namespace llvm {
class TargetInstrDesc;
+class TargetInstrInfo;
class TargetRegisterInfo;
template <typename T> struct ilist_traits;
bool addRegisterDead(unsigned IncomingReg, const TargetRegisterInfo *RegInfo,
bool AddIfNotFound = false);
- /// copyKillDeadInfo - copies killed/dead information from one instr to another
+ /// copyKillDeadInfo - Copies killed/dead information from one instr to another
void copyKillDeadInfo(MachineInstr *OldMI,
const TargetRegisterInfo *RegInfo);
+ /// isSafeToMove - Return true if it is safe to this instruction. If SawStore
+ /// true, it means there is a store (or call) between the instruction the
+ /// localtion and its intended destination.
+ bool isSafeToMove(const TargetInstrInfo *TII, bool &SawStore);
+
//
// Debugging support
//
/// copyPredicates - Copies predicate operand(s) from MI.
void MachineInstr::copyPredicates(const MachineInstr *MI) {
const TargetInstrDesc &TID = MI->getDesc();
- if (TID.isPredicable()) {
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- if (TID.OpInfo[i].isPredicate()) {
- // Predicated operands must be last operands.
- addOperand(MI->getOperand(i));
- }
+ if (!TID.isPredicable())
+ return;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ if (TID.OpInfo[i].isPredicate()) {
+ // Predicated operands must be last operands.
+ addOperand(MI->getOperand(i));
}
}
}
+/// isSafeToMove - Return true if it is safe to this instruction. If SawStore
+/// true, it means there is a store (or call) between the instruction the
+/// localtion and its intended destination.
+bool MachineInstr::isSafeToMove(const TargetInstrInfo *TII, bool &SawStore) {
+ // Ignore stuff that we obviously can't move.
+ if (TID->mayStore() || TID->isCall()) {
+ SawStore = true;
+ return false;
+ }
+ if (TID->isReturn() || TID->isBranch() || TID->hasUnmodeledSideEffects())
+ return false;
+
+ // See if this instruction does a load. If so, we have to guarantee that the
+ // loaded value doesn't change between the load and the its intended
+ // 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)) {
+ // Otherwise, this is a real load. If there is a store between the load and
+ // end of block, we can't sink the load.
+ //
+ // FIXME: we can't do this transformation until we know that the load is
+ // not volatile, and machineinstrs don't keep this info. :(
+ //
+ //if (SawStore)
+ return false;
+ }
+ return true;
+}
+
void MachineInstr::dump() const {
cerr << " " << *this;
}
/// SinkInstruction - Determine whether it is safe to sink the specified machine
/// instruction out of its current block into a successor.
bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
- const TargetInstrDesc &TID = MI->getDesc();
-
- // Ignore stuff that we obviously can't sink.
- if (TID.mayStore() || TID.isCall()) {
- SawStore = true;
- return false;
- }
- if (TID.isReturn() || TID.isBranch() || TID.hasUnmodeledSideEffects())
+ // Check if it's safe to move the instruction.
+ if (!MI->isSafeToMove(TII, SawStore))
return false;
-
- // See if this instruction does a load. If so, we have to guarantee that the
- // loaded value doesn't change between the load and the end of block. 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(MI)) {
- // Otherwise, this is a real load. If there is a store between the load and
- // end of block, we can't sink the load.
- //
- // FIXME: we can't do this transformation until we know that the load is
- // not volatile, and machineinstrs don't keep this info. :(
- //
- //if (SawStore)
- return false;
- }
// FIXME: This should include support for sinking instructions within the
// block they are currently in to shorten the live ranges. We often get