namespace llvm {
+class AliasAnalysis;
class TargetInstrDesc;
class TargetInstrInfo;
class TargetRegisterInfo;
/// have no volatile memory references.
bool hasVolatileMemoryRef() const;
+ /// isInvariantLoad - Return true if this instruction is loading from a
+ /// location whose value is invariant across the function. For example,
+ /// loading a value from the constant pool or from from the argument area of
+ /// a function if it does not change. This should only return true of *all*
+ /// loads the instruction does are invariant (if it does multiple loads).
+ bool isInvariantLoad(AliasAnalysis *AA = 0) const;
+
//
// Debugging support
//
unsigned DestReg, unsigned SubIdx,
const MachineInstr *Orig) const = 0;
- /// isInvariantLoad - Return true if the specified instruction (which is
- /// marked mayLoad) is loading from a location whose value is invariant across
- /// the function. For example, loading a value from the constant pool or from
- /// from the argument area of a function if it does not change. This should
- /// only return true of *all* loads the instruction does are invariant (if it
- /// does multiple loads).
- virtual bool isInvariantLoad(const MachineInstr *MI) const {
- return false;
- }
-
/// convertToThreeAddress - This method must be implemented by targets that
/// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
/// may be able to convert a two-address instruction into one or more true
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetInstrDesc.h"
#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LeakDetector.h"
// destination. The check for isInvariantLoad gives the targe the chance to
// classify the load as always returning a constant, e.g. a constant pool
// load.
- if (TID->mayLoad() && !TII->isInvariantLoad(this))
+ if (TID->mayLoad() && !isInvariantLoad())
// Otherwise, this is a real load. If there is a store between the load and
// end of block, or if the load is volatile, we can't move it.
return !SawStore && !hasVolatileMemoryRef();
return false;
}
+/// isInvariantLoad - Return true if this instruction is loading from a
+/// location whose value is invariant across the function. For example,
+/// loading a value from the constant pool or from from the argument area
+/// of a function if it does not change. This should only return true of
+/// *all* loads the instruction does are invariant (if it does multiple loads).
+bool MachineInstr::isInvariantLoad(AliasAnalysis *AA) const {
+ // If the instruction doesn't load at all, it isn't an invariant load.
+ if (!TID->mayLoad())
+ return false;
+
+ // If the instruction has lost its memoperands, conservatively assume that
+ // it may not be an invariant load.
+ if (memoperands_empty())
+ return false;
+
+ const MachineFrameInfo *MFI = getParent()->getParent()->getFrameInfo();
+
+ for (mmo_iterator I = memoperands_begin(),
+ E = memoperands_end(); I != E; ++I) {
+ if ((*I)->isVolatile()) return false;
+ if ((*I)->isStore()) return false;
+
+ if (const Value *V = (*I)->getValue()) {
+ // A load from a constant PseudoSourceValue is invariant.
+ if (const PseudoSourceValue *PSV = dyn_cast<PseudoSourceValue>(V))
+ if (PSV->isConstant(MFI))
+ continue;
+ // If we have an AliasAnalysis, ask it whether the memory is constant.
+ if (AA && AA->pointsToConstantMemory(V))
+ continue;
+ }
+
+ // Otherwise assume conservatively.
+ return false;
+ }
+
+ // Everything checks out.
+ return true;
+}
+
void MachineInstr::dump() const {
errs() << " " << *this;
}
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
BitVector AllocatableSet;
// Various analyses that we use...
+ AliasAnalysis *AA; // Alias analysis info.
MachineLoopInfo *LI; // Current MachineLoopInfo
MachineDominatorTree *DT; // Machine dominator tree for the cur loop
MachineRegisterInfo *RegInfo; // Machine register information
AU.setPreservesCFG();
AU.addRequired<MachineLoopInfo>();
AU.addRequired<MachineDominatorTree>();
+ AU.addRequired<AliasAnalysis>();
AU.addPreserved<MachineLoopInfo>();
AU.addPreserved<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
// Get our Loop information...
LI = &getAnalysis<MachineLoopInfo>();
DT = &getAnalysis<MachineDominatorTree>();
+ AA = &getAnalysis<AliasAnalysis>();
for (MachineLoopInfo::iterator
I = LI->begin(), E = LI->end(); I != E; ++I) {
// Okay, this instruction does a load. As a refinement, we allow the target
// to decide whether the loaded value is actually a constant. If so, we can
// actually use it as a load.
- if (!TII->isInvariantLoad(&I))
+ if (!I.isInvariantLoad(AA))
// FIXME: we should be able to sink loads with no other side effects if
// there is nothing that can change memory from here until the end of
// block. This is a trivial form of alias analysis.
// Don't hoist an instruction that uses or defines a physical register.
