[llvm-commits] [llvm] r80733 - /llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp
Bob Wilson
bob.wilson at apple.com
Tue Sep 1 15:51:08 PDT 2009
Author: bwilson
Date: Tue Sep 1 17:51:08 2009
New Revision: 80733
URL: http://llvm.org/viewvc/llvm-project?rev=80733&view=rev
Log:
Refactor some code into separate functions. No functional changes.
Modified:
llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp
Modified: llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp?rev=80733&r1=80732&r2=80733&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp (original)
+++ llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp Tue Sep 1 17:51:08 2009
@@ -106,6 +106,15 @@
MachineFunction::iterator &mbbi,
unsigned RegB, unsigned Dist);
+ typedef std::pair<std::pair<unsigned, bool>, MachineInstr*> NewKill;
+ bool canUpdateDeletedKills(SmallVector<unsigned, 4> &Kills,
+ SmallVector<NewKill, 4> &NewKills,
+ MachineBasicBlock *MBB, unsigned Dist);
+ bool DeleteUnusedInstr(MachineBasicBlock::iterator &mi,
+ MachineBasicBlock::iterator &nmi,
+ MachineFunction::iterator &mbbi,
+ unsigned regB, unsigned regBIdx, unsigned Dist);
+
void ProcessCopy(MachineInstr *MI, MachineBasicBlock *MBB,
SmallPtrSet<MachineInstr*, 8> &Processed);
@@ -736,6 +745,75 @@
return true;
}
+/// canUpdateDeletedKills - Check if all the registers listed in Kills are
+/// killed by instructions in MBB preceding the current instruction at
+/// position Dist. If so, return true and record information about the
+/// preceding kills in NewKills.
+bool TwoAddressInstructionPass::
+canUpdateDeletedKills(SmallVector<unsigned, 4> &Kills,
+ SmallVector<NewKill, 4> &NewKills,
+ MachineBasicBlock *MBB, unsigned Dist) {
+ while (!Kills.empty()) {
+ unsigned Kill = Kills.back();
+ Kills.pop_back();
+ if (TargetRegisterInfo::isPhysicalRegister(Kill))
+ return false;
+
+ MachineInstr *LastKill = FindLastUseInMBB(Kill, MBB, Dist);
+ if (!LastKill)
+ return false;
+
+ bool isModRef = LastKill->modifiesRegister(Kill);
+ NewKills.push_back(std::make_pair(std::make_pair(Kill, isModRef),
+ LastKill));
+ }
+ return true;
+}
+
+/// DeleteUnusedInstr - If an instruction with a tied register operand can
+/// be safely deleted, just delete it.
+bool
+TwoAddressInstructionPass::DeleteUnusedInstr(MachineBasicBlock::iterator &mi,
+ MachineBasicBlock::iterator &nmi,
+ MachineFunction::iterator &mbbi,
+ unsigned regB, unsigned regBIdx,
+ unsigned Dist) {
+ // Check if the instruction has no side effects and if all its defs are dead.
+ SmallVector<unsigned, 4> Kills;
+ if (!isSafeToDelete(mi, regB, TII, Kills))
+ return false;
+
+ // If this instruction kills some virtual registers, we need to
+ // update the kill information. If it's not possible to do so,
+ // then bail out.
+ SmallVector<NewKill, 4> NewKills;
+ if (!canUpdateDeletedKills(Kills, NewKills, &*mbbi, Dist))
+ return false;
+
+ if (LV) {
+ while (!NewKills.empty()) {
+ MachineInstr *NewKill = NewKills.back().second;
+ unsigned Kill = NewKills.back().first.first;
+ bool isDead = NewKills.back().first.second;
+ NewKills.pop_back();
+ if (LV->removeVirtualRegisterKilled(Kill, mi)) {
+ if (isDead)
+ LV->addVirtualRegisterDead(Kill, NewKill);
+ else
+ LV->addVirtualRegisterKilled(Kill, NewKill);
+ }
+ }
+
+ // If regB was marked as a kill, update its Kills list.
+ if (mi->getOperand(regBIdx).isKill())
+ LV->removeVirtualRegisterKilled(regB, mi);
+ }
+
+ mbbi->erase(mi); // Nuke the old inst.
+ mi = nmi;
+ return true;
+}
+
/// runOnMachineFunction - Reduce two-address instructions to two operands.
///
bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
@@ -822,61 +900,13 @@
// allow us to coalesce A and B together, eliminating the copy we are
// about to insert.
if (!isKilled(*mi, regB, MRI, TII)) {
+
// If regA is dead and the instruction can be deleted, just delete
// it so it doesn't clobber regB.
- SmallVector<unsigned, 4> Kills;
if (mi->getOperand(ti).isDead() &&
- isSafeToDelete(mi, regB, TII, Kills)) {
- SmallVector<std::pair<std::pair<unsigned, bool>
- ,MachineInstr*>, 4> NewKills;
- bool ReallySafe = true;
- // If this instruction kills some virtual registers, we need
- // update the kill information. If it's not possible to do so,
- // then bail out.
- while (!Kills.empty()) {
- unsigned Kill = Kills.back();
- Kills.pop_back();
- if (TargetRegisterInfo::isPhysicalRegister(Kill)) {
- ReallySafe = false;
- break;
- }
- MachineInstr *LastKill = FindLastUseInMBB(Kill, &*mbbi, Dist);
- if (LastKill) {
- bool isModRef = LastKill->modifiesRegister(Kill);
- NewKills.push_back(std::make_pair(std::make_pair(Kill,isModRef),
- LastKill));
- } else {
- ReallySafe = false;
- break;
- }
- }
-
- if (ReallySafe) {
- if (LV) {
- while (!NewKills.empty()) {
- MachineInstr *NewKill = NewKills.back().second;
- unsigned Kill = NewKills.back().first.first;
- bool isDead = NewKills.back().first.second;
- NewKills.pop_back();
- if (LV->removeVirtualRegisterKilled(Kill, mi)) {
- if (isDead)
- LV->addVirtualRegisterDead(Kill, NewKill);
- else
- LV->addVirtualRegisterKilled(Kill, NewKill);
- }
- }
-
- // We're really going to nuke the old inst. If regB was marked
- // as a kill we need to update its Kills list.
- if (mi->getOperand(si).isKill())
- LV->removeVirtualRegisterKilled(regB, mi);
- }
-
- mbbi->erase(mi); // Nuke the old inst.
- mi = nmi;
- ++NumDeletes;
- break; // Done with this instruction.
- }
+ DeleteUnusedInstr(mi, nmi, mbbi, regB, si, Dist)) {
+ ++NumDeletes;
+ break; // Done with this instruction.
}
// If this instruction is commutative, check to see if C dies. If
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