorRemoval();
}
void GenXDeadVectorRemoval::getAnalysisUsage(AnalysisUsage &AU) const
{
AU.setPreservesCFG();
}
/***********************************************************************
* isRootInst : check if this is a "root" instruction, one that we want to
* keep even if unused
*/
static bool isRootInst(Instruction *Inst) {
if (isa<ReturnInst>(Inst) || isa<BranchInst>(Inst) ||
Inst->isTerminator() || Inst->mayHaveSideEffects())
return true;
// Even if the whole region is overwritten by a chain of wrregions, wrregions
// to predefined register must not be optimized as they are extremely
// specific.
if (GenXIntrinsic::isWrRegion(Inst) &&
GenXIntrinsic::isReadPredefReg(
Inst->getOperand(GenXIntrinsic::GenXRegion::OldValueOperandNum)))
return true;
if (auto CI = dyn_cast<CallInst>(Inst))
return !CI->onlyReadsMemory();
return false;
}
/***********************************************************************
* GenXDeadVectorRemoval::runOnFunction : process one function
*/
bool GenXDeadVectorRemoval::runOnFunction(Function &F)
{
// First scan all the code to compute the initial live set
WorkListPhase = false;
for (po_iterator<BasicBlock *> i = po_begin(&F.getEntryBlock()),
e = po_end(&F.getEntryBlock()); i != e; ++i) {
BasicBlock *BB = *i;
for (Instruction *Inst = BB->getTerminator(); Inst;) {
if (isRootInst(Inst))
processInst(Inst);
else if (WorkListSet.count(Inst)) {
if (!isa<PHINode>(Inst))
WorkListSet.erase(Inst);
processInst(Inst);
}
Inst = (Inst == &BB->front()) ? nullptr : Inst->getPrevNode();
}
}
WorkListPhase = true;
// initialize the worklist
for (auto Inst : WorkListSet) {
WorkList.push(Inst);
}
// process until the work list is empty.
LLVM_DEBUG(dbgs() << "GenXDeadVectorRemoval: process work list\n");
while (!WorkList.empty()) {
Instruction *Inst = WorkList.front();
WorkList.pop();
WorkListSet.erase(Inst);
processInst(Inst);
}
// Null out unused instructions so the subsequent dead code removal pass
// removes them.
LLVM_DEBUG(dbgs() << "GenXDeadVectorRemoval: null out instructions\n");
bool Modified = nullOutInstructions(&F);
Modified |= simplifyWritesWithUndefInput(F);
clear();
return Modified;
}
/***********************************************************************
* nullOutInstructions : null out unused instructions so the subsequent dead
* code removal pass removes them
*
* For wrregion, there are two special cases:
* - when no elements in the "new value" input of a wrregion are use,
* then bypass the wrregion with the "old value".
* - when no elements in the "old value" input of a wrregion are used,
* then changes the input to undef.
*/
bool GenXDeadVectorRemoval::nullOutInstructions(Function *F) {
bool Modified = false;
for (auto fi = F->begin(), fe = F->end(); fi != fe; ++fi) {
for (auto bi = fi->begin(), be = fi->end(); bi != be; ++bi) {
Instruction *Inst = &*bi;
// Ignore "root" instructions.
if (isRootInst(Inst))
continue;
// See if the instruction has no used elements. If so, null out its uses.
auto LB = getLiveBits(Inst);
if (LB.isAllZero()) {
if (++RemovedCount > LimitGenXDeadVectorRemoval)
return Modified;
if (LimitGenXDeadVectorRemoval != UINT_MAX)
dbgs() << "-limit-genx-dead-vector-removal " << RemovedCount << "\n";
LLVM_DEBUG(if (!Inst->use_empty())
dbgs() << "nulled out uses of " << *Inst << "\n");
while (!Inst->use_empty()) {
Use *U = &*Inst->use_begin();
*U = UndefValue::get((*U)->getType());
}
Modified = true;
} else if (GenXIntrinsic::isWrRegion(Inst)) {
if (!Inst->use_empty()) {
auto *SI = dyn_cast<StoreInst>(Inst->user_back());
if (SI && genx::isGlobalStore(SI)) {
IGC_ASSERT_MESSAGE(Inst->hasOneUse(),
"Wrregion in gstore bale has more than one use");
continue;
}
}
// Otherwise, for a wrregion, check if it is in the old input used set.
// If not, then no element of the "old value" input is used by this
// instruction (even if it has bits set from other uses), and we can
// undef out the input.
