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-rw-r--r--lib/Transforms/Utils/AddrModeMatcher.cpp577
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diff --git a/lib/Transforms/Utils/AddrModeMatcher.cpp b/lib/Transforms/Utils/AddrModeMatcher.cpp
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-//===- AddrModeMatcher.cpp - Addressing mode matching facility --*- C++ -*-===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements target addressing mode matcher class.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/Utils/AddrModeMatcher.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/GlobalValue.h"
-#include "llvm/Instruction.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/DataLayout.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/PatternMatch.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Support/CallSite.h"
-
-using namespace llvm;
-using namespace llvm::PatternMatch;
-
-void ExtAddrMode::print(raw_ostream &OS) const {
- bool NeedPlus = false;
- OS << "[";
- if (BaseGV) {
- OS << (NeedPlus ? " + " : "")
- << "GV:";
- WriteAsOperand(OS, BaseGV, /*PrintType=*/false);
- NeedPlus = true;
- }
-
- if (BaseOffs)
- OS << (NeedPlus ? " + " : "") << BaseOffs, NeedPlus = true;
-
- if (BaseReg) {
- OS << (NeedPlus ? " + " : "")
- << "Base:";
- WriteAsOperand(OS, BaseReg, /*PrintType=*/false);
- NeedPlus = true;
- }
- if (Scale) {
- OS << (NeedPlus ? " + " : "")
- << Scale << "*";
- WriteAsOperand(OS, ScaledReg, /*PrintType=*/false);
- NeedPlus = true;
- }
-
- OS << ']';
-}
-
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-void ExtAddrMode::dump() const {
- print(dbgs());
- dbgs() << '\n';
-}
-#endif
-
-
-/// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
-/// Return true and update AddrMode if this addr mode is legal for the target,
-/// false if not.
-bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale,
- unsigned Depth) {
- // If Scale is 1, then this is the same as adding ScaleReg to the addressing
- // mode. Just process that directly.
- if (Scale == 1)
- return MatchAddr(ScaleReg, Depth);
-
- // If the scale is 0, it takes nothing to add this.
- if (Scale == 0)
- return true;
-
- // If we already have a scale of this value, we can add to it, otherwise, we
- // need an available scale field.
- if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
- return false;
-
- ExtAddrMode TestAddrMode = AddrMode;
-
- // Add scale to turn X*4+X*3 -> X*7. This could also do things like
- // [A+B + A*7] -> [B+A*8].
- TestAddrMode.Scale += Scale;
- TestAddrMode.ScaledReg = ScaleReg;
-
- // If the new address isn't legal, bail out.
- if (!TLI.isLegalAddressingMode(TestAddrMode, AccessTy))
- return false;
-
- // It was legal, so commit it.
- AddrMode = TestAddrMode;
-
- // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
- // to see if ScaleReg is actually X+C. If so, we can turn this into adding
- // X*Scale + C*Scale to addr mode.
- ConstantInt *CI = 0; Value *AddLHS = 0;
- if (isa<Instruction>(ScaleReg) && // not a constant expr.
- match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
- TestAddrMode.ScaledReg = AddLHS;
- TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
-
- // If this addressing mode is legal, commit it and remember that we folded
- // this instruction.
- if (TLI.isLegalAddressingMode(TestAddrMode, AccessTy)) {
- AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
- AddrMode = TestAddrMode;
- return true;
- }
- }
-
- // Otherwise, not (x+c)*scale, just return what we have.
- return true;
-}
-
-/// MightBeFoldableInst - This is a little filter, which returns true if an
-/// addressing computation involving I might be folded into a load/store
-/// accessing it. This doesn't need to be perfect, but needs to accept at least
-/// the set of instructions that MatchOperationAddr can.
-static bool MightBeFoldableInst(Instruction *I) {
- switch (I->getOpcode()) {
- case Instruction::BitCast:
- // Don't touch identity bitcasts.
- if (I->getType() == I->getOperand(0)->getType())
- return false;
- return I->getType()->isPointerTy() || I->getType()->isIntegerTy();
- case Instruction::PtrToInt:
- // PtrToInt is always a noop, as we know that the int type is pointer sized.
- return true;
- case Instruction::IntToPtr:
- // We know the input is intptr_t, so this is foldable.
- return true;
- case Instruction::Add:
- return true;
- case Instruction::Mul:
- case Instruction::Shl:
- // Can only handle X*C and X << C.
- return isa<ConstantInt>(I->getOperand(1));
- case Instruction::GetElementPtr:
- return true;
- default:
- return false;
- }
-}
-
-
-/// MatchOperationAddr - Given an instruction or constant expr, see if we can
-/// fold the operation into the addressing mode. If so, update the addressing
-/// mode and return true, otherwise return false without modifying AddrMode.
-bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
- unsigned Depth) {
- // Avoid exponential behavior on extremely deep expression trees.
- if (Depth >= 5) return false;
-
- switch (Opcode) {
- case Instruction::PtrToInt:
- // PtrToInt is always a noop, as we know that the int type is pointer sized.
- return MatchAddr(AddrInst->getOperand(0), Depth);
- case Instruction::IntToPtr:
- // This inttoptr is a no-op if the integer type is pointer sized.
- if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
- TLI.getPointerTy())
- return MatchAddr(AddrInst->getOperand(0), Depth);
- return false;
- case Instruction::BitCast:
- // BitCast is always a noop, and we can handle it as long as it is
- // int->int or pointer->pointer (we don't want int<->fp or something).
- if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||
- AddrInst->getOperand(0)->getType()->isIntegerTy()) &&
- // Don't touch identity bitcasts. These were probably put here by LSR,
- // and we don't want to mess around with them. Assume it knows what it
- // is doing.
- AddrInst->getOperand(0)->getType() != AddrInst->getType())
- return MatchAddr(AddrInst->getOperand(0), Depth);
- return false;
- case Instruction::Add: {
- // Check to see if we can merge in the RHS then the LHS. If so, we win.
- ExtAddrMode BackupAddrMode = AddrMode;
- unsigned OldSize = AddrModeInsts.size();
- if (MatchAddr(AddrInst->getOperand(1), Depth+1) &&
- MatchAddr(AddrInst->getOperand(0), Depth+1))
- return true;
-
- // Restore the old addr mode info.
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
-
- // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
- if (MatchAddr(AddrInst->getOperand(0), Depth+1) &&
- MatchAddr(AddrInst->getOperand(1), Depth+1))
- return true;
-
- // Otherwise we definitely can't merge the ADD in.
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- break;
- }
- //case Instruction::Or:
- // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
- //break;
- case Instruction::Mul:
- case Instruction::Shl: {
- // Can only handle X*C and X << C.
- ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
- if (!RHS) return false;
- int64_t Scale = RHS->getSExtValue();
- if (Opcode == Instruction::Shl)
- Scale = 1LL << Scale;
-
- return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth);
- }
- case Instruction::GetElementPtr: {
- // Scan the GEP. We check it if it contains constant offsets and at most
- // one variable offset.
- int VariableOperand = -1;
- unsigned VariableScale = 0;
-
- int64_t ConstantOffset = 0;
- const DataLayout *TD = TLI.getDataLayout();
- gep_type_iterator GTI = gep_type_begin(AddrInst);
- for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
- if (StructType *STy = dyn_cast<StructType>(*GTI)) {
- const StructLayout *SL = TD->getStructLayout(STy);
- unsigned Idx =
- cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
- ConstantOffset += SL->getElementOffset(Idx);
- } else {
- uint64_t TypeSize = TD->getTypeAllocSize(GTI.getIndexedType());
- if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
- ConstantOffset += CI->getSExtValue()*TypeSize;
- } else if (TypeSize) { // Scales of zero don't do anything.
- // We only allow one variable index at the moment.
- if (VariableOperand != -1)
- return false;
-
- // Remember the variable index.
- VariableOperand = i;
- VariableScale = TypeSize;
- }
- }
- }
-
- // A common case is for the GEP to only do a constant offset. In this case,
- // just add it to the disp field and check validity.
- if (VariableOperand == -1) {
- AddrMode.BaseOffs += ConstantOffset;
- if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
- // Check to see if we can fold the base pointer in too.
- if (MatchAddr(AddrInst->getOperand(0), Depth+1))
- return true;
- }
- AddrMode.BaseOffs -= ConstantOffset;
- return false;
- }
-
- // Save the valid addressing mode in case we can't match.
- ExtAddrMode BackupAddrMode = AddrMode;
- unsigned OldSize = AddrModeInsts.size();
-
- // See if the scale and offset amount is valid for this target.
- AddrMode.BaseOffs += ConstantOffset;
-
- // Match the base operand of the GEP.
- if (!MatchAddr(AddrInst->getOperand(0), Depth+1)) {
- // If it couldn't be matched, just stuff the value in a register.
- if (AddrMode.HasBaseReg) {
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- return false;
- }
- AddrMode.HasBaseReg = true;
- AddrMode.BaseReg = AddrInst->getOperand(0);
- }
-
- // Match the remaining variable portion of the GEP.
- if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
- Depth)) {
- // If it couldn't be matched, try stuffing the base into a register
- // instead of matching it, and retrying the match of the scale.
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- if (AddrMode.HasBaseReg)
- return false;
- AddrMode.HasBaseReg = true;
- AddrMode.BaseReg = AddrInst->getOperand(0);
- AddrMode.BaseOffs += ConstantOffset;
- if (!MatchScaledValue(AddrInst->getOperand(VariableOperand),
- VariableScale, Depth)) {
- // If even that didn't work, bail.
