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-----------------------------------------------------------------------------
--
-- Cmm utilities.
--
-- (c) The University of Glasgow 2004
--
-----------------------------------------------------------------------------
module CmmUtils(
CmmStmts, noStmts, oneStmt, mkStmts, plusStmts, stmtList,
isNopStmt,
isTrivialCmmExpr, hasNoGlobalRegs,
cmmRegOff, cmmLabelOff, cmmOffset, cmmOffsetLit, cmmIndex,
cmmOffsetExpr, cmmIndexExpr, cmmLoadIndex,
mkIntCLit, zeroCLit,
mkLblExpr,
) where
#include "HsVersions.h"
import CLabel ( CLabel )
import Cmm
import MachOp
import OrdList
import Outputable
---------------------------------------------------
--
-- CmmStmts
--
---------------------------------------------------
type CmmStmts = OrdList CmmStmt
noStmts :: CmmStmts
noStmts = nilOL
oneStmt :: CmmStmt -> CmmStmts
oneStmt = unitOL
mkStmts :: [CmmStmt] -> CmmStmts
mkStmts = toOL
plusStmts :: CmmStmts -> CmmStmts -> CmmStmts
plusStmts = appOL
stmtList :: CmmStmts -> [CmmStmt]
stmtList = fromOL
---------------------------------------------------
--
-- CmmStmt
--
---------------------------------------------------
isNopStmt :: CmmStmt -> Bool
-- If isNopStmt returns True, the stmt is definitely a no-op;
-- but it might be a no-op even if isNopStmt returns False
isNopStmt CmmNop = True
isNopStmt (CmmAssign r e) = cheapEqReg r e
isNopStmt (CmmStore e1 (CmmLoad e2 _)) = cheapEqExpr e1 e2
isNopStmt s = False
cheapEqExpr :: CmmExpr -> CmmExpr -> Bool
cheapEqExpr (CmmReg r) e = cheapEqReg r e
cheapEqExpr (CmmRegOff r 0) e = cheapEqReg r e
cheapEqExpr (CmmRegOff r n) (CmmRegOff r' n') = r==r' && n==n'
cheapEqExpr e1 e2 = False
cheapEqReg :: CmmReg -> CmmExpr -> Bool
cheapEqReg r (CmmReg r') = r==r'
cheapEqReg r (CmmRegOff r' 0) = r==r'
cheapEqReg r e = False
---------------------------------------------------
--
-- CmmExpr
--
---------------------------------------------------
isTrivialCmmExpr :: CmmExpr -> Bool
isTrivialCmmExpr (CmmLoad _ _) = False
isTrivialCmmExpr (CmmMachOp _ _) = False
isTrivialCmmExpr (CmmLit _) = True
isTrivialCmmExpr (CmmReg _) = True
isTrivialCmmExpr (CmmRegOff _ _) = True
hasNoGlobalRegs :: CmmExpr -> Bool
hasNoGlobalRegs (CmmLoad e _) = hasNoGlobalRegs e
hasNoGlobalRegs (CmmMachOp _ es) = all hasNoGlobalRegs es
hasNoGlobalRegs (CmmLit _) = True
hasNoGlobalRegs (CmmReg (CmmLocal _)) = True
hasNoGlobalRegs (CmmRegOff (CmmLocal _) _) = True
hasNoGlobalRegs _ = False
---------------------------------------------------
--
-- Expr Construction helpers
--
---------------------------------------------------
cmmOffsetExpr :: CmmExpr -> CmmExpr -> CmmExpr
-- assumes base and offset have the same MachRep
cmmOffsetExpr e (CmmLit (CmmInt n _)) = cmmOffset e (fromInteger n)
cmmOffsetExpr e byte_off = CmmMachOp (MO_Add (cmmExprRep e)) [e, byte_off]
-- NB. Do *not* inspect the value of the offset in these smart constructors!!!
--
-- because the offset is sometimes involved in a loop in the code generator
-- (we don't know the real Hp offset until we've generated code for the entire
-- basic block, for example). So we cannot eliminate zero offsets at this
-- stage; they're eliminated later instead (either during printing or
-- a later optimisation step on Cmm).
--
cmmOffset :: CmmExpr -> Int -> CmmExpr
cmmOffset (CmmReg reg) byte_off = cmmRegOff reg byte_off
cmmOffset (CmmRegOff reg m) byte_off = cmmRegOff reg (m+byte_off)
cmmOffset (CmmLit lit) byte_off = CmmLit (cmmOffsetLit lit byte_off)
cmmOffset (CmmMachOp (MO_Add rep) [expr, CmmLit (CmmInt byte_off1 _rep)]) byte_off2
= CmmMachOp (MO_Add rep)
[expr, CmmLit (CmmInt (byte_off1 + toInteger byte_off2) rep)]
cmmOffset expr byte_off
= CmmMachOp (MO_Add rep) [expr, CmmLit (CmmInt (toInteger byte_off) rep)]
where
rep = cmmExprRep expr
-- Smart constructor for CmmRegOff. Same caveats as cmmOffset above.
cmmRegOff :: CmmReg -> Int -> CmmExpr
cmmRegOff reg byte_off = CmmRegOff reg byte_off
cmmOffsetLit :: CmmLit -> Int -> CmmLit
cmmOffsetLit (CmmLabel l) byte_off = cmmLabelOff l byte_off
cmmOffsetLit (CmmLabelOff l m) byte_off = cmmLabelOff l (m+byte_off)
cmmOffsetLit (CmmInt m rep) byte_off = CmmInt (m + fromIntegral byte_off) rep
cmmOffsetLit other byte_off = pprPanic "cmmOffsetLit" (ppr byte_off)
cmmLabelOff :: CLabel -> Int -> CmmLit
-- Smart constructor for CmmLabelOff
cmmLabelOff lbl 0 = CmmLabel lbl
cmmLabelOff lbl byte_off = CmmLabelOff lbl byte_off
-- | Useful for creating an index into an array, with a staticaly known offset.
cmmIndex :: MachRep -> CmmExpr -> Int -> CmmExpr
cmmIndex rep base idx = cmmOffset base (idx * machRepByteWidth rep)
-- | Useful for creating an index into an array, with an unknown offset.
cmmIndexExpr :: MachRep -> CmmExpr -> CmmExpr -> CmmExpr
cmmIndexExpr rep base (CmmLit (CmmInt n _)) = cmmIndex rep base (fromInteger n)
cmmIndexExpr rep base idx =
cmmOffsetExpr base byte_off
where
idx_rep = cmmExprRep idx
byte_off = CmmMachOp (MO_Shl idx_rep) [
idx, CmmLit (mkIntCLit (machRepLogWidth rep))]
cmmLoadIndex :: MachRep -> CmmExpr -> Int -> CmmExpr
cmmLoadIndex rep expr ix = CmmLoad (cmmIndex rep expr ix) rep
---------------------------------------------------
--
-- Literal construction functions
--
---------------------------------------------------
mkIntCLit :: Int -> CmmLit
mkIntCLit i = CmmInt (toInteger i) wordRep
zeroCLit :: CmmLit
zeroCLit = CmmInt 0 wordRep
mkLblExpr :: CLabel -> CmmExpr
mkLblExpr lbl = CmmLit (CmmLabel lbl)
|
