-%
-% (c) The AQUA Project, Glasgow University, 1993-1998
-%
+-- -----------------------------------------------------------------------------
+--
+-- (c) The University of Glasgow 1993-2004
+--
+-- This is the top-level module in the native code generator.
+--
+-- -----------------------------------------------------------------------------
\begin{code}
module AsmCodeGen ( nativeCodeGen ) where
#include "HsVersions.h"
#include "NCG.h"
-import MachMisc
+import MachInstrs
import MachRegs
-import MachCode
+import MachCodeGen
import PprMach
-
-import AbsCStixGen ( genCodeAbstractC )
-import AbsCSyn ( AbstractC, MagicId(..) )
-import AbsCUtils ( mkAbsCStmtList, magicIdPrimRep )
-import AsmRegAlloc ( runRegAllocate )
-import MachOp ( MachOp(..), isCommutableMachOp, isComparisonMachOp )
-import RegAllocInfo ( findReservedRegs )
-import Stix ( StixReg(..), StixStmt(..), StixExpr(..), StixVReg(..),
- pprStixStmts, pprStixStmt,
- stixStmt_CountTempUses, stixStmt_Subst,
- liftStrings,
- initNat,
- mkNatM_State,
- uniqOfNatM_State, deltaOfNatM_State,
- importsOfNatM_State )
-import UniqSupply ( returnUs, thenUs, initUs,
- UniqSM, UniqSupply,
- lazyMapUs )
-import MachMisc ( IF_ARCH_i386(i386_insert_ffrees,) )
-#if darwin_TARGET_OS
-import PprMach ( pprDyldSymbolStub )
-import List ( group, sort )
+import RegisterAlloc
+import RegAllocInfo ( jumpDests )
+import NCGMonad
+import PositionIndependentCode
+
+import Cmm
+import CmmOpt ( cmmMiniInline, cmmMachOpFold )
+import PprCmm ( pprStmt, pprCmms )
+import MachOp
+import CLabel ( CLabel, mkSplitMarkerLabel, mkAsmTempLabel )
+#if powerpc_TARGET_ARCH
+import CLabel ( mkRtsCodeLabel )
#endif
+import UniqFM
+import Unique ( Unique, getUnique )
+import UniqSupply
+import FastTypes
+import List ( groupBy, sortBy )
+import CLabel ( pprCLabel )
+import ErrUtils ( dumpIfSet_dyn )
+import DynFlags ( DynFlags, DynFlag(..), dopt )
+import StaticFlags ( opt_Static, opt_PIC )
+
+import Digraph
import qualified Pretty
import Outputable
import FastString
-- DEBUGGING ONLY
--import OrdList
+#ifdef NCG_DEBUG
import List ( intersperse )
-\end{code}
+#endif
+
+import DATA_INT
+import DATA_WORD
+import DATA_BITS
+import GLAEXTS
-The 96/03 native-code generator has machine-independent and
-machine-dependent modules (those \tr{#include}'ing \tr{NCG.h}).
+{-
+The native-code generator has machine-independent and
+machine-dependent modules.
-This module (@AsmCodeGen@) is the top-level machine-independent
-module. It uses @AbsCStixGen.genCodeAbstractC@ to produce @StixTree@s
-(defined in module @Stix@), using support code from @StixPrim@
-(primitive operations), @StixMacro@ (Abstract C macros), and
-@StixInteger@ (GMP arbitrary-precision operations).
+This module ("AsmCodeGen") is the top-level machine-independent
+module. Before entering machine-dependent land, we do some
+machine-independent optimisations (defined below) on the
+'CmmStmts's.
-Before entering machine-dependent land, we do some machine-independent
-@genericOpt@imisations (defined below) on the @StixTree@s.
+We convert to the machine-specific 'Instr' datatype with
+'cmmCodeGen', assuming an infinite supply of registers. We then use
+a machine-independent register allocator ('regAlloc') to rejoin
+reality. Obviously, 'regAlloc' has machine-specific helper
+functions (see about "RegAllocInfo" below).
