First cut trivial re-materialization support.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35208 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 9a1e58f..dfa5e43 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -35,6 +35,7 @@
using namespace llvm;
STATISTIC(NumSpills, "Number of register spills");
+STATISTIC(NumReMats, "Number of re-materialization");
STATISTIC(NumStores, "Number of stores added");
STATISTIC(NumLoads , "Number of loads added");
STATISTIC(NumReused, "Number of values reused");
@@ -60,7 +61,8 @@
VirtRegMap::VirtRegMap(MachineFunction &mf)
: TII(*mf.getTarget().getInstrInfo()), MF(mf),
- Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT) {
+ Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT),
+ ReMatId(MAX_STACK_SLOT+1) {
grow();
}
@@ -88,6 +90,15 @@
Virt2StackSlotMap[virtReg] = frameIndex;
}
+int VirtRegMap::assignVirtReMatId(unsigned virtReg) {
+ assert(MRegisterInfo::isVirtualRegister(virtReg));
+ assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
+ "attempt to assign re-mat id to already spilled register");
+ Virt2StackSlotMap[virtReg] = ReMatId;
+ ++NumReMats;
+ return ReMatId++;
+}
+
void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
unsigned OpNo, MachineInstr *NewMI) {
// Move previous memory references folded to new instruction.
@@ -227,13 +238,17 @@
DOUT << "\n**** Local spiller rewriting function '"
<< MF.getFunction()->getName() << "':\n";
+ std::vector<MachineInstr *> ReMatedMIs;
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
MBB != E; ++MBB)
- RewriteMBB(*MBB, VRM);
+ RewriteMBB(*MBB, VRM, ReMatedMIs);
+ for (unsigned i = 0, e = ReMatedMIs.size(); i != e; ++i)
+ delete ReMatedMIs[i];
return true;
}
private:
- void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM);
+ void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
+ std::vector<MachineInstr*> &ReMatedMIs);
};
}
@@ -338,8 +353,11 @@
SpillSlotsAvailable[Slot] =
std::make_pair((Reg << 1) | (unsigned)CanClobber, DefUses);
- DOUT << "Remembering SS#" << Slot << " in physreg "
- << MRI->getName(Reg) << "\n";
+ if (Slot > VirtRegMap::MAX_STACK_SLOT)
+ DOUT << "Remembering RM#" << Slot-VirtRegMap::MAX_STACK_SLOT-1;
+ else
+ DOUT << "Remembering SS#" << Slot;
+ DOUT << " in physreg " << MRI->getName(Reg) << "\n";
}
/// canClobberPhysReg - Return true if the spiller is allowed to change the
@@ -405,7 +423,11 @@
"Bidirectional map mismatch!");
SpillSlotsAvailable.erase(Slot);
DOUT << "PhysReg " << MRI->getName(PhysReg)
- << " clobbered, invalidating SS#" << Slot << "\n";
+ << " clobbered, invalidating ";
+ if (Slot > VirtRegMap::MAX_STACK_SLOT)
+ DOUT << "RM#" << Slot-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
+ else
+ DOUT << "SS#" << Slot << "\n";
}
}
@@ -599,7 +621,8 @@
/// rewriteMBB - Keep track of which spills are available even after the
/// register allocator is done with them. If possible, avoid reloading vregs.
-void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
+void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
+ std::vector<MachineInstr*> &ReMatedMIs) {
DOUT << MBB.getBasicBlock()->getName() << ":\n";
@@ -629,6 +652,27 @@
// Loop over all of the implicit defs, clearing them from our available
// sets.
const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
+
+ // If this instruction is being rematerialized, just remove it!
+ if (TID->Flags & M_REMATERIALIZIBLE) {
+ bool Remove = true;
+ for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI.getOperand(i);
+ if (!MO.isRegister() || MO.getReg() == 0)
+ continue; // Ignore non-register operands.
+ if (MO.isDef() && !VRM.isReMaterialized(MO.getReg())) {
+ Remove = false;
+ break;
+ }
+ }
+ if (Remove) {
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ ReMatedMIs.push_back(MI.removeFromParent());
+ MII = NextMII;
+ continue;
+ }
+ }
+
const unsigned *ImpDef = TID->ImplicitDefs;
if (ImpDef) {
for ( ; *ImpDef; ++ImpDef) {
@@ -670,6 +714,7 @@
if (!MO.isUse())
continue; // Handle defs in the loop below (handle use&def here though)
+ bool doReMat = VRM.isReMaterialized(VirtReg);
int StackSlot = VRM.getStackSlot(VirtReg);
unsigned PhysReg;
@@ -695,7 +740,11 @@
if (CanReuse) {
// If this stack slot value is already available, reuse it!
- DOUT << "Reusing SS#" << StackSlot << " from physreg "
+ if (StackSlot > VirtRegMap::MAX_STACK_SLOT)
+ DOUT << "Reusing RM#" << StackSlot-VirtRegMap::MAX_STACK_SLOT-1;
+ else
+ DOUT << "Reusing SS#" << StackSlot;
+ DOUT << " from physreg "
<< MRI->getName(PhysReg) << " for vreg"
<< VirtReg <<" instead of reloading into physreg "
<< MRI->getName(VRM.getPhys(VirtReg)) << "\n";
@@ -767,8 +816,11 @@
// incoming, we don't need to inserted a dead copy.
if (DesignatedReg == PhysReg) {
// If this stack slot value is already available, reuse it!
- DOUT << "Reusing SS#" << StackSlot << " from physreg "
- << MRI->getName(PhysReg) << " for vreg"
+ if (StackSlot > VirtRegMap::MAX_STACK_SLOT)
+ DOUT << "Reusing RM#" << StackSlot-VirtRegMap::MAX_STACK_SLOT-1;
+ else
+ DOUT << "Reusing SS#" << StackSlot;
+ DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg"
<< VirtReg
<< " instead of reloading into same physreg.\n";
MI.getOperand(i).setReg(PhysReg);
@@ -828,12 +880,16 @@
PhysRegsUsed[PhysReg] = true;
ReusedOperands.markClobbered(PhysReg);
- MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
+ if (doReMat)
+ MRI->reMaterialize(MBB, &MI, PhysReg, VRM.getReMaterializedMI(VirtReg));
+ else
+ MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
// This invalidates PhysReg.
Spills.ClobberPhysReg(PhysReg);
// Any stores to this stack slot are not dead anymore.
- MaybeDeadStores.erase(StackSlot);
+ if (!doReMat)
+ MaybeDeadStores.erase(StackSlot);
Spills.addAvailable(StackSlot, &MI, PhysReg);
// Assumes this is the last use. IsKill will be unset if reg is reused
// unless it's a two-address operand.