%
% (c) The AQUA Project, Glasgow University, 1993-1998
%

\begin{code}
module StixMacro ( macroCode, checkCode ) where

#include "HsVersions.h"
#include "nativeGen/NCG.h"

import {-# SOURCE #-} StixPrim ( amodeToStix )

import MachRegs
import AbsCSyn		( CStmtMacro(..), CAddrMode, tagreg, CCheckMacro(..) )
import Constants	( uF_RET, uF_UPDATEE, uF_SIZE )
import ForeignCall	( CCallConv(..) )
import MachOp		( MachOp(..) )
import PrimRep		( PrimRep(..) )
import Stix
import Panic		( panic )
import UniqSupply	( returnUs, thenUs, UniqSM )
import CLabel		( mkBlackHoleInfoTableLabel, mkIndStaticInfoLabel,
			  mkIndInfoLabel, mkUpdInfoLabel, mkRtsGCEntryLabel )
\end{code}

The @ARGS_CHK_A{_LOAD_NODE}@ macros check for sufficient arguments on
the A stack, and perform a tail call to @UpdatePAP@ if the arguments are
not there.  The @_LOAD_NODE@ version also loads R1 with an appropriate
closure address.

\begin{code}
macroCode
    :: CStmtMacro   	    -- statement macro
    -> [CAddrMode]  	    -- args
    -> UniqSM StixStmtList
\end{code}

-----------------------------------------------------------------------------
Updating a CAF

@UPD_CAF@ involves changing the info pointer of the closure, and
adding an indirection.

\begin{code}
macroCode UPD_CAF args
  = let
	[cafptr,bhptr] = map amodeToStix args
	new_caf = StVoidable (StCall (Left FSLIT("newCAF")) CCallConv VoidRep [cafptr])
	a1 = StAssignMem PtrRep (StIndex PtrRep cafptr fixedHS) bhptr
	a2 = StAssignMem PtrRep cafptr ind_static_info
    in
    returnUs (\xs -> new_caf : a1 : a2 : xs)
\end{code}

-----------------------------------------------------------------------------
Blackholing

We do lazy blackholing: no need to overwrite thunks with blackholes
the minute they're entered, as long as we do it before a context
switch or garbage collection, that's ok.

Don't blackhole single entry closures, for the following reasons:
	
	- if the compiler has decided that they won't be entered again,
	  that probably means that nothing has a pointer to it
	  (not necessarily true, but...)

	- no need to blackhole for concurrency reasons, because nothing
	  can block on the result of this computation.

\begin{code}
macroCode UPD_BH_UPDATABLE args = returnUs id

macroCode UPD_BH_SINGLE_ENTRY args = returnUs id
{-
  = let
    	update = StAssign PtrRep (StInd PtrRep (amodeToStix arg)) bh_info
    in
    returnUs (\xs -> update : xs)
-}
\end{code}

-----------------------------------------------------------------------------
Update frames

Push an update frame on the stack.

\begin{code}
macroCode PUSH_UPD_FRAME args
  = let
	[bhptr, _{-0-}] = map amodeToStix args
    	frame n = StIndex PtrRep (StReg stgSp) (StInt (toInteger (n-uF_SIZE)))

        -- HWL: these values are *wrong* in a GranSim setup; ToDo: fix
	a1 = StAssignMem PtrRep (frame uF_RET)     upd_frame_info
	a4 = StAssignMem PtrRep (frame uF_UPDATEE) bhptr
    in
    returnUs (\xs -> a1 : a4 : xs)
\end{code}

-----------------------------------------------------------------------------
Setting the tag register

This one only applies if we have a machine register devoted to TagReg.

\begin{code}
macroCode SET_TAG [tag]
  = case get_MagicId_reg_or_addr tagreg of
       Right baseRegAddr 
          -> returnUs id
       Left  realreg 
          -> let a1 = StAssignReg IntRep (StixMagicId tagreg) (amodeToStix tag)
             in returnUs ( \xs -> a1 : xs )
\end{code}

-----------------------------------------------------------------------------

\begin{code}
macroCode REGISTER_IMPORT [arg]
   = returnUs (
	\xs -> StAssignMem WordRep (StReg stgSp) (amodeToStix arg)
	     : StAssignReg PtrRep  stgSp (StMachOp MO_Nat_Add [StReg stgSp, StInt 4])
	     : xs
     )

macroCode REGISTER_FOREIGN_EXPORT [arg]
   = returnUs (
	\xs -> StVoidable (
                  StCall (Left FSLIT("getStablePtr")) CCallConv VoidRep 
                         [amodeToStix arg]
               )
	     : xs
     )

macroCode other args
   = panic "StixMacro.macroCode"
\end{code}

Do the business for a @HEAP_CHK@, having converted the args to Trees
of StixOp.