-We convert to the machine-specific @Instr@ datatype with
-@stmt2Instrs@, assuming an ``infinite'' supply of registers. We then
-use a machine-independent register allocator (@runRegAllocate@) to
-rejoin reality. Obviously, @runRegAllocate@ has machine-specific
-helper functions (see about @RegAllocInfo@ below).
+Finally, we order the basic blocks of the function so as to minimise
+the number of jumps between blocks, by utilising fallthrough wherever
+possible.
The machine-dependent bits break down as follows:
-\begin{description}
-\item[@MachRegs@:] Everything about the target platform's machine
+
+ * ["MachRegs"] Everything about the target platform's machine
registers (and immediate operands, and addresses, which tend to
intermingle/interact with registers).
-\item[@MachMisc@:] Includes the @Instr@ datatype (possibly should
+ * ["MachInstrs"] Includes the 'Instr' datatype (possibly should
have a module of its own), plus a miscellany of other things
- (e.g., @targetDoubleSize@, @smStablePtrTable@, ...)
+ (e.g., 'targetDoubleSize', 'smStablePtrTable', ...)
-\item[@MachCode@:] @stmt2Instrs@ is where @Stix@ stuff turns into
+ * ["MachCodeGen"] is where 'Cmm' stuff turns into
machine instructions.
-\item[@PprMach@:] @pprInstr@ turns an @Instr@ into text (well, really
- an @Doc@).
+ * ["PprMach"] 'pprInstr' turns an 'Instr' into text (well, really
+ a 'Doc').
-\item[@RegAllocInfo@:] In the register allocator, we manipulate
- @MRegsState@s, which are @BitSet@s, one bit per machine register.
+ * ["RegAllocInfo"] In the register allocator, we manipulate
+ 'MRegsState's, which are 'BitSet's, one bit per machine register.
When we want to say something about a specific machine register
(e.g., ``it gets clobbered by this instruction''), we set/unset
- its bit. Obviously, we do this @BitSet@ thing for efficiency
+ its bit. Obviously, we do this 'BitSet' thing for efficiency
reasons.
- The @RegAllocInfo@ module collects together the machine-specific
+ The 'RegAllocInfo' module collects together the machine-specific
info needed to do register allocation.
-\end{description}
-So, here we go:
-
-\begin{code}
-nativeCodeGen :: AbstractC -> UniqSupply -> (SDoc, Pretty.Doc)
-nativeCodeGen absC us
- = let absCstmts = mkAbsCStmtList absC
- (results, us1) = initUs us (lazyMapUs absCtoNat absCstmts)
- stix_sdocs = [ stix | (stix, insn, imports) <- results ]
- insn_sdocs = [ insn | (stix, insn, imports) <- results ]
- imports = [ imports | (stix, insn, imports) <- results ]
-
- insn_sdoc = my_vcat insn_sdocs IF_OS_darwin(Pretty.$$ dyld_stubs,)
- stix_sdoc = vcat stix_sdocs
-
-#if darwin_TARGET_OS
- -- Generate "symbol stubs" for all external symbols that might
- -- come from a dynamic library.
-
- dyld_stubs = Pretty.vcat $ map pprDyldSymbolStub $
- map head $ group $ sort $ concat imports
+ * ["RegisterAlloc"] The (machine-independent) register allocator.
+-}
+
+-- -----------------------------------------------------------------------------
+-- Top-level of the native codegen
+
+-- NB. We *lazilly* compile each block of code for space reasons.
+
+nativeCodeGen :: DynFlags -> [Cmm] -> UniqSupply -> IO Pretty.Doc
+nativeCodeGen dflags cmms us
+ = let (res, _) = initUs us $
+ cgCmm (concat (map add_split cmms))
+
+ cgCmm :: [CmmTop] -> UniqSM (Cmm, Pretty.Doc, [CLabel])
+ cgCmm tops =
+ lazyMapUs (cmmNativeGen dflags) tops `thenUs` \ results ->
+ case unzip3 results of { (cmms,docs,imps) ->
+ returnUs (Cmm cmms, my_vcat docs, concat imps)
+ }
+ in
+ case res of { (ppr_cmms, insn_sdoc, imports) -> do
+ dumpIfSet_dyn dflags Opt_D_dump_opt_cmm "Optimised Cmm" (pprCmms [ppr_cmms])
+ return (insn_sdoc Pretty.$$ dyld_stubs imports
+#if HAVE_SUBSECTIONS_VIA_SYMBOLS
+ -- On recent versions of Darwin, the linker supports
+ -- dead-stripping of code and data on a per-symbol basis.
