+// Returns instruction preceding MBBI in MachineFunction.
+// If MBBI is the first instruction of the first basic block, returns null.
+static MachineBasicBlock::const_iterator
+PrevCrossBBInst(MachineBasicBlock::const_iterator MBBI) {
+ const MachineBasicBlock *MBB = MBBI->getParent();
+ while (MBBI == MBB->begin()) {
+ if (MBB == MBB->getParent()->begin())
+ return nullptr;
+ MBB = MBB->getPrevNode();
+ MBBI = MBB->end();
+ }
+ return --MBBI;
+}
+
+static const Constant *getConstantFromPool(const MachineInstr &MI,
+ const MachineOperand &Op) {
+ if (!Op.isCPI())
+ return nullptr;
+
+ ArrayRef<MachineConstantPoolEntry> Constants =
+ MI.getParent()->getParent()->getConstantPool()->getConstants();
+ const MachineConstantPoolEntry &ConstantEntry =
+ Constants[Op.getIndex()];
+
+ // Bail if this is a machine constant pool entry, we won't be able to dig out
+ // anything useful.
+ if (ConstantEntry.isMachineConstantPoolEntry())
+ return nullptr;
+
+ auto *C = dyn_cast<Constant>(ConstantEntry.Val.ConstVal);
+ assert((!C || ConstantEntry.getType() == C->getType()) &&
+ "Expected a constant of the same type!");
+ return C;
+}
+
+static std::string getShuffleComment(const MachineOperand &DstOp,
+ const MachineOperand &SrcOp,
+ ArrayRef<int> Mask) {
+ std::string Comment;
+
+ // Compute the name for a register. This is really goofy because we have
+ // multiple instruction printers that could (in theory) use different
+ // names. Fortunately most people use the ATT style (outside of Windows)
+ // and they actually agree on register naming here. Ultimately, this is
+ // a comment, and so its OK if it isn't perfect.
+ auto GetRegisterName = [](unsigned RegNum) -> StringRef {
+ return X86ATTInstPrinter::getRegisterName(RegNum);
+ };
+
+ StringRef DstName = DstOp.isReg() ? GetRegisterName(DstOp.getReg()) : "mem";
+ StringRef SrcName = SrcOp.isReg() ? GetRegisterName(SrcOp.getReg()) : "mem";
+
+ raw_string_ostream CS(Comment);
+ CS << DstName << " = ";
+ bool NeedComma = false;
+ bool InSrc = false;
+ for (int M : Mask) {
+ // Wrap up any prior entry...
+ if (M == SM_SentinelZero && InSrc) {
+ InSrc = false;
+ CS << "]";
+ }
+ if (NeedComma)
+ CS << ",";
+ else
+ NeedComma = true;
+
+ // Print this shuffle...
+ if (M == SM_SentinelZero) {
+ CS << "zero";
+ } else {
+ if (!InSrc) {
+ InSrc = true;
+ CS << SrcName << "[";
+ }
+ if (M == SM_SentinelUndef)
+ CS << "u";
+ else
+ CS << M;
+ }
+ }
+ if (InSrc)
+ CS << "]";
+ CS.flush();
+
+ return Comment;
+}
+