Use *U = &Inst->getOperandUse(GenXIntrinsic::GenXRegion::OldValueOperandNum);
if (WrRegionsWithUsedOldInput.find(Inst)
== WrRegionsWithUsedOldInput.end()) {
if (!isa<UndefValue>(*U)) {
if (++RemovedCount > LimitGenXDeadVectorRemoval)
return Modified;
if (LimitGenXDeadVectorRemoval != UINT_MAX)
dbgs() << "-limit-genx-dead-vector-removal " << RemovedCount
<< "\n";
*U = UndefValue::get((*U)->getType());
LLVM_DEBUG(dbgs() << "null out old value input in " << *Inst << "\n");
Modified = true;
}
}
// when no elements in the "new value" input of a wrregion are use,
// then bypass the wrregion with the "old value".
bool bypass = true;
Region R = makeRegionFromBaleInfo(Inst, BaleInfo());
if (R.Mask || R.Indirect)
bypass = false;
else {
for (unsigned RowIdx = R.getOffsetInElements(), Row = 0,
NumRows = R.NumElements / R.Width;
Row != NumRows && bypass; RowIdx += R.VStride, ++Row) {
for (unsigned Idx = RowIdx, Col = 0; Col != R.Width && bypass;
Idx += R.Stride, ++Col) {
if (Idx < LB.getNumElements() && LB.get(Idx))
bypass = false;
}
}
}
if (bypass) {
Inst->replaceAllUsesWith(Inst->getOperandUse(GenXIntrinsic::GenXRegion::OldValueOperandNum));
Modified = true;
}
}
}
}
return Modified;
}
/***********************************************************************
* processInst : process an instruction in the dead element removal pass
*/
void GenXDeadVectorRemoval::processInst(Instruction *Inst)
{
LLVM_DEBUG(dbgs() << " " << *Inst << "\n has bits " << getLiveBits(Inst) << "\n");
if (isRootInst(Inst)) {
// This is a "root" instruction. Mark its inputs as wholly live.
for (unsigned oi = 0, oe = Inst->getNumOperands(); oi != oe; ++oi)
markWhollyLive(Inst->getOperand(oi));
return;
}
// Check for the result of the instruction not being used at all.
auto LB = getLiveBits(Inst);
if (!LB.getNumElements())
return;
// Handle phi node.
if (auto Phi = dyn_cast<PHINode>(Inst)) {
processElementwise(Phi, LB);
return;
}
// Special case for bitcast.
if (auto BC = dyn_cast<BitCastInst>(Inst)) {
processBitCast(BC, LB);
return;
}
// Check for element-wise instructions.
if (isa<BinaryOperator>(Inst) || isa<CastInst>(Inst)
|| isa<SelectInst>(Inst) || isa<CmpInst>(Inst)) {
processElementwise(Inst, LB);
return;
}
// Check for rdregion and wrregion.
switch (GenXIntrinsic::getGenXIntrinsicID(Inst)) {
case GenXIntrinsic::genx_rdregionf:
case GenXIntrinsic::genx_rdregioni:
case GenXIntrinsic::genx_rdpredregion:
processRdRegion(Inst, LB);
return;
case GenXIntrinsic::genx_wrregionf:
case GenXIntrinsic::genx_wrregioni:
case GenXIntrinsic::genx_wrconstregion:
case GenXIntrinsic::genx_wrpredregion:
processWrRegion(Inst, LB);
return;
default:
break;
}
// For any other instruction, just mark all operands as wholly live.
for (unsigned oi = 0, oe = Inst->getNumOperands(); oi != oe; ++oi)
markWhollyLive(Inst->getOperand(oi));
}
/***********************************************************************
* processRdRegion : process a rdregion instruction for element liveness
*/
void GenXDeadVectorRemoval::processRdRegion(Instruction *Inst, LiveBits LB)
{
auto InInst = dyn_cast<Instruction>(
Inst->getOperand(GenXIntrinsic::GenXRegion::OldValueOperandNum));
Region R = makeRegionFromBaleInfo(Inst, BaleInfo());
if (R.Indirect) {
markWhollyLive(InInst);
markWhollyLive(Inst->getOperand(GenXIntrinsic::GenXRegion::RdIndexOperandNum));
return;
}
if (!InInst)
return;
// Set bits in InLB (InInst's livebits) for live elements read by the
// rdregion.
