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Refactor some code out of MachineSink into a MachineInstr query.

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llvm-svn: 48311
This commit is contained in:
Evan Cheng 2008-03-13 00:44:09 +00:00
parent 1e54f7c2b6
commit b9fc5d6d07
3 changed files with 45 additions and 30 deletions
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8
include/llvm/CodeGen/MachineInstr.h
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@ -22,6 +22,7 @@
namespace llvm {
class TargetInstrDesc;
class TargetInstrInfo;
class TargetRegisterInfo;
template <typename T> struct ilist_traits;
@ -229,10 +230,15 @@ public:
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
//

42
lib/CodeGen/MachineInstr.cpp
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@ -628,16 +628,46 @@ void MachineInstr::copyKillDeadInfo(const MachineInstr *MI) {
/// 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;
}

25
lib/CodeGen/MachineSink.cpp
View File

@ -132,30 +132,9 @@ bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
/// 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;
// Check if it's safe to move the instruction.
if (!MI->isSafeToMove(TII, SawStore))
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 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