Add bunch of branch folding stuff
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76055 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/SystemZ/SystemZInstrInfo.cpp b/lib/Target/SystemZ/SystemZInstrInfo.cpp
index d22e643..e5a7fd4 100644
--- a/lib/Target/SystemZ/SystemZInstrInfo.cpp
+++ b/lib/Target/SystemZ/SystemZInstrInfo.cpp
@@ -309,6 +309,137 @@
return true;
}
+bool SystemZInstrInfo::
+ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
+ assert(Cond.size() == 1 && "Invalid Xbranch condition!");
+
+ SystemZCC::CondCodes CC = static_cast<SystemZCC::CondCodes>(Cond[0].getImm());
+ Cond[0].setImm(getOppositeCondition(CC));
+ return false;
+}
+
+bool SystemZInstrInfo::BlockHasNoFallThrough(const MachineBasicBlock &MBB)const{
+ if (MBB.empty()) return false;
+
+ switch (MBB.back().getOpcode()) {
+ case SystemZ::RET: // Return.
+ case SystemZ::JMP: // Uncond branch.
+ case SystemZ::JMPr: // Indirect branch.
+ return true;
+ default: return false;
+ }
+}
+
+bool SystemZInstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
+ const TargetInstrDesc &TID = MI->getDesc();
+ if (!TID.isTerminator()) return false;
+
+ // Conditional branch is a special case.
+ if (TID.isBranch() && !TID.isBarrier())
+ return true;
+ if (!TID.isPredicable())
+ return true;
+ return !isPredicated(MI);
+}
+
+bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
+ MachineBasicBlock *&TBB,
+ MachineBasicBlock *&FBB,
+ SmallVectorImpl<MachineOperand> &Cond,
+ bool AllowModify) const {
+ // Start from the bottom of the block and work up, examining the
+ // terminator instructions.
+ MachineBasicBlock::iterator I = MBB.end();
+ while (I != MBB.begin()) {
+ --I;
+ // Working from the bottom, when we see a non-terminator
+ // instruction, we're done.
+ if (!isUnpredicatedTerminator(I))
+ break;
+
+ // A terminator that isn't a branch can't easily be handled
+ // by this analysis.
+ if (!I->getDesc().isBranch())
+ return true;
+
+ // Handle unconditional branches.
+ if (I->getOpcode() == SystemZ::JMP) {
+ if (!AllowModify) {
+ TBB = I->getOperand(0).getMBB();
+ continue;
+ }
+
+ // If the block has any instructions after a JMP, delete them.
+ while (next(I) != MBB.end())
+ next(I)->eraseFromParent();
+ Cond.clear();
+ FBB = 0;
+
+ // Delete the JMP if it's equivalent to a fall-through.
+ if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
+ TBB = 0;
+ I->eraseFromParent();
+ I = MBB.end();
+ continue;
+ }
+
+ // TBB is used to indicate the unconditinal destination.
+ TBB = I->getOperand(0).getMBB();
+ continue;
+ }
+
+ // Handle conditional branches.
+ SystemZCC::CondCodes BranchCode = getCondFromBranchOpc(I->getOpcode());
+ if (BranchCode == SystemZCC::INVALID)
+ return true; // Can't handle indirect branch.
+
+ // Working from the bottom, handle the first conditional branch.
+ if (Cond.empty()) {
+ FBB = TBB;
+ TBB = I->getOperand(0).getMBB();
+ Cond.push_back(MachineOperand::CreateImm(BranchCode));
+ continue;
+ }
+
+ // Handle subsequent conditional branches. Only handle the case where all
+ // conditional branches branch to the same destination.
+ assert(Cond.size() == 1);
+ assert(TBB);
+
+ // Only handle the case where all conditional branches branch to
+ // the same destination.
+ if (TBB != I->getOperand(0).getMBB())
+ return true;
+
+ SystemZCC::CondCodes OldBranchCode = (SystemZCC::CondCodes)Cond[0].getImm();
+ // If the conditions are the same, we can leave them alone.
+ if (OldBranchCode == BranchCode)
+ continue;
+
+ return true;
+ }
+
+ return false;
+}
+
+unsigned SystemZInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
+ MachineBasicBlock::iterator I = MBB.end();
+ unsigned Count = 0;
+
+ while (I != MBB.begin()) {
+ --I;
+ if (I->getOpcode() != SystemZ::JMP &&
+ getCondFromBranchOpc(I->getOpcode()) == SystemZCC::INVALID)
+ break;
+ // Remove the branch.
+ I->eraseFromParent();
+ I = MBB.end();
+ ++Count;
+ }
+
+ return Count;
+}
+
unsigned
SystemZInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
@@ -363,6 +494,49 @@
}
}
+SystemZCC::CondCodes
+SystemZInstrInfo::getCondFromBranchOpc(unsigned Opc) const {
+ switch (Opc) {
+ default: return SystemZCC::INVALID;
+ case SystemZ::JO: return SystemZCC::O;
+ case SystemZ::JH: return SystemZCC::H;
+ case SystemZ::JNLE: return SystemZCC::NLE;
+ case SystemZ::JL: return SystemZCC::L;
+ case SystemZ::JNHE: return SystemZCC::NHE;
+ case SystemZ::JLH: return SystemZCC::LH;
+ case SystemZ::JNE: return SystemZCC::NE;
+ case SystemZ::JE: return SystemZCC::E;
+ case SystemZ::JNLH: return SystemZCC::NLH;
+ case SystemZ::JHE: return SystemZCC::HE;
+ case SystemZ::JNL: return SystemZCC::NL;
+ case SystemZ::JLE: return SystemZCC::LE;
+ case SystemZ::JNH: return SystemZCC::NH;
+ case SystemZ::JNO: return SystemZCC::NO;
+ }
+}
+
+SystemZCC::CondCodes
+SystemZInstrInfo::getOppositeCondition(SystemZCC::CondCodes CC) const {
+ switch (CC) {
+ default:
+ assert(0 && "Invalid condition!");
+ case SystemZCC::O: return SystemZCC::NO;
+ case SystemZCC::H: return SystemZCC::NH;
+ case SystemZCC::NLE: return SystemZCC::LE;
+ case SystemZCC::L: return SystemZCC::NL;
+ case SystemZCC::NHE: return SystemZCC::HE;
+ case SystemZCC::LH: return SystemZCC::NLH;
+ case SystemZCC::NE: return SystemZCC::E;
+ case SystemZCC::E: return SystemZCC::NE;
+ case SystemZCC::NLH: return SystemZCC::LH;
+ case SystemZCC::HE: return SystemZCC::NHE;
+ case SystemZCC::NL: return SystemZCC::L;
+ case SystemZCC::LE: return SystemZCC::NLE;
+ case SystemZCC::NH: return SystemZCC::H;
+ case SystemZCC::NO: return SystemZCC::O;
+ }
+}
+
const TargetInstrDesc&
SystemZInstrInfo::getLongDispOpc(unsigned Opc) const {
switch (Opc) {