Enable two-address remat by default.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52701 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 0d71589..54adc96 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -53,10 +53,6 @@
STATISTIC(Num3AddrSunk, "Number of 3-address instructions sunk");
STATISTIC(NumReMats, "Number of instructions re-materialized");
-static cl::opt<bool>
-EnableReMat("two-addr-remat", cl::init(false), cl::Hidden,
- cl::desc("Two-addr conversion should remat when possible."));
-
namespace {
class VISIBILITY_HIDDEN TwoAddressInstructionPass
: public MachineFunctionPass {
@@ -71,8 +67,8 @@
bool isSafeToReMat(unsigned DstReg, MachineInstr *MI);
bool isProfitableToReMat(unsigned Reg, const TargetRegisterClass *RC,
- MachineInstr *MI, unsigned Loc,
- MachineInstr *DefMI, MachineBasicBlock *MBB,
+ MachineInstr *MI, MachineInstr *DefMI,
+ MachineBasicBlock *MBB, unsigned Loc,
DenseMap<MachineInstr*, unsigned> &DistanceMap);
public:
static char ID; // Pass identification, replacement for typeid
@@ -248,12 +244,9 @@
bool
TwoAddressInstructionPass::isProfitableToReMat(unsigned Reg,
const TargetRegisterClass *RC,
- MachineInstr *MI, unsigned Loc,
- MachineInstr *DefMI, MachineBasicBlock *MBB,
- DenseMap<MachineInstr*, unsigned> &DistanceMap) {
- if (DefMI->getParent() != MBB)
- return true;
- // If earlier uses in MBB are not two-address uses, then don't remat.
+ MachineInstr *MI, MachineInstr *DefMI,
+ MachineBasicBlock *MBB, unsigned Loc,
+ DenseMap<MachineInstr*, unsigned> &DistanceMap){
bool OtherUse = false;
for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg),
UE = MRI->use_end(); UI != UE; ++UI) {
@@ -261,18 +254,26 @@
if (!UseMO.isUse())
continue;
MachineInstr *UseMI = UseMO.getParent();
- if (UseMI->getParent() != MBB)
- continue;
- DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
- if (DI != DistanceMap.end() && DI->second == Loc)
- continue; // Current use.
- OtherUse = true;
- // There is at least one other use in the MBB that will clobber the
- // register.
- if (isTwoAddrUse(UseMI, Reg))
- return true;
+ MachineBasicBlock *UseMBB = UseMI->getParent();
+ if (UseMBB == MBB) {
+ DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
+ if (DI != DistanceMap.end() && DI->second == Loc)
+ continue; // Current use.
+ OtherUse = true;
+ // There is at least one other use in the MBB that will clobber the
+ // register.
+ if (isTwoAddrUse(UseMI, Reg))
+ return true;
+ }
}
- return !OtherUse;
+
+ // If other uses in MBB are not two-address uses, then don't remat.
+ if (OtherUse)
+ return false;
+
+ // No other uses in the same block, remat if it's defined in the same
+ // block so it does not unnecessarily extend the live range.
+ return MBB == DefMI->getParent();
}
/// runOnMachineFunction - Reduce two-address instructions to two operands.
@@ -428,9 +429,9 @@
MachineInstr *DefMI = MRI->getVRegDef(regB);
// If it's safe and profitable, remat the definition instead of
// copying it.
- if (EnableReMat && DefMI &&
+ if (DefMI &&
isSafeToReMat(regB, DefMI) &&
- isProfitableToReMat(regB, rc, mi, Dist, DefMI, mbbi,DistanceMap)){
+ isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist,DistanceMap)){
DEBUG(cerr << "2addr: REMATTING : " << *DefMI << "\n");
TII->reMaterialize(*mbbi, mi, regA, DefMI);
ReMatRegs.set(regB);
@@ -473,17 +474,14 @@
}
}
- if (EnableReMat) {
- // Some remat'ed instructions are dead.
- int VReg = ReMatRegs.find_first();
- while (VReg != -1) {
- if (MRI->use_empty(VReg)) {
- MachineInstr *DefMI = MRI->getVRegDef(VReg);
- DefMI->eraseFromParent();
- }
- VReg = ReMatRegs.find_next(VReg);
+ // Some remat'ed instructions are dead.
+ int VReg = ReMatRegs.find_first();
+ while (VReg != -1) {
+ if (MRI->use_empty(VReg)) {
+ MachineInstr *DefMI = MRI->getVRegDef(VReg);
+ DefMI->eraseFromParent();
}
-
+ VReg = ReMatRegs.find_next(VReg);
}
return MadeChange;