// v1 = bitcast v0
// = v0
//
+// - Optimize Loads:
+//
+// Loads that can be folded into a later instruction. A load is foldable
+// if it loads to virtual registers and the virtual register defined has
+// a single use.
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "peephole-opt"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/ADT/Statistic.h"
using namespace llvm;
// Optimize Extensions
}
bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
+ DEBUG(dbgs() << "********** PEEPHOLE OPTIMIZER **********\n");
+ DEBUG(dbgs() << "********** Function: " << MF.getName() << '\n');
+
if (DisablePeephole)
return false;
ImmDefMIs.clear();
FoldAsLoadDefReg = 0;
- bool First = true;
- MachineBasicBlock::iterator PMII;
for (MachineBasicBlock::iterator
MII = I->begin(), MIE = I->end(); MII != MIE; ) {
MachineInstr *MI = &*MII;
+ // We may be erasing MI below, increment MII now.
+ ++MII;
LocalMIs.insert(MI);
// If there exists an instruction which belongs to the following
MI->isKill() || MI->isInlineAsm() || MI->isDebugValue() ||
MI->hasUnmodeledSideEffects()) {
FoldAsLoadDefReg = 0;
- ++MII;
continue;
}
if (MI->mayStore() || MI->isCall())
// MI is deleted.
LocalMIs.erase(MI);
Changed = true;
- MII = First ? I->begin() : llvm::next(PMII);
continue;
}
SeenMoveImm = true;
} else {
Changed |= optimizeExtInstr(MI, MBB, LocalMIs);
+ // optimizeExtInstr might have created new instructions after MI
+ // and before the already incremented MII. Adjust MII so that the
+ // next iteration sees the new instructions.
+ MII = MI;
+ ++MII;
if (SeenMoveImm)
Changed |= foldImmediate(MI, MBB, ImmDefRegs, ImmDefMIs);
}
FoldAsLoadDefReg, DefMI);
if (FoldMI) {
// Update LocalMIs since we replaced MI with FoldMI and deleted DefMI.
+ DEBUG(dbgs() << "Replacing: " << *MI);
+ DEBUG(dbgs() << " With: " << *FoldMI);
LocalMIs.erase(MI);
LocalMIs.erase(DefMI);
LocalMIs.insert(FoldMI);
// MI is replaced with FoldMI.
Changed = true;
- PMII = FoldMI;
- MII = llvm::next(PMII);
continue;
}
}
- First = false;
- PMII = MII;
- ++MII;
}
}