Allow target to place 2-address pass inserted copies in better spots. Thumb2 will use this to try to avoid breaking up IT blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105745 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/Thumb2InstrInfo.cpp b/lib/Target/ARM/Thumb2InstrInfo.cpp
index 280fd3e..8c19b9f 100644
--- a/lib/Target/ARM/Thumb2InstrInfo.cpp
+++ b/lib/Target/ARM/Thumb2InstrInfo.cpp
@@ -503,3 +503,46 @@
Offset = (isSub) ? -Offset : Offset;
return Offset == 0;
}
+
+/// scheduleTwoAddrSource - Schedule the copy / re-mat of the source of the
+/// two-addrss instruction inserted by two-address pass.
+void
+Thumb2InstrInfo::scheduleTwoAddrSource(MachineInstr *SrcMI,
+ MachineInstr *UseMI,
+ const TargetRegisterInfo &TRI) const {
+ if (SrcMI->getOpcode() != ARM::tMOVgpr2gpr ||
+ SrcMI->getOperand(1).isKill())
+ return;
+
+ unsigned PredReg = 0;
+ ARMCC::CondCodes CC = llvm::getInstrPredicate(UseMI, PredReg);
+ if (CC == ARMCC::AL || PredReg != ARM::CPSR)
+ return;
+
+ // Schedule the copy so it doesn't come between previous instructions
+ // and UseMI which can form an IT block.
+ unsigned SrcReg = SrcMI->getOperand(1).getReg();
+ ARMCC::CondCodes OCC = ARMCC::getOppositeCondition(CC);
+ MachineBasicBlock *MBB = UseMI->getParent();
+ MachineBasicBlock::iterator MBBI = SrcMI;
+ unsigned NumInsts = 0;
+ while (--MBBI != MBB->begin()) {
+ if (MBBI->isDebugValue())
+ continue;
+
+ MachineInstr *NMI = &*MBBI;
+ ARMCC::CondCodes NCC = llvm::getInstrPredicate(NMI, PredReg);
+ if (!(NCC == CC || NCC == OCC) ||
+ NMI->modifiesRegister(SrcReg, &TRI) ||
+ NMI->definesRegister(ARM::CPSR))
+ break;
+ if (++NumInsts == 4)
+ // Too many in a row!
+ return;
+ }
+
+ if (NumInsts) {
+ MBB->remove(SrcMI);
+ MBB->insert(++MBBI, SrcMI);
+ }
+}