bool Modified = false;
LiveBits InLB = createLiveBits(InInst);
for (unsigned RowIdx = R.getOffsetInElements(), Row = 0,
NumRows = R.NumElements / R.Width;
Row != NumRows; RowIdx += R.VStride, ++Row)
for (unsigned Idx = RowIdx, Col = 0; Col != R.Width; Idx += R.Stride, ++Col)
if (LB.get(Row * R.Width + Col))
if (Idx < InLB.getNumElements())
Modified |= InLB.set(Idx);
if (Modified)
addToWorkList(InInst);
}
static Constant *undefDeadConstElements(Constant *C, LiveBits LB) {
if (isa<UndefValue>(C) || isa<ConstantAggregateZero>(C))
return C;
if (!C->getType()->isVectorTy()) {
IGC_ASSERT(LB.getNumElements() == 1);
return LB.get(0) ? C : UndefValue::get(C->getType());
}
SmallVector<Constant *, 8> NewElems;
for (unsigned i = 0; i < LB.getNumElements(); ++i)
NewElems.push_back(LB.get(i)
? C->getAggregateElement(i)
: UndefValue::get(C->getType()->getScalarType()));
return ConstantVector::get(NewElems);
}
/***********************************************************************
* processWrRegion : process a wrregion instruction for element liveness
*/
void GenXDeadVectorRemoval::processWrRegion(Instruction *Inst, LiveBits LB)
{
Region R = makeRegionFromBaleInfo(Inst, BaleInfo());
if (R.Mask)
markWhollyLive(Inst->getOperand(GenXIntrinsic::GenXRegion::PredicateOperandNum));
auto NewInInst = dyn_cast<Instruction>(
Inst->getOperand(GenXIntrinsic::GenXRegion::NewValueOperandNum));
if (R.Indirect) {
markWhollyLive(NewInInst);
markWhollyLive(Inst->getOperand(GenXIntrinsic::GenXRegion::WrIndexOperandNum));
} else if (NewInInst) {
// Set bits in NewInLB (NewInInst's livebits) for live elements read by
// the wrregion in the "new value" input.
bool Modified = false;
LiveBits NewInLB = createLiveBits(NewInInst);
for (unsigned RowIdx = R.getOffsetInElements(), Row = 0,
NumRows = R.NumElements / R.Width;
Row != NumRows; RowIdx += R.VStride, ++Row)
for (unsigned Idx = RowIdx, Col = 0; Col != R.Width;
Idx += R.Stride, ++Col)
if (Idx < LB.getNumElements() && LB.get(Idx))
Modified |= NewInLB.set(Row * R.Width + Col);
if (Modified)
addToWorkList(NewInInst);
}
// For the "old value" input, we want to see if any elements are used even if
// the input is a constant, since we want to be able to turn it into undef
// later on if it is not used. In the non-instruction case, OldInLB is left
// in a state where it contains no bits and OldInLB.getNumElements() is 0.
LiveBits OldInLB;
LiveBitsStorage ConstVecLBS;
auto OldInVal = Inst->getOperand(GenXIntrinsic::GenXRegion::OldValueOperandNum);
if (auto OldInInst = dyn_cast<Instruction>(OldInVal))
OldInLB = createLiveBits(OldInInst);
else if (auto OldInConst = dyn_cast<Constant>(OldInVal)) {
ConstVecLBS.setNumElements(LB.getNumElements());
OldInLB = LiveBits(&ConstVecLBS, LB.getNumElements());
}
bool Modified = false;
bool UsedOldInput = false;
if (R.Indirect) {
if (OldInLB.getNumElements())
Modified = OldInLB.orBits(LB);
UsedOldInput = true;
} else {
// Set bits in OldLB (OldInInst's livebits) for live elements read by the
// wrregion in the "old value" input, excluding ones that come from the
// "new value" input.
unsigned NextRow = 0, NextCol = 0, NextIdx = R.getOffsetInElements(),
NextRowIdx = NextIdx, NumRows = R.NumElements / R.Width;
for (unsigned Idx = 0, End = LB.getNumElements(); Idx != End; ++Idx) {
if (Idx == NextIdx) {
// This element comes from the "new value" input, unless the wrregion
// is predicated in which case it could come from either.
if (R.Mask && LB.get(Idx)) {
UsedOldInput = true;
if (OldInLB.getNumElements())
Modified |= OldInLB.set(Idx);
}
if (++NextCol == R.Width) {
if (++NextRow == NumRows)
NextIdx = End;
else
NextIdx = NextRowIdx += R.VStride;
NextCol = 0;
} else
NextIdx += R.Stride;
} else {
// This element comes from the "old value" input.
if (LB.get(Idx)) {
UsedOldInput = true;
if (OldInLB.getNumElements())
Modified |= OldInLB.set(Idx);
}
}
}
}
if (Modified) {
if (auto OldInInst = dyn_cast<Instruction>(OldInVal))
addToWorkList(OldInInst);
// If some constant values are not in use, set it to undef so ConstantLoader
// can benefit from it.
else if (auto OldInConst = dyn_cast<Constant>(OldInVal))
Inst->setOperand(GenXIntrinsic::GenXRegion::OldValueOperandNum,
undefDeadConstElements(OldInConst, OldInLB));
}
if (UsedOldInput) {
// We know that at least one element of the "old value" input is used,
// so add the wrregion to the used old input set.
