Expand the sel pseudo/macro. This generates basic blocks where previously
there were inline br .+4 instructions. Soon everything can enjoy the
full instruction scheduling experience.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175718 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index e0080e6..5605759 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -55,6 +55,12 @@
cl::desc("MIPS: mips16 hard float enable."),
cl::init(false));
+static cl::opt<bool> DontExpandCondPseudos16(
+ "mips16-dont-expand-cond-pseudo",
+ cl::init(false),
+ cl::desc("Dont expand conditional move related "
+ "pseudos for Mips 16"),
+ cl::Hidden);
static const uint16_t O32IntRegs[4] = {
@@ -1230,11 +1236,74 @@
return Sink;
}
+MachineBasicBlock *MipsTargetLowering::EmitSel16(unsigned Opc, MachineInstr *MI,
+ MachineBasicBlock *BB) const {
+ if (DontExpandCondPseudos16)
+ return BB;
+ const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
+ DebugLoc dl = MI->getDebugLoc();
+ // To "insert" a SELECT_CC instruction, we actually have to insert the
+ // diamond control-flow pattern. The incoming instruction knows the
+ // destination vreg to set, the condition code register to branch on, the
+ // true/false values to select between, and a branch opcode to use.
+ const BasicBlock *LLVM_BB = BB->getBasicBlock();
+ MachineFunction::iterator It = BB;
+ ++It;
+
+ // thisMBB:
+ // ...
+ // TrueVal = ...
+ // setcc r1, r2, r3
+ // bNE r1, r0, copy1MBB
+ // fallthrough --> copy0MBB
+ MachineBasicBlock *thisMBB = BB;
+ MachineFunction *F = BB->getParent();
+ MachineBasicBlock *copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
+ MachineBasicBlock *sinkMBB = F->CreateMachineBasicBlock(LLVM_BB);
+ F->insert(It, copy0MBB);
+ F->insert(It, sinkMBB);
+
+ // Transfer the remainder of BB and its successor edges to sinkMBB.
+ sinkMBB->splice(sinkMBB->begin(), BB,
+ llvm::next(MachineBasicBlock::iterator(MI)),
+ BB->end());
+ sinkMBB->transferSuccessorsAndUpdatePHIs(BB);
+
+ // Next, add the true and fallthrough blocks as its successors.
+ BB->addSuccessor(copy0MBB);
+ BB->addSuccessor(sinkMBB);
+
+ BuildMI(BB, dl, TII->get(Opc)).addReg(MI->getOperand(3).getReg())
+ .addMBB(sinkMBB);
+
+ // copy0MBB:
+ // %FalseValue = ...
+ // # fallthrough to sinkMBB
+ BB = copy0MBB;
+
+ // Update machine-CFG edges
+ BB->addSuccessor(sinkMBB);
+
+ // sinkMBB:
+ // %Result = phi [ %TrueValue, thisMBB ], [ %FalseValue, copy0MBB ]
+ // ...
+ BB = sinkMBB;
+
+ BuildMI(*BB, BB->begin(), dl,
+ TII->get(Mips::PHI), MI->getOperand(0).getReg())
+ .addReg(MI->getOperand(1).getReg()).addMBB(thisMBB)
+ .addReg(MI->getOperand(2).getReg()).addMBB(copy0MBB);
+
+ MI->eraseFromParent(); // The pseudo instruction is gone now.
+ return BB;
+}
+
MachineBasicBlock *
MipsTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *BB) const {
switch (MI->getOpcode()) {
- default: llvm_unreachable("Unexpected instr type to insert");
+ default:
+ llvm_unreachable("Unexpected instr type to insert");
case Mips::ATOMIC_LOAD_ADD_I8:
case Mips::ATOMIC_LOAD_ADD_I8_P8:
return EmitAtomicBinaryPartword(MI, BB, 1, Mips::ADDu);
@@ -1340,6 +1409,10 @@
return EmitAtomicCmpSwap(MI, BB, 8);
case Mips::BPOSGE32_PSEUDO:
return EmitBPOSGE32(MI, BB);
+ case Mips::SelBeqZ:
+ return EmitSel16(Mips::BeqzRxImm16, MI, BB);
+ case Mips::SelBneZ:
+ return EmitSel16(Mips::BnezRxImm16, MI, BB);
}
}