//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "machine-licm"
-#include "llvm/ADT/IndexedMap.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Target/MRegisterInfo.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
using namespace llvm;
-namespace {
- // Hidden options to help debugging
- cl::opt<bool>
- PerformLICM("machine-licm",
- cl::init(false), cl::Hidden,
- cl::desc("Perform loop-invariant code motion on machine code"));
-}
-
STATISTIC(NumHoisted, "Number of machine instructions hoisted out of loops");
namespace {
AU.setPreservesCFG();
AU.addRequired<MachineLoopInfo>();
AU.addRequired<MachineDominatorTree>();
+ AU.addPreserved<MachineLoopInfo>();
+ AU.addPreserved<MachineDominatorTree>();
+ MachineFunctionPass::getAnalysisUsage(AU);
}
private:
/// VisitAllLoops - Visit all of the loops in depth first order and try to
/// loop.
///
bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
- if (!PerformLICM) return false; // For debugging.
-
DOUT << "******** Machine LICM ********\n";
Changed = false;
CurMF = &MF;
TM = &CurMF->getTarget();
TII = TM->getInstrInfo();
- RegInfo = new MachineRegisterInfo(*TM->getRegisterInfo());
+ RegInfo = &CurMF->getRegInfo();
// Get our Loop information...
LI = &getAnalysis<MachineLoopInfo>();
VisitAllLoops(CurLoop);
}
- delete RegInfo;
return Changed;
}
/// 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, 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.getInstrDescriptor()->ImplicitUses) {
+ if (I.getDesc().getImplicitUses()) {
DOUT << " * Instruction has implicit uses:\n";
- const MRegisterInfo *MRI = TM->getRegisterInfo();
- const unsigned *ImpUses = I.getInstrDescriptor()->ImplicitUses;
-
- for (; *ImpUses; ++ImpUses)
- DOUT << " -> " << MRI->getName(*ImpUses) << "\n";
+ const TargetRegisterInfo *TRI = TM->getRegisterInfo();
+ for (const unsigned *ImpUses = I.getDesc().getImplicitUses();
+ *ImpUses; ++ImpUses)
+ DOUT << " -> " << TRI->getName(*ImpUses) << "\n";
}
- if (I.getInstrDescriptor()->ImplicitDefs) {
+ if (I.getDesc().getImplicitDefs()) {
DOUT << " * Instruction has implicit defines:\n";
- const MRegisterInfo *MRI = TM->getRegisterInfo();
- const unsigned *ImpDefs = I.getInstrDescriptor()->ImplicitDefs;
-
- for (; *ImpDefs; ++ImpDefs)
- DOUT << " -> " << MRI->getName(*ImpDefs) << "\n";
+ const TargetRegisterInfo *TRI = TM->getRegisterInfo();
+ for (const unsigned *ImpDefs = I.getDesc().getImplicitDefs();
+ *ImpDefs; ++ImpDefs)
+ DOUT << " -> " << TRI->getName(*ImpDefs) << "\n";
}
- if (TII->hasUnmodelledSideEffects(&I))
- DOUT << " * Instruction has side effects.\n";
+ //if (TII->hasUnmodelledSideEffects(&I))
+ //DOUT << " * Instruction has side effects.\n";
});
// The instruction is loop invariant if all of its operands are loop-invariant
unsigned Reg = MO.getReg();
// Don't hoist instructions that access physical registers.
- if (!MRegisterInfo::isVirtualRegister(Reg))
+ if (!TargetRegisterInfo::isVirtualRegister(Reg))
return false;
assert(RegInfo->getVRegDef(Reg)&&"Machine instr not mapped for this vreg?");
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;
}