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|
module GHC.CmmToAsm.Instr
( Instruction(..)
, RegUsage(..)
, noUsage
)
where
import GHC.Prelude
import GHC.Platform
import GHC.Platform.Reg
import GHC.Utils.Outputable (SDoc)
import GHC.Cmm.BlockId
import GHC.CmmToAsm.Config
-- | Holds a list of source and destination registers used by a
-- particular instruction.
--
-- Machine registers that are pre-allocated to stgRegs are filtered
-- out, because they are uninteresting from a register allocation
-- standpoint. (We wouldn't want them to end up on the free list!)
--
-- As far as we are concerned, the fixed registers simply don't exist
-- (for allocation purposes, anyway).
--
data RegUsage
= RU {
reads :: [Reg],
writes :: [Reg]
}
deriving Show
-- | No regs read or written to.
noUsage :: RegUsage
noUsage = RU [] []
-- | Common things that we can do with instructions, on all architectures.
-- These are used by the shared parts of the native code generator,
-- specifically the register allocators.
--
class Instruction instr where
-- | Get the registers that are being used by this instruction.
-- regUsage doesn't need to do any trickery for jumps and such.
-- Just state precisely the regs read and written by that insn.
-- The consequences of control flow transfers, as far as register
-- allocation goes, are taken care of by the register allocator.
--
regUsageOfInstr
:: Platform
-> instr
-> RegUsage
-- | Apply a given mapping to all the register references in this
-- instruction.
patchRegsOfInstr
:: instr
-> (Reg -> Reg)
-> instr
-- | Checks whether this instruction is a jump/branch instruction.
-- One that can change the flow of control in a way that the
-- register allocator needs to worry about.
isJumpishInstr
:: instr -> Bool
-- | Give the possible destinations of this jump instruction.
-- Must be defined for all jumpish instructions.
jumpDestsOfInstr
:: instr -> [BlockId]
-- | Change the destination of this jump instruction.
-- Used in the linear allocator when adding fixup blocks for join
-- points.
patchJumpInstr
:: instr
-> (BlockId -> BlockId)
-> instr
-- | An instruction to spill a register into a spill slot.
mkSpillInstr
:: NCGConfig
-> Reg -- ^ the reg to spill
-> Int -- ^ the current stack delta
-> Int -- ^ spill slot to use
-> [instr] -- ^ instructions
-- | An instruction to reload a register from a spill slot.
mkLoadInstr
:: NCGConfig
-> Reg -- ^ the reg to reload.
-> Int -- ^ the current stack delta
-> Int -- ^ the spill slot to use
-> [instr] -- ^ instructions
-- | See if this instruction is telling us the current C stack delta
takeDeltaInstr
:: instr
-> Maybe Int
-- | Check whether this instruction is some meta thing inserted into
-- the instruction stream for other purposes.
--
-- Not something that has to be treated as a real machine instruction
-- and have its registers allocated.
--
-- eg, comments, delta, ldata, etc.
isMetaInstr
:: instr
-> Bool
-- | Copy the value in a register to another one.
-- Must work for all register classes.
mkRegRegMoveInstr
:: Platform
-> Reg -- ^ source register
-> Reg -- ^ destination register
-> instr
-- | Take the source and destination from this reg -> reg move instruction
-- or Nothing if it's not one
takeRegRegMoveInstr
:: instr
-> Maybe (Reg, Reg)
-- | Make an unconditional jump instruction.
-- For architectures with branch delay slots, its ok to put
-- a NOP after the jump. Don't fill the delay slot with an
-- instruction that references regs or you'll confuse the
-- linear allocator.
mkJumpInstr
:: BlockId
-> [instr]
-- Subtract an amount from the C stack pointer
mkStackAllocInstr
:: Platform
-> Int
-> [instr]
-- Add an amount to the C stack pointer
mkStackDeallocInstr
:: Platform
-> Int
-> [instr]
-- | Pretty-print an instruction
pprInstr :: Platform -> instr -> SDoc
-- Create a comment instruction
mkComment :: SDoc -> [instr]
|