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- return false;
- }
- }
-
- return true;
- }
- }
- return false;
-}
-
-/// MatchAddr - If we can, try to add the value of 'Addr' into the current
-/// addressing mode. If Addr can't be added to AddrMode this returns false and
-/// leaves AddrMode unmodified. This assumes that Addr is either a pointer type
-/// or intptr_t for the target.
-///
-bool AddressingModeMatcher::MatchAddr(Value *Addr, unsigned Depth) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
- // Fold in immediates if legal for the target.
- AddrMode.BaseOffs += CI->getSExtValue();
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.BaseOffs -= CI->getSExtValue();
- } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
- // If this is a global variable, try to fold it into the addressing mode.
- if (AddrMode.BaseGV == 0) {
- AddrMode.BaseGV = GV;
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.BaseGV = 0;
- }
- } else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
- ExtAddrMode BackupAddrMode = AddrMode;
- unsigned OldSize = AddrModeInsts.size();
-
- // Check to see if it is possible to fold this operation.
- if (MatchOperationAddr(I, I->getOpcode(), Depth)) {
- // Okay, it's possible to fold this. Check to see if it is actually
- // *profitable* to do so. We use a simple cost model to avoid increasing
- // register pressure too much.
- if (I->hasOneUse() ||
- IsProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
- AddrModeInsts.push_back(I);
- return true;
- }
-
- // It isn't profitable to do this, roll back.
- //cerr << "NOT FOLDING: " << *I;
- AddrMode = BackupAddrMode;
- AddrModeInsts.resize(OldSize);
- }
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
- if (MatchOperationAddr(CE, CE->getOpcode(), Depth))
- return true;
- } else if (isa<ConstantPointerNull>(Addr)) {
- // Null pointer gets folded without affecting the addressing mode.
- return true;
- }
-
- // Worse case, the target should support [reg] addressing modes. :)
- if (!AddrMode.HasBaseReg) {
- AddrMode.HasBaseReg = true;
- AddrMode.BaseReg = Addr;
- // Still check for legality in case the target supports [imm] but not [i+r].
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.HasBaseReg = false;
- AddrMode.BaseReg = 0;
- }
-
- // If the base register is already taken, see if we can do [r+r].
- if (AddrMode.Scale == 0) {
- AddrMode.Scale = 1;
- AddrMode.ScaledReg = Addr;
- if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
- return true;
- AddrMode.Scale = 0;
- AddrMode.ScaledReg = 0;
- }
- // Couldn't match.
- return false;
-}
-
-
-/// IsOperandAMemoryOperand - Check to see if all uses of OpVal by the specified
-/// inline asm call are due to memory operands. If so, return true, otherwise
-/// return false.
-static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
- const TargetLowering &TLI) {
- TargetLowering::AsmOperandInfoVector TargetConstraints = TLI.ParseConstraints(ImmutableCallSite(CI));
- for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
- TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
-
- // Compute the constraint code and ConstraintType to use.
- TLI.ComputeConstraintToUse(OpInfo, SDValue());
-
- // If this asm operand is our Value*, and if it isn't an indirect memory
- // operand, we can't fold it!
- if (OpInfo.CallOperandVal == OpVal &&
- (OpInfo.ConstraintType != TargetLowering::C_Memory ||
- !OpInfo.isIndirect))
- return false;
- }
-
- return true;
-}
-
-
-/// FindAllMemoryUses - Recursively walk all the uses of I until we find a
-/// memory use. If we find an obviously non-foldable instruction, return true.
-/// Add the ultimately found memory instructions to MemoryUses.
-static bool FindAllMemoryUses(Instruction *I,
- SmallVectorImpl<std::pair<Instruction*,unsigned> > &MemoryUses,
- SmallPtrSet<Instruction*, 16> &ConsideredInsts,
- const TargetLowering &TLI) {
- // If we already considered this instruction, we're done.
- if (!ConsideredInsts.insert(I))
- return false;
-
- // If this is an obviously unfoldable instruction, bail out.
- if (!MightBeFoldableInst(I))
- return true;
-
- // Loop over all the uses, recursively processing them.
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
- UI != E; ++UI) {
- User *U = *UI;
-
- if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
- MemoryUses.push_back(std::make_pair(LI, UI.getOperandNo()));
- continue;
- }
-
- if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
- unsigned opNo = UI.getOperandNo();
- if (opNo == 0) return true; // Storing addr, not into addr.
- MemoryUses.push_back(std::make_pair(SI, opNo));
- continue;
- }
-
- if (CallInst *CI = dyn_cast<CallInst>(U)) {
- InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
- if (!IA) return true;
-
- // If this is a memory operand, we're cool, otherwise bail out.