+ -- There's a hack to make this work in PprMach.pprNatCmmTop.
+ Pretty.$$ Pretty.text ".subsections_via_symbols"
#endif
+ )
+ }
-# ifdef NCG_DEBUG
- my_trace m x = trace m x
- my_vcat sds = Pretty.vcat (
- intersperse (
- Pretty.char ' '
- Pretty.$$ Pretty.ptext SLIT("# ___ncg_debug_marker")
- Pretty.$$ Pretty.char ' '
- )
- sds
- )
-# else
- my_vcat sds = Pretty.vcat sds
- my_trace m x = x
-# endif
- in
- my_trace "nativeGen: begin"
- (stix_sdoc, insn_sdoc)
-
-
-absCtoNat :: AbstractC -> UniqSM (SDoc, Pretty.Doc, [FastString])
-absCtoNat absC
- = _scc_ "genCodeAbstractC" genCodeAbstractC absC `thenUs` \ stixRaw ->
- _scc_ "genericOpt" genericOpt stixRaw `bind` \ stixOpt ->
- _scc_ "liftStrings" liftStrings stixOpt `thenUs` \ stixLifted ->
- _scc_ "genMachCode" genMachCode stixLifted `thenUs` \ (pre_regalloc, imports) ->
- _scc_ "regAlloc" regAlloc pre_regalloc `bind` \ almost_final ->
- _scc_ "x86fp_kludge" x86fp_kludge almost_final `bind` \ final_mach_code ->
- _scc_ "vcat" Pretty.vcat (map pprInstr final_mach_code) `bind` \ final_sdoc ->
- _scc_ "pprStixTrees" pprStixStmts stixOpt `bind` \ stix_sdoc ->
- returnUs ({-\_ -> Pretty.vcat (map pprInstr almost_final),-}
- stix_sdoc, final_sdoc, imports)
- where
- bind f x = x f
+ where
- x86fp_kludge :: [Instr] -> [Instr]
- x86fp_kludge = IF_ARCH_i386(i386_insert_ffrees,id)
+ add_split (Cmm tops)
+ | dopt Opt_SplitObjs dflags = split_marker : tops
+ | otherwise = tops
- regAlloc :: InstrBlock -> [Instr]
- regAlloc = runRegAllocate allocatableRegs findReservedRegs
-\end{code}
+ split_marker = CmmProc [] mkSplitMarkerLabel [] []
-Top level code generator for a chunk of stix code. For this part of
-the computation, we switch from the UniqSM monad to the NatM monad.
-The latter carries not only a Unique, but also an Int denoting the
-current C stack pointer offset in the generated code; this is needed
-for creating correct spill offsets on architectures which don't offer,
-or for which it would be prohibitively expensive to employ, a frame
-pointer register. Viz, x86.
-
-The offset is measured in bytes, and indicates the difference between
-the current (simulated) C stack-ptr and the value it was at the
-beginning of the block. For stacks which grow down, this value should
-be either zero or negative.
+ -- Generate "symbol stubs" for all external symbols that might
+ -- come from a dynamic library.
+{- dyld_stubs imps = Pretty.vcat $ map pprDyldSymbolStub $
+ map head $ group $ sort imps-}
+
+ -- (Hack) sometimes two Labels pretty-print the same, but have
+ -- different uniques; so we compare their text versions...
