-- Instruction transformation that turns the jump target of an instruction
-- from a relative location to an absolute location

MODULE {BranchRelToAbs} {branchRelToAbs} {}

INCLUDE "ByteCodeAst.ag"

imports
{
import ByteCode
import Data.Word
import Data.ByteString.Lazy(ByteString)
import InstrSize
}

WRAPPER LabInstruction

{
branchRelToAbs ::  LabInstruction -> LabInstruction
branchRelToAbs m = out where
  inh = Inh_LabInstruction {}
  sem = sem_LabInstruction m
  syn = wrap_LabInstruction sem inh
  out = output_Syn_LabInstruction syn
}


ATTR LabInstruction Instruction CaseOffsets DebugType VirtKind [ | | output : SELF ]
SEM Instruction
  | LookupSwitch
      loc.relative = fromSigned @defaultOffset
      loc.target   = max (@lhs.label + @loc.relative) 0
      loc.abs      = fromIntegral @loc.target
  | IfEq IfFalse IfGe IfGt IfLe IfLt IfNGe IfNGt IfNLe IfNLt IfNe IfStrictEq IfStrictNe IfTrue Jump
      loc.relative = fromSigned @offset
      loc.target   = max (@lhs.label + branchInstrSize + @loc.relative) 0
      loc.abs      = fromIntegral @loc.target

SEM CaseOffsets | Cons
  loc.relative = fromSigned @hd
  loc.target   = max (@lhs.label + @loc.relative) 0
  loc.abs      = fromIntegral @loc.target

SEM Instruction
  | LookupSwitch    lhs.output = Instruction_LookupSwitch (fromIntegral @loc.target) @caseOffsets.output
  | IfEq            lhs.output = Instruction_IfEq @loc.abs
  | IfFalse         lhs.output = Instruction_IfFalse @loc.abs
  | IfGe            lhs.output = Instruction_IfGe @loc.abs
  | IfGt            lhs.output = Instruction_IfGt @loc.abs
  | IfLe            lhs.output = Instruction_IfLe @loc.abs
  | IfLt            lhs.output = Instruction_IfLt @loc.abs
  | IfNGe           lhs.output = Instruction_IfNGe @loc.abs
  | IfNGt           lhs.output = Instruction_IfNGt @loc.abs
  | IfNLe           lhs.output = Instruction_IfNLe @loc.abs
  | IfNLt           lhs.output = Instruction_IfNLt @loc.abs
  | IfNe            lhs.output = Instruction_IfNe @loc.abs
  | IfStrictEq      lhs.output = Instruction_IfStrictEq @loc.abs
  | IfStrictNe      lhs.output = Instruction_IfStrictNe @loc.abs
  | IfTrue          lhs.output = Instruction_IfTrue @loc.abs
  | Jump            lhs.output = Instruction_Jump @loc.abs

SEM CaseOffsets | Cons  lhs.output = @loc.abs : @tl.output


ATTR Instruction CaseOffsets [ label : Int | | ]
SEM LabInstruction | Instr  instruction.label = @label