//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "codegen-dce"
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
using namespace llvm;
+#define DEBUG_TYPE "codegen-dce"
+
STATISTIC(NumDeletes, "Number of dead instructions deleted");
namespace {
class DeadMachineInstructionElim : public MachineFunctionPass {
- virtual bool runOnMachineFunction(MachineFunction &MF);
+ bool runOnMachineFunction(MachineFunction &MF) override;
const TargetRegisterInfo *TRI;
const MachineRegisterInfo *MRI;
if (MI->isInlineAsm())
return false;
+ // Don't delete frame allocation labels.
+ if (MI->getOpcode() == TargetOpcode::FRAME_ALLOC)
+ return false;
+
// Don't delete instructions with side effects.
bool SawStore = false;
- if (!MI->isSafeToMove(TII, 0, SawStore) && !MI->isPHI())
+ if (!MI->isSafeToMove(TII, nullptr, SawStore) && !MI->isPHI())
return false;
// Examine each operand.
}
bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
+ if (skipOptnoneFunction(*MF.getFunction()))
+ return false;
+
bool AnyChanges = false;
MRI = &MF.getRegInfo();
- TRI = MF.getTarget().getRegisterInfo();
- TII = MF.getTarget().getInstrInfo();
+ TRI = MF.getSubtarget().getRegisterInfo();
+ TII = MF.getSubtarget().getInstrInfo();
// Loop over all instructions in all blocks, from bottom to top, so that it's
// more likely that chains of dependent but ultimately dead instructions will
if (isDead(MI)) {
DEBUG(dbgs() << "DeadMachineInstructionElim: DELETING: " << *MI);
// It is possible that some DBG_VALUE instructions refer to this
- // instruction. Examine each def operand for such references;
- // if found, mark the DBG_VALUE as undef (but don't delete it).
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- const MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg() || !MO.isDef())
- continue;
- unsigned Reg = MO.getReg();
- if (!TargetRegisterInfo::isVirtualRegister(Reg))
- continue;
- MachineRegisterInfo::use_iterator nextI;
- for (MachineRegisterInfo::use_iterator I = MRI->use_begin(Reg),
- E = MRI->use_end(); I!=E; I=nextI) {
- nextI = llvm::next(I); // I is invalidated by the setReg
- MachineOperand& Use = I.getOperand();
- MachineInstr *UseMI = Use.getParent();
- if (UseMI==MI)
- continue;
- assert(Use.isDebug());
- UseMI->getOperand(0).setReg(0U);
- }
- }
+ // instruction. They get marked as undef and will be deleted
+ // in the live debug variable analysis.
+ MI->eraseFromParentAndMarkDBGValuesForRemoval();
AnyChanges = true;
- MI->eraseFromParent();
++NumDeletes;
MIE = MBB->rend();
// MII is now pointing to the next instruction to process,