import Unique ( mkPseudoUnique3 )
import FastString ( FastString(..) )
import PprType ( pprType )
-import ByteCodeInstr ( BCInstr(..), ProtoBCO(..), nameOfProtoBCO )
+import ByteCodeInstr ( BCInstr(..), ProtoBCO(..), nameOfProtoBCO, bciStackUse )
import ByteCodeItbls ( ItblEnv, mkITbls )
import ByteCodeLink ( UnlinkedBCO, UnlinkedBCOExpr, assembleBCO,
- ClosureEnv, HValue, linkSomeBCOs, filterNameMap )
+ ClosureEnv, HValue, linkSomeBCOs, filterNameMap,
+ iNTERP_STACK_CHECK_THRESH )
import List ( intersperse, sortBy )
import Foreign ( Ptr(..), mallocBytes )
-- Create a BCO and do a spot of peephole optimisation on the insns
-- at the same time.
mkProtoBCO nm instrs_ordlist origin
- = ProtoBCO nm (peep (fromOL instrs_ordlist)) origin
+ = ProtoBCO nm maybe_with_stack_check origin
where
+ -- Overestimate the stack usage (in words) of this BCO,
+ -- and if >= iNTERP_STACK_CHECK_THRESH, add an explicit
+ -- stack check. (The interpreter always does a stack check
+ -- for iNTERP_STACK_CHECK_THRESH words at the start of each
+ -- BCO anyway, so we only need to add an explicit on in the
+ -- (hopefully rare) cases when the (overestimated) stack use
+ -- exceeds iNTERP_STACK_CHECK_THRESH.
+ maybe_with_stack_check
+ | stack_overest >= 65535
+ = pprPanic "mkProtoBCO: stack use won't fit in 16 bits"
+ (int stack_overest)
+ | stack_overest >= iNTERP_STACK_CHECK_THRESH
+ = (STKCHECK stack_overest) : peep_d
+ | otherwise
+ = peep_d -- the supposedly common case
+
+ stack_overest = sum (map bciStackUse peep_d)
+ + 10 {- just to be really really sure -}
+
+
+ -- Merge local pushes
+ peep_d = peep (fromOL instrs_ordlist)
+
peep (PUSH_L off1 : PUSH_L off2 : PUSH_L off3 : rest)
= PUSH_LLL off1 (off2-1) (off3-2) : peep rest
peep (PUSH_L off1 : PUSH_L off2 : rest)
\section[ByteCodeInstrs]{Bytecode instruction definitions}
\begin{code}
-module ByteCodeInstr ( BCInstr(..), ProtoBCO(..), nameOfProtoBCO ) where
+module ByteCodeInstr ( BCInstr(..), ProtoBCO(..),
+ nameOfProtoBCO, bciStackUse ) where
#include "HsVersions.h"
data BCInstr
-- Messing with the stack
= ARGCHECK Int
+ | STKCHECK Int
-- Push locals (existing bits of the stack)
| PUSH_L Int{-offset-}
| PUSH_LL Int Int{-2 offsets-}
-- and return as per that.
+instance Outputable a => Outputable (ProtoBCO a) where
+ ppr (ProtoBCO name instrs origin)
+ = (text "ProtoBCO" <+> ppr name <> colon)
+ $$ nest 6 (vcat (map ppr instrs))
+ $$ case origin of
+ Left alts -> vcat (map (pprCoreAlt.deAnnAlt) alts)
+ Right rhs -> pprCoreExpr (deAnnotate rhs)
+
instance Outputable BCInstr where
+ ppr (STKCHECK n) = text "STKCHECK" <+> int n
ppr (ARGCHECK n) = text "ARGCHECK" <+> int n
ppr (PUSH_L offset) = text "PUSH_L " <+> int offset
ppr (PUSH_LL o1 o2) = text "PUSH_LL " <+> int o1 <+> int o2
ppr ENTER = text "ENTER"
ppr (RETURN pk) = text "RETURN " <+> ppr pk
-instance Outputable a => Outputable (ProtoBCO a) where
- ppr (ProtoBCO name instrs origin)
- = (text "ProtoBCO" <+> ppr name <> colon)
- $$ nest 6 (vcat (map ppr instrs))
- $$ case origin of
- Left alts -> vcat (map (pprCoreAlt.deAnnAlt) alts)
- Right rhs -> pprCoreExpr (deAnnotate rhs)
+
+-- The stack use, in words, of each bytecode insn. These _must_ be
+-- correct, or overestimates of reality, to be safe.
+bciStackUse :: BCInstr -> Int
+bciStackUse (STKCHECK n) = 0
+bciStackUse (ARGCHECK n) = 0
+bciStackUse (PUSH_L offset) = 1
+bciStackUse (PUSH_LL o1 o2) = 2
+bciStackUse (PUSH_LLL o1 o2 o3) = 3
+bciStackUse (PUSH_G globalish) = 1
+bciStackUse (PUSH_AS nm pk) = 2
+bciStackUse (PUSH_UBX lit nw) = nw
+bciStackUse (PUSH_TAG n) = 1
+bciStackUse (ALLOC sz) = 1
+bciStackUse (UNPACK sz) = sz
+bciStackUse (UPK_TAG n m k) = n + 1{-tag-}
+bciStackUse (LABEL lab) = 0
+bciStackUse (TESTLT_I i lab) = 0
+bciStackUse (TESTEQ_I i lab) = 0
+bciStackUse (TESTLT_F f lab) = 0
+bciStackUse (TESTEQ_F f lab) = 0
+bciStackUse (TESTLT_D d lab) = 0
+bciStackUse (TESTEQ_D d lab) = 0
+bciStackUse (TESTLT_P i lab) = 0
+bciStackUse (TESTEQ_P i lab) = 0
+bciStackUse CASEFAIL = 0
+bciStackUse ENTER = 0
+bciStackUse (RETURN pk) = 0
+
+-- These insns actually reduce stack use, but we need the high-tide level,
+-- so can't use this info. Not that it matters much.
+bciStackUse (SLIDE n d) = 0
+bciStackUse (MKAP offset sz) = 0
+bciStackUse (PACK dcon sz) = 1 -- worst case is PACK 0 words
+
\end{code}
\begin{code}
module ByteCodeLink ( UnlinkedBCO, UnlinkedBCOExpr, assembleBCO,
- ClosureEnv, HValue, linkSomeBCOs, filterNameMap
+ ClosureEnv, HValue, linkSomeBCOs, filterNameMap,
+ iNTERP_STACK_CHECK_THRESH
) where
#include "HsVersions.h"
doInstr st i
= case i of
ARGCHECK n -> instr2 st i_ARGCHECK n
+ STKCHECK n -> instr2 st i_STKCHECK n
PUSH_L o1 -> instr2 st i_PUSH_L o1
PUSH_LL o1 o2 -> instr3 st i_PUSH_LL o1 o2
PUSH_LLL o1 o2 o3 -> instr4 st i_PUSH_LLL o1 o2 o3
instrSize16s :: BCInstr -> Int
instrSize16s instr
= case instr of
+ STKCHECK _ -> 2
ARGCHECK _ -> 2
PUSH_L _ -> 2
PUSH_LL _ _ -> 3
i_CASEFAIL = (bci_CASEFAIL :: Int)
i_ENTER = (bci_ENTER :: Int)
i_RETURN = (bci_RETURN :: Int)
+i_STKCHECK = (bci_STKCHECK :: Int)
+
+iNTERP_STACK_CHECK_THRESH = (INTERP_STACK_CHECK_THRESH :: Int)
\end{code}