WrRegionsWithUsedOldInput.insert(Inst);
}
}
/***********************************************************************
* processBitCast : process a bitcast instruction for element liveness
*/
void GenXDeadVectorRemoval::processBitCast(Instruction *Inst, LiveBits LB)
{
LiveBits InLB;
LiveBitsStorage ConstVecLBS;
auto InVal = Inst->getOperand(0);
if (auto InInst = dyn_cast<Instruction>(InVal))
InLB = createLiveBits(InInst);
else if (isa<Constant>(InVal)) {
auto *VTy = dyn_cast<IGCLLVM::FixedVectorType>(InVal->getType());
unsigned NumElems = VTy ? VTy->getNumElements() : 1;
ConstVecLBS.setNumElements(NumElems);
InLB = LiveBits(&ConstVecLBS, NumElems);
} else
return;
bool Modified = false;
if (InLB.getNumElements() == LB.getNumElements())
Modified = InLB.orBits(LB);
else if (InLB.getNumElements() > LB.getNumElements()) {
IGC_ASSERT(LB.getNumElements());
IGC_ASSERT((InLB.getNumElements() % LB.getNumElements()) == 0);
int Scale = InLB.getNumElements() / LB.getNumElements();
// Input element is smaller than result element.
for (unsigned Idx = 0, End = LB.getNumElements(); Idx != End; ++Idx)
if (LB.get(Idx))
Modified |= InLB.setRange(Idx * Scale, Scale);
} else {
IGC_ASSERT(InLB.getNumElements());
IGC_ASSERT((LB.getNumElements() % InLB.getNumElements()) == 0);
int Scale = LB.getNumElements() / InLB.getNumElements();
// Input element is bigger than result element.
for (unsigned Idx = 0, End = InLB.getNumElements(); Idx != End; ++Idx) {
bool IsSet = false;
for (unsigned Idx2 = 0; Idx2 != Scale; ++Idx2)
IsSet |= LB.get(Idx*Scale | Idx2);
if (IsSet)
Modified |= InLB.set(Idx);
}
}
if (Modified) {
if (auto InInst = dyn_cast<Instruction>(InVal))
addToWorkList(InInst);
else if (auto InConst = dyn_cast<Constant>(InVal))
Inst->setOperand(0, undefDeadConstElements(InConst, InLB));
}
}
/***********************************************************************
* processElementwise : process an element-wise instruction such as add or
* a phi node
*/
void GenXDeadVectorRemoval::processElementwise(Instruction *Inst, LiveBits LB)
{
for (unsigned oi = 0, oe = Inst->getNumOperands(); oi != oe; ++oi) {
auto OpndInst = dyn_cast<Instruction>(Inst->getOperand(oi));
if (!OpndInst)
continue;
auto OpndLB = createLiveBits(OpndInst);
if (isa<SelectInst>(Inst) && oi == 0 &&
!OpndInst->getType()->isVectorTy()) {
// First operand of select inst can be scalar, ignore it
markWhollyLive(OpndInst);
continue;
}
if (OpndLB.orBits(LB))
addToWorkList(OpndInst);
}
}
/***********************************************************************
* markWhollyLive : mark a value as wholly live (all elements live)
*/
void GenXDeadVectorRemoval::markWhollyLive(Value *V)
{
auto Inst = dyn_cast_or_null<Instruction>(V);
if (!Inst)
return;
auto LB = createLiveBits(Inst);
if (LB.setRange(0, LB.getNumElements()))
addToWorkList(Inst);
}
/***********************************************************************
* addToWorkList : add instruction to work list if not already there
*
* Enter: Inst = the instruction
*
* This does not actually add to the work list in the initial scan through
* the whole code.
*/
void GenXDeadVectorRemoval::addToWorkList(Instruction *Inst)
{
LLVM_DEBUG(dbgs() << " " << Inst->getName() << " now " << getLiveBits(Inst) << "\n");
if (WorkListSet.insert(Inst).second && WorkListPhase) {
LLVM_DEBUG(dbgs() << " adding " << Inst->getName() << " to work list\n");
WorkList.push(Inst);
}
}
/***********************************************************************
* createLiveBits : create the bitmap of live elements for the given
* instruction if it doesn't exist.
