1. Move new ISD node definitions to TableGen.
2. Instruction selection done in TableGen using patterns.

1. Update summary to have a better explanation of this patch.
2. Add a post-ISel hook to add register allocation hints to LDRD/STRD operands.
3. In the AArch32 case, move ISel from TableGen back to the C++ side. This is needed because we must have a custom lowering whenever LDRD/STRD selection would normally yield a register offset. The ARM Load/Store Optimizer is not able to handle LDRD/STRD's register offsets in the cases where LDRD/STRD must be reverted to LDM/STM. As such, the C++ instruction selection opts for not generating instructions with a register offset.
4. Improve test by testing several immediate boundary cases.

Require single-precision floating-point registers instead.

Now using a pseudo instruction instead, VMOVHcc, which is lowered into a single-precision VMOV.

Fixed the immediate range check to cover -1020 to 1020.

1. Move the custom SD nodes to TableGen.
2. Truncating stores not restricted anymore.
3. Remove isUnindexed() calls since they should return true always at this point.
4. Extend test to also check loads/stores that have an offset.

1. Create new AArch64ISD nodes specific to load/store of pairs of registers.
2. Custom lower i128 volatile loads/stores to these new AArch64ISD nodes.

1. Not exclude extloads anymore.
2. Create new ARMISD nodes specific to load/store of dual registers.
3. Custom lower i64 volatile loads/stores to these new ARMISD nodes.

Amending patch to include the transfer of memory operands from the original
SDNode to the new MachineSDNode.

Added support for __clsll as requested.

Add support for __clsll.

Use __builtin_bit_cast to perform the relevant bitcasts.

Run clang-format

Added test into Disassembler

Yes, thanks.

Moved trace call inside the critical section.

Yes, thanks.

Fixed indentation and variable name issues.

Applied your comments.

Ok, I'm fixing the patch. Thanks.

Okay. Thanks for the clarification. Should I create another patch just for the removal of lines 223-225?

Yes, please.

Done.

Given that checking 'tasking_ser' is redundant, I removed it.

Yes, thanks.

I have applied the suggestions.

Yes, please. Thanks.

Yes, please.