+ dyld_stubs imps
+ | needImportedSymbols
+ = Pretty.vcat $
+ (pprGotDeclaration :) $
+ map (pprImportedSymbol . fst . head) $
+ groupBy (\(_,a) (_,b) -> a == b) $
+ sortBy (\(_,a) (_,b) -> compare a b) $
+ map doPpr $
+ imps
+ | otherwise
+ = Pretty.empty
+
+ where doPpr lbl = (lbl, Pretty.render $ pprCLabel lbl astyle)
+ astyle = mkCodeStyle AsmStyle
+
+#ifndef NCG_DEBUG
+ my_vcat sds = Pretty.vcat sds
+#else
+ my_vcat sds = Pretty.vcat (
+ intersperse (
+ Pretty.char ' '
+ Pretty.$$ Pretty.ptext SLIT("# ___ncg_debug_marker")
+ Pretty.$$ Pretty.char ' '
+ )
+ sds
+ )
+#endif
-Switching between the two monads whilst carrying along the same Unique
-supply breaks abstraction. Is that bad?
-\begin{code}
-genMachCode :: [StixStmt] -> UniqSM (InstrBlock, [FastString])
+-- Complete native code generation phase for a single top-level chunk
+-- of Cmm.
+
+cmmNativeGen :: DynFlags -> CmmTop -> UniqSM (CmmTop, Pretty.Doc, [CLabel])
+cmmNativeGen dflags cmm
+ = {-# SCC "fixAssigns" #-}
+ fixAssignsTop cmm `thenUs` \ fixed_cmm ->
+ {-# SCC "genericOpt" #-}
+ cmmToCmm fixed_cmm `bind` \ (cmm, imports) ->
+ (if dopt Opt_D_dump_opt_cmm dflags -- space leak avoidance
+ then cmm
+ else CmmData Text []) `bind` \ ppr_cmm ->
+ {-# SCC "genMachCode" #-}
+ genMachCode cmm `thenUs` \ (pre_regalloc, lastMinuteImports) ->
+ {-# SCC "regAlloc" #-}
+ map regAlloc pre_regalloc `bind` \ with_regs ->
+ {-# SCC "sequenceBlocks" #-}
+ map sequenceTop with_regs `bind` \ sequenced ->
+ {-# SCC "x86fp_kludge" #-}
+ map x86fp_kludge sequenced `bind` \ final_mach_code ->
+ {-# SCC "vcat" #-}
+ Pretty.vcat (map pprNatCmmTop final_mach_code) `bind` \ final_sdoc ->
+
+ returnUs (ppr_cmm, final_sdoc Pretty.$$ Pretty.text "", lastMinuteImports ++ imports)
+ where
+ x86fp_kludge :: NatCmmTop -> NatCmmTop
+ x86fp_kludge top@(CmmData _ _) = top
+#if i386_TARGET_ARCH
+ x86fp_kludge top@(CmmProc info lbl params code) =
+ CmmProc info lbl params (map bb_i386_insert_ffrees code)
+ where
+ bb_i386_insert_ffrees (BasicBlock id instrs) =
+ BasicBlock id (i386_insert_ffrees instrs)
+#else
+ x86fp_kludge top = top
+#endif
-genMachCode stmts initial_us
+-- -----------------------------------------------------------------------------
+-- Sequencing the basic blocks
+
+-- Cmm BasicBlocks are self-contained entities: they always end in a
+-- jump, either non-local or to another basic block in the same proc.
+-- In this phase, we attempt to place the basic blocks in a sequence
+-- such that as many of the local jumps as possible turn into
+-- fallthroughs.
+
+sequenceTop :: NatCmmTop -> NatCmmTop
+sequenceTop top@(CmmData _ _) = top
+sequenceTop (CmmProc info lbl params blocks) =
+ CmmProc info lbl params (sequenceBlocks blocks)
+
+-- The algorithm is very simple (and stupid): we make a graph out of
+-- the blocks where there is an edge from one block to another iff the
+-- first block ends by jumping to the second. Then we topologically
+-- sort this graph. Then traverse the list: for each block, we first
+-- output the block, then if it has an out edge, we move the
+-- destination of the out edge to the front of the list, and continue.