*
* Return: LiveBits object, which contains a pointer to the bitmap for
* this instruction, and a size which is set to 0 if there is no
* bitmap allocated yet for this instruction and Create is false
*/
LiveBits GenXDeadVectorRemoval::createLiveBits(Instruction *Inst)
{
unsigned NumElements = 1;
if (auto *VT = dyn_cast<IGCLLVM::FixedVectorType>(Inst->getType()))
NumElements = VT->getNumElements();
decltype(InstMap)::iterator Iter;
bool WasAnInsertion;
std::tie(Iter, WasAnInsertion) = InstMap.insert(std::make_pair(Inst, LiveBitsStorage{}));
LiveBitsStorage *LBS = &Iter->second;
if (WasAnInsertion) {
// New entry. Set its number of elements.
LBS->setNumElements(NumElements);
}
return LiveBits{LBS, NumElements};
}
/***********************************************************************
* getLiveBits : get the bitmap of live elements for the given instruction
*
* Return: LiveBits object, which contains a pointer to the bitmap for
* this instruction, and a size which is set to 0 if there is no
* bitmap allocated yet for this instruction and Create is false
*/
LiveBits GenXDeadVectorRemoval::getLiveBits(Instruction *Inst)
{
unsigned NumElements = 1;
if (auto *VT = dyn_cast<IGCLLVM::FixedVectorType>(Inst->getType()))
NumElements = VT->getNumElements();
auto i = InstMap.find(Inst);
if (i == InstMap.end())
return LiveBits();
LiveBitsStorage *LBS = &i->second;
return LiveBits(LBS, NumElements);
}
/***********************************************************************
* LiveBits::isAllZero : return true if all bits zero
*/
bool LiveBits::isAllZero() const
{
for (unsigned Idx = 0, End = (NumElements + BitsPerWord - 1) / BitsPerWord;
Idx != End; ++Idx)
if (P[Idx])
return false;
return true;
}
/***********************************************************************
* LiveBits::set : set (or clear) bit
*
* Enter: Idx = element number
* Val = true to set, false to clear, default true
*
* Return: true if the bitmap changed
*/
bool LiveBits::set(unsigned Idx, bool Val)
{
IGC_ASSERT(Idx < NumElements);
IGC_ASSERT(BitsPerWord);
uintptr_t *Ptr = P + Idx / BitsPerWord;
uintptr_t Bit = 1ULL << (Idx % BitsPerWord);
uintptr_t Entry = *Ptr;
if (Val)
Entry |= Bit;
else
Entry &= ~Bit;
bool Ret = Entry != *Ptr;
*Ptr = Entry;
return Ret;
}
/***********************************************************************
* LiveBits::copy : copy all bits from another LiveBits
*/
bool LiveBits::copy(LiveBits Src)
{
IGC_ASSERT(NumElements == Src.NumElements);
IGC_ASSERT(BitsPerWord);
bool Modified = false;
for (unsigned Idx = 0, End = (NumElements + BitsPerWord - 1) / BitsPerWord;
Idx != End; ++Idx) {
Modified |= P[Idx] != Src.P[Idx];
P[Idx] = Src.P[Idx];
}
return Modified;
}
/***********************************************************************
* LiveBits::orBits : or all bits from another LiveBits into this one
*/
bool LiveBits::orBits(LiveBits Src)
{
IGC_ASSERT(NumElements == Src.NumElements);
bool Modified = false;
for (unsigned Idx = 0, End = (NumElements + BitsPerWord - 1) / BitsPerWord;
Idx != End; ++Idx) {
uintptr_t Word = P[Idx] | Src.P[Idx];
Modified |= P[Idx] != Word;
P[Idx] = Word;
}
return Modified;
}
/***********************************************************************
* LiveBits::setRange : set range of bits, returning true if any changed
*/
bool LiveBits::setRange(unsigned Start, unsigned Len)
{
bool Modified = false;
unsigned End = Start + Len;
IGC_ASSERT(End <= NumElements);
while (Start != End) {
unsigned ThisLen = BitsPerWord - (Start & (BitsPerWord - 1));
if (ThisLen > End - Start)
ThisLen = End - Start;
uintptr_t *Entry = P + (Start / BitsPerWord);
uintptr_t Updated = *Entry
| ((uintptr_t)-1LL >> (BitsPerWord - ThisLen))
<< (Start & (BitsPerWord - 1));
if (Updated != *Entry) {
Modified = true;
*Entry = Updated;
}
Start += ThisLen;
}
return Modified;
}
/***********************************************************************
* LiveBits::print : debug print
*/
void LiveBits::print(raw_ostream &OS) const
{
for (unsigned Idx = 0, End = getNumElements(); Idx != End; ++Idx)
OS << get(Idx);
}
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