-----------------------------------------------------------------------------
Let's make sure that these CAFs are lifted out, shall we?

\begin{code}
-- Some common labels

bh_info, ind_static_info, ind_info :: StixExpr

bh_info   	= StCLbl mkBlackHoleInfoTableLabel
ind_static_info	= StCLbl mkIndStaticInfoLabel
ind_info  	= StCLbl mkIndInfoLabel
upd_frame_info	= StCLbl mkUpdInfoLabel

-- Some common call trees
\end{code}

-----------------------------------------------------------------------------
Heap/Stack checks

\begin{code}
checkCode :: CCheckMacro -> [CAddrMode] -> StixStmtList -> UniqSM StixStmtList
checkCode macro args assts
  = getUniqLabelNCG		`thenUs` \ ulbl_fail ->
    getUniqLabelNCG		`thenUs` \ ulbl_pass ->

    let args_stix        = map amodeToStix args
	newHp wds        = StIndex PtrRep (StReg stgHp) wds
	assign_hp wds    = StAssignReg PtrRep stgHp (newHp wds)
	hp_alloc wds     = StAssignReg IntRep stgHpAlloc wds
	test_hp          = StMachOp MO_NatU_Le [StReg stgHp, StReg stgHpLim]
	cjmp_hp          = StCondJump ulbl_pass test_hp
	newSp wds        = StIndex PtrRep (StReg stgSp) (StMachOp MO_NatS_Neg [wds])
	test_sp_pass wds = StMachOp MO_NatU_Ge [newSp wds, StReg stgSpLim]
	test_sp_fail wds = StMachOp MO_NatU_Lt [newSp wds, StReg stgSpLim]
	cjmp_sp_pass wds = StCondJump ulbl_pass (test_sp_pass wds)
	cjmp_sp_fail wds = StCondJump ulbl_fail (test_sp_fail wds)
	assign_ret r ret = mkStAssign CodePtrRep r ret

	fail = StLabel ulbl_fail
	join = StLabel ulbl_pass

        -- see includes/StgMacros.h for explaination of these magic consts
        aLL_NON_PTRS = 0xff

        assign_liveness ptr_regs 
           = StAssignReg WordRep stgR9
                         (StMachOp MO_Nat_Xor [StInt aLL_NON_PTRS, ptr_regs])
        assign_reentry reentry 
           = StAssignReg WordRep stgR10 reentry
    in	

    returnUs (
    case macro of
	HP_CHK_NP      -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_enter : join : xs))

	STK_CHK_NP     -> 
		let [words] = args_stix
		in  (\xs -> cjmp_sp_pass words :
			    assts (gc_enter : join : xs))

	HP_STK_CHK_NP  -> 
		let [sp_words,hp_words] = args_stix
		in  (\xs -> cjmp_sp_fail sp_words : 
			    assign_hp hp_words : cjmp_hp :
			    fail :
			    assts (hp_alloc hp_words : gc_enter
				   : join : xs))

	HP_CHK_FUN       -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp :
			    assts (hp_alloc words : gc_fun : join : xs))

	STK_CHK_FUN       -> 
		let [words] = args_stix
		in  (\xs -> cjmp_sp_pass words :
			    assts (gc_fun : join : xs))

	HP_STK_CHK_FUN    -> 
		let [sp_words,hp_words] = args_stix
		in  (\xs -> cjmp_sp_fail sp_words :
			    assign_hp hp_words : cjmp_hp :
			    fail :
			    assts (hp_alloc hp_words
				  : gc_fun : join : xs))

	HP_CHK_NOREGS  -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_noregs : join : xs))

	HP_CHK_UNPT_R1 -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_unpt_r1 : join : xs))

	HP_CHK_UNBX_R1 -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_unbx_r1 : join : xs))

	HP_CHK_F1      -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_f1 : join : xs))

	HP_CHK_D1      -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_d1 : join : xs))

	HP_CHK_L1      -> 
		let [words] = args_stix
		in  (\xs -> assign_hp words : cjmp_hp : 
			    assts (hp_alloc words : gc_l1 : join : xs))

	HP_CHK_UNBX_TUPLE  -> 
                let [words,liveness] = args_stix
                in (\xs -> assign_hp words : cjmp_hp :
                           assts (hp_alloc words : assign_liveness liveness :
                                  gc_ut : join : xs))
    )

-- Various canned heap-check routines

mkStJump_to_GCentry_name :: String -> StixStmt
mkStJump_to_GCentry_name gcname
--   | opt_Static
   = StJump NoDestInfo (StCLbl (mkRtsGCEntryLabel gcname))
--   | otherwise -- it's in a different DLL
--   = StJump (StInd PtrRep (StLitLbl True sdoc))

mkStJump_to_RegTable_offw :: Int -> StixStmt
mkStJump_to_RegTable_offw regtable_offw
--   | opt_Static
   = StJump NoDestInfo (StInd PtrRep (get_Regtable_addr_from_offset regtable_offw))
--   | otherwise
--   do something plausible for cross-DLL jump

gc_enter = mkStJump_to_RegTable_offw OFFSET_stgGCEnter1
gc_fun   = mkStJump_to_RegTable_offw OFFSET_stgGCFun

gc_noregs          = mkStJump_to_GCentry_name "stg_gc_noregs"
gc_unpt_r1         = mkStJump_to_GCentry_name "stg_gc_unpt_r1"
gc_unbx_r1         = mkStJump_to_GCentry_name "stg_gc_unbx_r1"
gc_f1              = mkStJump_to_GCentry_name "stg_gc_f1"
gc_d1              = mkStJump_to_GCentry_name "stg_gc_d1"
gc_l1              = mkStJump_to_GCentry_name "stg_gc_l1"
gc_ut              = mkStJump_to_GCentry_name "stg_gc_ut"
\end{code}