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
- // If this is a physical register use, we can't move it. If it is a def,
- // we can move it, but only if the def is dead.
if (MO.isUse()) {
// If the physreg has no defs anywhere, it's just an ambient register
// and we can freely move its uses. Alternatively, if it's allocatable,
if (Reg == 0) continue;
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
- // If this is a physical register use, we can't move it. If it is a def,
- // we can move it, but only if the def is dead.
if (MO.isUse()) {
// If the physreg has no defs anywhere, it's just an ambient register
// and we can freely move its uses. Alternatively, if it's allocatable,
// Treat all other stores conservatively.
goto new_chain;
} else if (TID.mayLoad()) {
- if (TII->isInvariantLoad(MI)) {
+ if (MI->isInvariantLoad()) {
// Invariant load, no chain dependencies needed!
} else if (const Value *V = getUnderlyingObjectForInstr(MI)) {
// A load from a specific PseudoSourceValue. Add precise dependencies.
return 0;
}
-bool SystemZInstrInfo::isInvariantLoad(const MachineInstr *MI) const {
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- const MachineOperand &MO = MI->getOperand(i);
- // Loads from constant pools are trivially invariant.
- if (MO.isCPI())
- return true;
-
- if (MO.isGlobal())
- return isGVStub(MO.getGlobal(), TM);
-
- // If this is a load from an invariant stack slot, the load is a constant.
- if (MO.isFI()) {
- const MachineFrameInfo &MFI =
- *MI->getParent()->getParent()->getFrameInfo();
- int Idx = MO.getIndex();
- return MFI.isFixedObjectIndex(Idx) && MFI.isImmutableObjectIndex(Idx);
- }
- }
-
- // All other instances of these instructions are presumed to have other
- // issues.
- return false;
-}
-
bool
SystemZInstrInfo::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
unsigned &SrcSubIdx, unsigned &DstSubIdx) const;
unsigned isLoadFromStackSlot(const MachineInstr *MI, int &FrameIndex) const;
unsigned isStoreToStackSlot(const MachineInstr *MI, int &FrameIndex) const;
- bool isInvariantLoad(const MachineInstr *MI) const;
virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
NewMI->getOperand(0).setSubReg(SubIdx);
}
-/// isInvariantLoad - Return true if the specified instruction (which is marked
-/// mayLoad) is loading from a location whose value is invariant across the
-/// function. For example, loading a value from the constant pool or from
-/// from the argument area of a function if it does not change. This should
-/// only return true of *all* loads the instruction does are invariant (if it
-/// does multiple loads).
-bool X86InstrInfo::isInvariantLoad(const MachineInstr *MI) const {
- // This code cares about loads from three cases: constant pool entries,
- // invariant argument slots, and global stubs. In order to handle these cases
- // for all of the myriad of X86 instructions, we just scan for a CP/FI/GV
- // operand and base our analysis on it. This is safe because the address of
- // none of these three cases is ever used as anything other than a load base
- // and X86 doesn't have any instructions that load from multiple places.
-
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- const MachineOperand &MO = MI->getOperand(i);
- // Loads from constant pools are trivially invariant.
- if (MO.isCPI())
- return true;
-
- if (MO.isGlobal())
- return isGlobalStubReference(MO.getTargetFlags());
-
- // If this is a load from an invariant stack slot, the load is a constant.
- if (MO.isFI()) {
- const MachineFrameInfo &MFI =
- *MI->getParent()->getParent()->getFrameInfo();
- int Idx = MO.getIndex();
- return MFI.isFixedObjectIndex(Idx) && MFI.isImmutableObjectIndex(Idx);
- }
- }
-
- // All other instances of these instructions are presumed to have other
- // issues.
- return false;
-}
-
/// hasLiveCondCodeDef - True if MI has a condition code def, e.g. EFLAGS, that
/// is not marked dead.
static bool hasLiveCondCodeDef(MachineInstr *MI) {
unsigned DestReg, unsigned SubIdx,
const MachineInstr *Orig) const;
- bool isInvariantLoad(const MachineInstr *MI) const;
-
/// convertToThreeAddress - This method must be implemented by targets that
/// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
/// may be able to convert a two-address instruction into a true
return 0;
}
-/// isInvariantLoad - Return true if the specified instruction (which is marked
-/// mayLoad) is loading from a location whose value is invariant across the
-/// function. For example, loading a value from the constant pool or from
-/// from the argument area of a function if it does not change. This should
-/// only return true of *all* loads the instruction does are invariant (if it
-/// does multiple loads).
-bool
-XCoreInstrInfo::isInvariantLoad(const MachineInstr *MI) const {
- // Loads from constants pools and loads from invariant argument slots are
- // invariant
- int Opcode = MI->getOpcode();
- if (Opcode == XCore::LDWCP_ru6 || Opcode == XCore::LDWCP_lru6) {
- return MI->getOperand(1).isCPI();
- }
- int FrameIndex;
- if (isLoadFromStackSlot(MI, FrameIndex)) {
- const MachineFrameInfo &MFI =
- *MI->getParent()->getParent()->getFrameInfo();
- return MFI.isFixedObjectIndex(FrameIndex) &&
- MFI.isImmutableObjectIndex(FrameIndex);
- }
- return false;
-}
-
//===----------------------------------------------------------------------===//
// Branch Analysis
//===----------------------------------------------------------------------===//
virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
int &FrameIndex) const;
- virtual bool isInvariantLoad(const MachineInstr *MI) const;
-
virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
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