SEM BodyInfo | Info
  instructions.location    = 0
  instructions.revLocation = 0

-- Thread location information through the AST
ATTR Instructions Instruction CaseOffsets [ | location : Int | ]
SEM Instruction | Location  lhs.location = @index

-- Thread location information backward through the AST
ATTR Instructions Instruction CaseOffsets [ | revLocation : Int | ]
SEM Instruction | Location  lhs.revLocation = @index
SEM Instructions | Cons
  tl.revLocation  = @lhs.revLocation
  hd.revLocation  = @tl.revLocation
  lhs.revLocation = @hd.revLocation

SEM BodyInfo | Info
  instructions.location < instructions.revLocation

-- Branch targets
SEM Instruction
  | LookupSwitch
      loc.relative = fromS24 @defaultOffset
      loc.target = @lhs.location + @loc.relative
  | IfEq IfFalse IfGe IfGt IfLe IfLt IfNGe IfNGt IfNLe IfNLt IfNe IfStrictEq IfStrictNe IfTrue Jump
      loc.relative = fromS24 @offset
      loc.target = @lhs.revLocation + @loc.relative

SEM CaseOffsets | Cons
  loc.relative = fromS24 @hd
  loc.target = @lhs.location + @loc.relative