- case ARM::BR_JTr:
- case ARM::BR_JTm:
- case ARM::BR_JTadd:
- case ARM::tBR_JTr:
- case ARM::t2BR_JT:
- case ARM::t2TBB_JT:
- case ARM::t2TBH_JT: {
- // These are jumptable branches, i.e. a branch followed by an inlined
- // jumptable. The size is 4 + 4 * number of entries. For TBB, each
- // entry is one byte; TBH two byte each.
- unsigned EntrySize = (Opc == ARM::t2TBB_JT)
- ? 1 : ((Opc == ARM::t2TBH_JT) ? 2 : 4);
- unsigned NumOps = MCID.getNumOperands();
- MachineOperand JTOP =
- MI->getOperand(NumOps - (MI->isPredicable() ? 3 : 2));
- unsigned JTI = JTOP.getIndex();
- const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
- assert(MJTI != nullptr);
- const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
- assert(JTI < JT.size());
- // Thumb instructions are 2 byte aligned, but JT entries are 4 byte
- // 4 aligned. The assembler / linker may add 2 byte padding just before
- // the JT entries. The size does not include this padding; the
- // constant islands pass does separate bookkeeping for it.
- // FIXME: If we know the size of the function is less than (1 << 16) *2
- // bytes, we can use 16-bit entries instead. Then there won't be an
- // alignment issue.
- unsigned InstSize = (Opc == ARM::tBR_JTr || Opc == ARM::t2BR_JT) ? 2 : 4;
- unsigned NumEntries = JT[JTI].MBBs.size();
- if (Opc == ARM::t2TBB_JT && (NumEntries & 1))
- // Make sure the instruction that follows TBB is 2-byte aligned.
- // FIXME: Constant island pass should insert an "ALIGN" instruction
- // instead.
- ++NumEntries;
- return NumEntries * EntrySize + InstSize;
- }