[x86_64] Unimplemented Backend Features

This issue tracks Mu specification coverage in x86_64 backend.

Types:

• int<n>:
• n = 1 (some arithmetic)
• * n <= 64 and n != 8, 16, 32, or 64
• * n = 128, floating point conversions
• n > 64 and n != 128
• struct SSA variables
• hybrid SSA variables
• array SSA variables
• tagref64
• threadref
• `stackref``
• framecursorref
• irbuilderref
• vector<t n>

Instruction Clauses:

• keep Alive Clauses
• Exception clauses
• CALL
• binop (divison by zero)
• NEW/NEYHYBRID (allocation failure)
• LOAD/STORE/CMPXCHG (null referenced)
• CCALL (implementation defined)

Instructions:

• TAILCALL
• For unimplemented types:
  • EXTRACTVALUE/INSERTVALUE
  • EXTRACTELEMENT/INSERTELEMENT
  • SHUFFLEVECTOR
• Memory
• ALLOCA/ALLOCAHYBRID
• * CMPXCHG
• * FENCE
• ATOMICRMW
• Traps/watchpoints
• TRAP
• WATCHPOINT
• WPBRANCH
• Thread/stack instructions
• NEWTHREAD
• SWAPTSTACK

Common Instructions

• thread and stack things:
• current_stack
• thread_exit
• new_stack
• tr64.*
• futex.*
• kill_dependency
• native.* (except nativ.pin and nativ.unpnin)
• meta.*
• irbuilder.*