+
+sequenceBlocks :: [NatBasicBlock] -> [NatBasicBlock]
+sequenceBlocks [] = []
+sequenceBlocks (entry:blocks) =
+ seqBlocks (mkNode entry : reverse (flattenSCCs (sccBlocks blocks)))
+ -- the first block is the entry point ==> it must remain at the start.
+
+sccBlocks :: [NatBasicBlock] -> [SCC (NatBasicBlock,Unique,[Unique])]
+sccBlocks blocks = stronglyConnCompR (map mkNode blocks)
+
+getOutEdges :: [Instr] -> [Unique]
+getOutEdges instrs = case jumpDests (last instrs) [] of
+ [one] -> [getUnique one]
+ _many -> []
+ -- we're only interested in the last instruction of
+ -- the block, and only if it has a single destination.
+
+mkNode block@(BasicBlock id instrs) = (block, getUnique id, getOutEdges instrs)
+
+seqBlocks [] = []
+seqBlocks ((block,_,[]) : rest)
+ = block : seqBlocks rest
+seqBlocks ((block@(BasicBlock id instrs),_,[next]) : rest)
+ | can_fallthrough = BasicBlock id (init instrs) : seqBlocks rest'
+ | otherwise = block : seqBlocks rest'
+ where
+ (can_fallthrough, rest') = reorder next [] rest
+ -- TODO: we should do a better job for cycles; try to maximise the
+ -- fallthroughs within a loop.
+seqBlocks _ = panic "AsmCodegen:seqBlocks"
+
+reorder id accum [] = (False, reverse accum)
+reorder id accum (b@(block,id',out) : rest)
+ | id == id' = (True, (block,id,out) : reverse accum ++ rest)
+ | otherwise = reorder id (b:accum) rest
+
+-- -----------------------------------------------------------------------------
+-- Instruction selection
+
+-- Native code instruction selection for a chunk of stix code. For
+-- this part of the computation, we switch from the UniqSM monad to
+-- the NatM monad. The latter carries not only a Unique, but also an
+-- Int denoting the current C stack pointer offset in the generated
+-- code; this is needed for creating correct spill offsets on
+-- architectures which don't offer, or for which it would be
+-- prohibitively expensive to employ, a frame pointer register. Viz,
+-- x86.
+
+-- The offset is measured in bytes, and indicates the difference
+-- between the current (simulated) C stack-ptr and the value it was at
+-- the beginning of the block. For stacks which grow down, this value
+-- should be either zero or negative.
+
+-- Switching between the two monads whilst carrying along the same
+-- Unique supply breaks abstraction. Is that bad?
+
+genMachCode :: CmmTop -> UniqSM ([NatCmmTop], [CLabel])
+
+genMachCode cmm_top initial_us
= let initial_st = mkNatM_State initial_us 0
- (instr_list, final_st) = initNat initial_st (stmtsToInstrs stmts)
- final_us = uniqOfNatM_State final_st
- final_delta = deltaOfNatM_State final_st
- final_imports = importsOfNatM_State final_st
+ (new_tops, final_st) = initNat initial_st (cmmTopCodeGen cmm_top)
+ final_us = natm_us final_st
+ final_delta = natm_delta final_st
+ final_imports = natm_imports final_st
in
if final_delta == 0
- then ((instr_list, final_imports), final_us)
+ then ((new_tops, final_imports), final_us)
else pprPanic "genMachCode: nonzero final delta"
(int final_delta)
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[NCOpt]{The Generic Optimiser}
-%* *
-%************************************************************************
-
-This is called between translating Abstract C to its Tree and actually
-using the Native Code Generator to generate the annotations. It's a
-chance to do some strength reductions.
-
-** Remember these all have to be machine independent ***
-
-Note that constant-folding should have already happened, but we might
-have introduced some new opportunities for constant-folding wrt
-address manipulations.
-
-\begin{code}
-genericOpt :: [StixStmt] -> [StixStmt]
-genericOpt = map stixStmt_ConFold . stixPeep
-
-
-
-stixPeep :: [StixStmt] -> [StixStmt]
-
--- This transformation assumes that the temp assigned to in t1
--- is not assigned to in t2; for otherwise the target of the
--- second assignment would be substituted for, giving nonsense
--- code. As far as I can see, StixTemps are only ever assigned
--- to once. It would be nice to be sure!
