#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/SmallVector.h"
class VISIBILITY_HIDDEN MachineLICM : public MachineFunctionPass {
const TargetMachine *TM;
const TargetInstrInfo *TII;
- MachineFunction *CurMF; // Current MachineFunction
// Various analyses that we use...
- MachineLoopInfo *LI; // Current MachineLoopInfo
- MachineDominatorTree *DT; // Machine dominator tree for the current Loop
+ MachineLoopInfo *LI; // Current MachineLoopInfo
+ MachineDominatorTree *DT; // Machine dominator tree for the cur loop
MachineRegisterInfo *RegInfo; // Machine register information
// State that is updated as we process loops
- bool Changed; // True if a loop is changed.
- MachineLoop *CurLoop; // The current loop we are working on.
+ bool Changed; // True if a loop is changed.
+ MachineLoop *CurLoop; // The current loop we are working on.
public:
static char ID; // Pass identification, replacement for typeid
- MachineLICM() : MachineFunctionPass((intptr_t)&ID) {}
+ MachineLICM() : MachineFunctionPass(&ID) {}
virtual bool runOnMachineFunction(MachineFunction &MF);
- /// FIXME: Loop preheaders?
- ///
+ // FIXME: Loop preheaders?
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<MachineLoopInfo>();
///
void MoveInstToEndOfBlock(MachineBasicBlock *ToMBB,
MachineBasicBlock *FromMBB,
- MachineInstr *MI) {
- DEBUG({
- DOUT << "Hoisting " << *MI;
- if (ToMBB->getBasicBlock())
- DOUT << " to MachineBasicBlock "
- << ToMBB->getBasicBlock()->getName();
- DOUT << "\n";
- });
-
- MachineBasicBlock::iterator WhereIter = ToMBB->getFirstTerminator();
- MachineBasicBlock::iterator To, From = FromMBB->begin();
-
- while (&*From != MI)
- ++From;
-
- assert(From != FromMBB->end() && "Didn't find instr in BB!");
-
- To = From;
- ToMBB->splice(WhereIter, FromMBB, From, ++To);
- ++NumHoisted;
- }
+ MachineInstr *MI);
/// HoistRegion - Walk the specified region of the CFG (defined by all
/// blocks dominated by the specified block, and that are in the current
///
void Hoist(MachineInstr &MI);
};
-
- char MachineLICM::ID = 0;
- RegisterPass<MachineLICM> X("machine-licm",
- "Machine Loop Invariant Code Motion");
} // end anonymous namespace
+char MachineLICM::ID = 0;
+static RegisterPass<MachineLICM>
+X("machinelicm", "Machine Loop Invariant Code Motion");
+
FunctionPass *llvm::createMachineLICMPass() { return new MachineLICM(); }
/// Hoist expressions out of the specified loop. Note, alias info for inner loop
DOUT << "******** Machine LICM ********\n";
Changed = false;
- CurMF = &MF;
- TM = &CurMF->getTarget();
+ TM = &MF.getTarget();
TII = TM->getInstrInfo();
- RegInfo = &CurMF->getRegInfo();
+ RegInfo = &MF.getRegInfo();
// Get our Loop information...
LI = &getAnalysis<MachineLoopInfo>();
/// effects that aren't captured by the operands or other flags.
///
bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) {
+ const TargetInstrDesc &TID = I.getDesc();
+
+ // Ignore stuff that we obviously can't hoist.
+ if (TID.mayStore() || TID.isCall() || TID.isReturn() || TID.isBranch() ||
+ TID.hasUnmodeledSideEffects())
+ return false;
+
+ if (TID.mayLoad()) {
+ // 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))
+ // 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.