- if (!IsOperandAMemoryOperand(CI, IA, I, TLI))
- return true;
- continue;
- }
-
- if (FindAllMemoryUses(cast<Instruction>(U), MemoryUses, ConsideredInsts,
- TLI))
- return true;
- }
-
- return false;
-}
-
-
-/// ValueAlreadyLiveAtInst - Retrn true if Val is already known to be live at
-/// the use site that we're folding it into. If so, there is no cost to
-/// include it in the addressing mode. KnownLive1 and KnownLive2 are two values
-/// that we know are live at the instruction already.
-bool AddressingModeMatcher::ValueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
- Value *KnownLive2) {
- // If Val is either of the known-live values, we know it is live!
- if (Val == 0 || Val == KnownLive1 || Val == KnownLive2)
- return true;
-
- // All values other than instructions and arguments (e.g. constants) are live.
- if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
-
- // If Val is a constant sized alloca in the entry block, it is live, this is
- // true because it is just a reference to the stack/frame pointer, which is
- // live for the whole function.
- if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
- if (AI->isStaticAlloca())
- return true;
-
- // Check to see if this value is already used in the memory instruction's
- // block. If so, it's already live into the block at the very least, so we
- // can reasonably fold it.
- return Val->isUsedInBasicBlock(MemoryInst->getParent());
-}
-
-
-
-/// IsProfitableToFoldIntoAddressingMode - It is possible for the addressing
-/// mode of the machine to fold the specified instruction into a load or store
-/// that ultimately uses it. However, the specified instruction has multiple
-/// uses. Given this, it may actually increase register pressure to fold it
-/// into the load. For example, consider this code:
-///
-/// X = ...
-/// Y = X+1
-/// use(Y) -> nonload/store
-/// Z = Y+1
-/// load Z
-///
-/// In this case, Y has multiple uses, and can be folded into the load of Z
-/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
-/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
-/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
-/// number of computations either.
-///
-/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
-/// X was live across 'load Z' for other reasons, we actually *would* want to
-/// fold the addressing mode in the Z case. This would make Y die earlier.
-bool AddressingModeMatcher::
-IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
- ExtAddrMode &AMAfter) {
- if (IgnoreProfitability) return true;
-
- // AMBefore is the addressing mode before this instruction was folded into it,
- // and AMAfter is the addressing mode after the instruction was folded. Get
- // the set of registers referenced by AMAfter and subtract out those
- // referenced by AMBefore: this is the set of values which folding in this
- // address extends the lifetime of.
- //
- // Note that there are only two potential values being referenced here,
- // BaseReg and ScaleReg (global addresses are always available, as are any
- // folded immediates).
- Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
-
- // If the BaseReg or ScaledReg was referenced by the previous addrmode, their
- // lifetime wasn't extended by adding this instruction.
- if (ValueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
- BaseReg = 0;
- if (ValueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
- ScaledReg = 0;
-
- // If folding this instruction (and it's subexprs) didn't extend any live
- // ranges, we're ok with it.
- if (BaseReg == 0 && ScaledReg == 0)
- return true;
-
- // If all uses of this instruction are ultimately load/store/inlineasm's,
- // check to see if their addressing modes will include this instruction. If
- // so, we can fold it into all uses, so it doesn't matter if it has multiple
- // uses.
- SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
- SmallPtrSet<Instruction*, 16> ConsideredInsts;
- if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI))
- return false; // Has a non-memory, non-foldable use!
-
- // Now that we know that all uses of this instruction are part of a chain of
- // computation involving only operations that could theoretically be folded
- // into a memory use, loop over each of these uses and see if they could
- // *actually* fold the instruction.
- SmallVector<Instruction*, 32> MatchedAddrModeInsts;
- for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
- Instruction *User = MemoryUses[i].first;
- unsigned OpNo = MemoryUses[i].second;
-
- // Get the access type of this use. If the use isn't a pointer, we don't
- // know what it accesses.
- Value *Address = User->getOperand(OpNo);
- if (!Address->getType()->isPointerTy())
- return false;
- Type *AddressAccessTy =
- cast<PointerType>(Address->getType())->getElementType();
-
- // Do a match against the root of this address, ignoring profitability. This
- // will tell us if the addressing mode for the memory operation will
- // *actually* cover the shared instruction.
- ExtAddrMode Result;
- AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, AddressAccessTy,
- MemoryInst, Result);
- Matcher.IgnoreProfitability = true;
- bool Success = Matcher.MatchAddr(Address, 0);
- (void)Success; assert(Success && "Couldn't select *anything*?");
-
- // If the match didn't cover I, then it won't be shared by it.
- if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(),
- I) == MatchedAddrModeInsts.end())
- return false;
-
- MatchedAddrModeInsts.clear();
- }
-
- return true;
-}
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