-stixPeep ( t1@(StAssignReg pka (StixTemp (StixVReg u pk)) rhs)
- : t2
- : ts )
- | stixStmt_CountTempUses u t2 == 1
- && sum (map (stixStmt_CountTempUses u) ts) == 0
- =
-# ifdef NCG_DEBUG
- trace ("nativeGen: inlining " ++ showSDoc (pprStixExpr rhs))
-# endif
- (stixPeep (stixStmt_Subst u rhs t2 : ts))
-
-stixPeep (t1:t2:ts) = t1 : stixPeep (t2:ts)
-stixPeep [t1] = [t1]
-stixPeep [] = []
-\end{code}
-
-For most nodes, just optimize the children.
-
-\begin{code}
-stixExpr_ConFold :: StixExpr -> StixExpr
-stixStmt_ConFold :: StixStmt -> StixStmt
-
-stixStmt_ConFold stmt
+-- -----------------------------------------------------------------------------
+-- Fixup assignments to global registers so that they assign to
+-- locations within the RegTable, if appropriate.
+
+-- Note that we currently don't fixup reads here: they're done by
+-- the generic optimiser below, to avoid having two separate passes
+-- over the Cmm.
+
+fixAssignsTop :: CmmTop -> UniqSM CmmTop
+fixAssignsTop top@(CmmData _ _) = returnUs top
+fixAssignsTop (CmmProc info lbl params blocks) =
+ mapUs fixAssignsBlock blocks `thenUs` \ blocks' ->
+ returnUs (CmmProc info lbl params blocks')
+
+fixAssignsBlock :: CmmBasicBlock -> UniqSM CmmBasicBlock
+fixAssignsBlock (BasicBlock id stmts) =
+ fixAssigns stmts `thenUs` \ stmts' ->
+ returnUs (BasicBlock id stmts')
+
+fixAssigns :: [CmmStmt] -> UniqSM [CmmStmt]
+fixAssigns stmts =
+ mapUs fixAssign stmts `thenUs` \ stmtss ->
+ returnUs (concat stmtss)
+
+fixAssign :: CmmStmt -> UniqSM [CmmStmt]
+fixAssign (CmmAssign (CmmGlobal BaseReg) src)
+ = panic "cmmStmtConFold: assignment to BaseReg";
+
+fixAssign (CmmAssign (CmmGlobal reg) src)
+ | Left realreg <- reg_or_addr
+ = returnUs [CmmAssign (CmmGlobal reg) src]
+ | Right baseRegAddr <- reg_or_addr
+ = returnUs [CmmStore baseRegAddr src]
+ -- Replace register leaves with appropriate StixTrees for
+ -- the given target. GlobalRegs which map to a reg on this
+ -- arch are left unchanged. Assigning to BaseReg is always
+ -- illegal, so we check for that.
+ where
+ reg_or_addr = get_GlobalReg_reg_or_addr reg
+
+fixAssign (CmmCall target results args vols)
+ = mapAndUnzipUs fixResult results `thenUs` \ (results',stores) ->
+ returnUs (caller_save ++
+ CmmCall target results' args vols :
+ caller_restore ++
+ concat stores)
+ where
+ -- we also save/restore any caller-saves STG registers here
+ (caller_save, caller_restore) = callerSaveVolatileRegs vols
+
+ fixResult g@(CmmGlobal reg,hint) =
+ case get_GlobalReg_reg_or_addr reg of
+ Left realreg -> returnUs (g, [])
+ Right baseRegAddr ->
+ getUniqueUs `thenUs` \ uq ->
+ let local = CmmLocal (LocalReg uq (globalRegRep reg)) in
+ returnUs ((local,hint),
+ [CmmStore baseRegAddr (CmmReg local)])
+ fixResult other =
+ returnUs (other,[])
+
+fixAssign other_stmt = returnUs [other_stmt]
+
+-- -----------------------------------------------------------------------------
+-- Generic Cmm optimiser
+
+{-
+Here we do:
+
+ (a) Constant folding
+ (b) Simple inlining: a temporary which is assigned to and then
+ used, once, can be shorted.
