//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "codegen-cp"
#include "llvm/CodeGen/Passes.h"
-#include "llvm/Pass.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
using namespace llvm;
+#define DEBUG_TYPE "codegen-cp"
+
STATISTIC(NumDeletes, "Number of dead copies deleted");
namespace {
initializeMachineCopyPropagationPass(*PassRegistry::getPassRegistry());
}
- virtual bool runOnMachineFunction(MachineFunction &MF);
+ bool runOnMachineFunction(MachineFunction &MF) override;
private:
typedef SmallVector<unsigned, 4> DestList;
SourceMap &SrcMap,
DenseMap<unsigned, MachineInstr*> &AvailCopyMap);
bool CopyPropagateBlock(MachineBasicBlock &MBB);
- void removeCopy(MachineInstr *MI);
};
}
char MachineCopyPropagation::ID = 0;
I != E; ++I) {
unsigned MappedDef = *I;
// Source of copy is no longer available for propagation.
- if (AvailCopyMap.erase(MappedDef)) {
- for (MCSubRegIterator SR(MappedDef, TRI); SR.isValid(); ++SR)
- AvailCopyMap.erase(*SR);
- }
+ AvailCopyMap.erase(MappedDef);
+ for (MCSubRegIterator SR(MappedDef, TRI); SR.isValid(); ++SR)
+ AvailCopyMap.erase(*SR);
}
}
}
return false;
}
-// Remove MI from the function because it has been determined it is dead.
-// Turn it into a noop KILL instruction if it has super-register liveness
-// adjustments.
-void MachineCopyPropagation::removeCopy(MachineInstr *MI) {
- if (MI->getNumOperands() == 2)
- MI->eraseFromParent();
- else
- MI->setDesc(TII->get(TargetOpcode::KILL));
-}
-
bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
SmallSetVector<MachineInstr*, 8> MaybeDeadCopies; // Candidates for deletion
DenseMap<unsigned, MachineInstr*> AvailCopyMap; // Def -> available copies map
DenseMap<unsigned, MachineInstr*> CopyMap; // Def -> copies map
SourceMap SrcMap; // Src -> Def map
+ DEBUG(dbgs() << "MCP: CopyPropagateBlock " << MBB.getName() << "\n");
+
bool Changed = false;
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ) {
MachineInstr *MI = &*I;
// CALL
// %RAX<def> = COPY %RSP
+ DEBUG(dbgs() << "MCP: copy is a NOP, removing: "; MI->dump());
+
// Clear any kills of Def between CopyMI and MI. This extends the
// live range.
for (MachineBasicBlock::iterator I = CopyMI, E = MI; I != E; ++I)
I->clearRegisterKills(Def, TRI);
- removeCopy(MI);
+ MI->eraseFromParent();
Changed = true;
++NumDeletes;
continue;
// If Src is defined by a previous copy, it cannot be eliminated.
for (MCRegAliasIterator AI(Src, TRI, true); AI.isValid(); ++AI) {
CI = CopyMap.find(*AI);
- if (CI != CopyMap.end())
+ if (CI != CopyMap.end()) {
+ DEBUG(dbgs() << "MCP: Copy is no longer dead: "; CI->second->dump());
MaybeDeadCopies.remove(CI->second);
+ }
}
+ DEBUG(dbgs() << "MCP: Copy is a deletion candidate: "; MI->dump());
+
// Copy is now a candidate for deletion.
MaybeDeadCopies.insert(MI);
CopyMap.erase(*AI);
AvailCopyMap.erase(*AI);
}
- CopyMap[Def] = MI;
- AvailCopyMap[Def] = MI;
- for (MCSubRegIterator SR(Def, TRI); SR.isValid(); ++SR) {
+ for (MCSubRegIterator SR(Def, TRI, /*IncludeSelf=*/true); SR.isValid();
+ ++SR) {
CopyMap[*SR] = MI;
AvailCopyMap[*SR] = MI;
}
// for elimination.
for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
DenseMap<unsigned, MachineInstr*>::iterator CI = CopyMap.find(*AI);
- if (CI != CopyMap.end())
+ if (CI != CopyMap.end()) {
+ DEBUG(dbgs() << "MCP: Copy is used - not dead: "; CI->second->dump());
MaybeDeadCopies.remove(CI->second);
+ }
}
+ // Treat undef use like defs for copy propagation but not for
+ // dead copy. We would need to do a liveness check to be sure the copy
+ // is dead for undef uses.
+ // The backends are allowed to do whatever they want with undef value
+ // and we cannot be sure this register will not be rewritten to break
+ // some false dependencies for the hardware for instance.
+ if (MO.isUndef())
+ Defs.push_back(Reg);
}
// The instruction has a register mask operand which means that it clobbers
unsigned Reg = (*DI)->getOperand(0).getReg();
if (MRI->isReserved(Reg) || !MaskMO.clobbersPhysReg(Reg))
continue;
- removeCopy(*DI);
+ DEBUG(dbgs() << "MCP: Removing copy due to regmask clobbering: ";
+ (*DI)->dump());
+ (*DI)->eraseFromParent();
Changed = true;
++NumDeletes;
}
DI = MaybeDeadCopies.begin(), DE = MaybeDeadCopies.end();
DI != DE; ++DI) {
if (!MRI->isReserved((*DI)->getOperand(0).getReg())) {
- removeCopy(*DI);
+ (*DI)->eraseFromParent();
Changed = true;
++NumDeletes;
}
}
bool MachineCopyPropagation::runOnMachineFunction(MachineFunction &MF) {
+ if (skipOptnoneFunction(*MF.getFunction()))
+ return false;
+
bool Changed = false;
- TRI = MF.getTarget().getRegisterInfo();
- TII = MF.getTarget().getInstrInfo();
+ TRI = MF.getSubtarget().getRegisterInfo();
+ TII = MF.getSubtarget().getInstrInfo();
MRI = &MF.getRegInfo();
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
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