+ return false;
+ }
+
DEBUG({
DOUT << "--- Checking if we can hoist " << I;
if (I.getDesc().getImplicitUses()) {
DOUT << " * Instruction has implicit uses:\n";
- const MRegisterInfo *MRI = TM->getRegisterInfo();
+ const TargetRegisterInfo *TRI = TM->getRegisterInfo();
for (const unsigned *ImpUses = I.getDesc().getImplicitUses();
*ImpUses; ++ImpUses)
- DOUT << " -> " << MRI->getName(*ImpUses) << "\n";
+ DOUT << " -> " << TRI->getName(*ImpUses) << "\n";
}
if (I.getDesc().getImplicitDefs()) {
DOUT << " * Instruction has implicit defines:\n";
- const MRegisterInfo *MRI = TM->getRegisterInfo();
+ const TargetRegisterInfo *TRI = TM->getRegisterInfo();
for (const unsigned *ImpDefs = I.getDesc().getImplicitDefs();
*ImpDefs; ++ImpDefs)
- DOUT << " -> " << MRI->getName(*ImpDefs) << "\n";
+ DOUT << " -> " << TRI->getName(*ImpDefs) << "\n";
}
-
- if (TII->hasUnmodelledSideEffects(&I))
- DOUT << " * Instruction has side effects.\n";
});
- // The instruction is loop invariant if all of its operands are loop-invariant
+ if (I.getDesc().getImplicitDefs() || I.getDesc().getImplicitUses()) {
+ DOUT << "Cannot hoist with implicit defines or uses\n";
+ return false;
+ }
+
+ // The instruction is loop invariant if all of its operands are.
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
const MachineOperand &MO = I.getOperand(i);
- if (!(MO.isRegister() && MO.getReg() && MO.isUse()))
+ if (!MO.isReg())
+ continue;
+
+ if (MO.isDef() && TargetRegisterInfo::isPhysicalRegister(MO.getReg()))
+ // Don't hoist an instruction that defines a physical register.
+ return false;
+
+ if (!MO.isUse())
continue;
unsigned Reg = MO.getReg();
+ if (Reg == 0) continue;
// Don't hoist instructions that access physical registers.
- if (!MRegisterInfo::isVirtualRegister(Reg))
+ if (TargetRegisterInfo::isPhysicalRegister(Reg))
return false;
- assert(RegInfo->getVRegDef(Reg)&&"Machine instr not mapped for this vreg?");
+ assert(RegInfo->getVRegDef(Reg) &&
+ "Machine instr not mapped for this vreg?!");
// If the loop contains the definition of an operand, then the instruction
// isn't loop invariant.
return false;
}
- // Don't hoist something that has unmodelled side effects.
- if (TII->hasUnmodelledSideEffects(&I)) return false;
-
// If we got this far, the instruction is loop invariant!
return true;
}
-/// Hoist - When an instruction is found to only use loop invariant operands
-/// that is safe to hoist, this instruction is called to do the dirty work.
+/// MoveInstToEndOfBlock - Moves the machine instruction to the bottom of the
+/// predecessor basic block (but before the terminator instructions).
+///
+void MachineLICM::MoveInstToEndOfBlock(MachineBasicBlock *ToMBB,
+ MachineBasicBlock *FromMBB,
+ MachineInstr *MI) {
+ DEBUG({
+ DOUT << "Hoisting " << *MI;
+ if (ToMBB->getBasicBlock())
+ DOUT << " to MachineBasicBlock "
+ << ToMBB->getBasicBlock()->getName();
+ if (FromMBB->getBasicBlock())
+ DOUT << " from MachineBasicBlock "
+ << FromMBB->getBasicBlock()->getName();
+ DOUT << "\n";
+ });
+
+ MachineBasicBlock::iterator WhereIter = ToMBB->getFirstTerminator();
+ MachineBasicBlock::iterator To, From = FromMBB->begin();
+
+ while (&*From != MI)
+ ++From;
+
+ assert(From != FromMBB->end() && "Didn't find instr in BB!");
+
+ To = From;
+ ToMBB->splice(WhereIter, FromMBB, From, ++To);
+ ++NumHoisted;
+}
+
+/// Hoist - When an instruction is found to use only loop invariant operands
+/// that are safe to hoist, this instruction is called to do the dirty work.
///
void MachineLICM::Hoist(MachineInstr &MI) {
if (!IsLoopInvariantInst(MI)) return;
// is forbidden.
if (Preds.empty() || Preds.size() != 1) return;
- // Check that the predecessor is qualified to take the hoisted
- // instruction. I.e., there is only one edge from the predecessor, and it's to
- // the loop header.
+ // Check that the predecessor is qualified to take the hoisted instruction.
+ // I.e., there is only one edge from the predecessor, and it's to the loop
+ // header.
MachineBasicBlock *MBB = Preds.front();
// FIXME: We are assuming at first that the basic block coming into this loop
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