+ (c) Replacement of references to GlobalRegs which do not have
+ machine registers by the appropriate memory load (eg.
+ Hp ==> *(BaseReg + 34) ).
+ (d) Position independent code and dynamic linking
+ (i) introduce the appropriate indirections
+ and position independent refs
+ (ii) compile a list of imported symbols
+
+Ideas for other things we could do (ToDo):
+
+ - shortcut jumps-to-jumps
+ - eliminate dead code blocks
+ - simple CSE: if an expr is assigned to a temp, then replace later occs of
+ that expr with the temp, until the expr is no longer valid (can push through
+ temp assignments, and certain assigns to mem...)
+-}
+
+cmmToCmm :: CmmTop -> (CmmTop, [CLabel])
+cmmToCmm top@(CmmData _ _) = (top, [])
+cmmToCmm (CmmProc info lbl params blocks) = runCmmOpt $ do
+ blocks' <- mapM cmmBlockConFold (cmmMiniInline blocks)
+ return $ CmmProc info lbl params blocks'
+
+newtype CmmOptM a = CmmOptM ([CLabel] -> (# a, [CLabel] #))
+
+instance Monad CmmOptM where
+ return x = CmmOptM $ \imports -> (# x,imports #)
+ (CmmOptM f) >>= g =
+ CmmOptM $ \imports ->
+ case f imports of
+ (# x, imports' #) ->
+ case g x of
+ CmmOptM g' -> g' imports'
+
+addImportCmmOpt :: CLabel -> CmmOptM ()
+addImportCmmOpt lbl = CmmOptM $ \imports -> (# (), lbl:imports #)
+
+runCmmOpt :: CmmOptM a -> (a, [CLabel])
+runCmmOpt (CmmOptM f) = case f [] of
+ (# result, imports #) -> (result, imports)
+
+cmmBlockConFold :: CmmBasicBlock -> CmmOptM CmmBasicBlock
+cmmBlockConFold (BasicBlock id stmts) = do
+ stmts' <- mapM cmmStmtConFold stmts
+ return $ BasicBlock id stmts'
+
+cmmStmtConFold stmt
= case stmt of
- StAssignReg pk reg@(StixTemp _) src
- -> StAssignReg pk reg (stixExpr_ConFold src)
- StAssignReg pk reg@(StixMagicId mid) src
- -- Replace register leaves with appropriate StixTrees for
- -- the given target. MagicIds which map to a reg on this arch are left unchanged.
- -- Assigning to BaseReg is always illegal, so we check for that.
- -> case mid of {
- BaseReg -> panic "stixStmt_ConFold: assignment to BaseReg";
- other ->
- case get_MagicId_reg_or_addr mid of
- Left realreg
- -> StAssignReg pk reg (stixExpr_ConFold src)
- Right baseRegAddr
- -> stixStmt_ConFold (StAssignMem pk baseRegAddr src)
- }
- StAssignMem pk addr src
- -> StAssignMem pk (stixExpr_ConFold addr) (stixExpr_ConFold src)
- StVoidable expr
- -> StVoidable (stixExpr_ConFold expr)
- StJump dsts addr
- -> StJump dsts (stixExpr_ConFold addr)
- StCondJump addr test
- -> let test_opt = stixExpr_ConFold test
- in
- if manifestlyZero test_opt
- then StComment (mkFastString ("deleted: " ++ showSDoc (pprStixStmt stmt)))
- else StCondJump addr (stixExpr_ConFold test)
- StData pk datas
- -> StData pk (map stixExpr_ConFold datas)
+ CmmAssign reg src
+ -> do src' <- cmmExprConFold False src
+ return $ case src' of
+ CmmReg reg' | reg == reg' -> CmmNop
+ new_src -> CmmAssign reg new_src
+
+ CmmStore addr src
+ -> do addr' <- cmmExprConFold False addr
+ src' <- cmmExprConFold False src
+ return $ CmmStore addr' src'
+
+ CmmJump addr regs
+ -> do addr' <- cmmExprConFold True addr
+ return $ CmmJump addr' regs
+
+ CmmCall target regs args vols
+ -> do target' <- case target of
+ CmmForeignCall e conv -> do
+ e' <- cmmExprConFold True e
+ return $ CmmForeignCall e' conv
+ other -> return other
+ args' <- mapM (\(arg, hint) -> do
+ arg' <- cmmExprConFold False arg
+ return (arg', hint)) args
+ return $ CmmCall target' regs args' vols
+
+ CmmCondBranch test dest
+ -> do test' <- cmmExprConFold False test
+ return $ case test' of
+ CmmLit (CmmInt 0 _) ->
+ CmmComment (mkFastString ("deleted: " ++
+ showSDoc (pprStmt stmt)))
+
+ CmmLit (CmmInt n _) -> CmmBranch dest
+ other -> CmmCondBranch test' dest
+
+ CmmSwitch expr ids
+ -> do expr' <- cmmExprConFold False expr
+ return $ CmmSwitch expr' ids
+
other
- -> other
- where
- manifestlyZero (StInt 0) = True
- manifestlyZero other = False
+ -> return other
-stixExpr_ConFold expr
+
+cmmExprConFold isJumpTarget expr
= case expr of
- StInd pk addr
- -> StInd pk (stixExpr_ConFold addr)
- StCall fn cconv pk args
- -> StCall fn cconv pk (map stixExpr_ConFold args)
- StIndex pk (StIndex pk' base off) off'
- -- Fold indices together when the types match:
- | pk == pk'
- -> StIndex pk (stixExpr_ConFold base)
- (stixExpr_ConFold (StMachOp MO_Nat_Add [off, off']))
- StIndex pk base off
- -> StIndex pk (stixExpr_ConFold base) (stixExpr_ConFold off)
-
- StMachOp mop args
- -- For PrimOps, we first optimize the children, and then we try
+ CmmLoad addr rep
+ -> do addr' <- cmmExprConFold False addr
+ return $ CmmLoad addr' rep
+
+ CmmMachOp mop args
+ -- For MachOps, we first optimize the children, and then we try
-- our hand at some constant-folding.
- -> stixMachOpFold mop (map stixExpr_ConFold args)
- StReg (StixMagicId mid)
- -- Replace register leaves with appropriate StixTrees for
- -- the given target. MagicIds which map to a reg on this arch are left unchanged.
- -- For the rest, BaseReg is taken to mean the address of the reg table
- -- in MainCapability, and for all others we generate an indirection to
- -- its location in the register table.
- -> case get_MagicId_reg_or_addr mid of
- Left realreg -> expr
+ -> do args' <- mapM (cmmExprConFold False) args
+ return $ cmmMachOpFold mop args'
+
+ CmmLit (CmmLabel lbl)
+ -> cmmMakeDynamicReference addImportCmmOpt isJumpTarget lbl
+ CmmLit (CmmLabelOff lbl off)
+ -> do dynRef <- cmmMakeDynamicReference addImportCmmOpt isJumpTarget lbl
+ return $ cmmMachOpFold (MO_Add wordRep) [
+ dynRef,
+ (CmmLit $ CmmInt (fromIntegral off) wordRep)
+ ]
+
+#if powerpc_TARGET_ARCH
+ -- On powerpc (non-PIC), it's easier to jump directly to a label than
+ -- to use the register table, so we replace these registers
+ -- with the corresponding labels:
+ CmmReg (CmmGlobal GCEnter1)
+ | not opt_PIC
+ -> cmmExprConFold isJumpTarget $
+ CmmLit (CmmLabel (mkRtsCodeLabel SLIT( "__stg_gc_enter_1")))
+ CmmReg (CmmGlobal GCFun)
+ | not opt_PIC
+ -> cmmExprConFold isJumpTarget $
+ CmmLit (CmmLabel (mkRtsCodeLabel SLIT( "__stg_gc_fun")))
+#endif
+
+ CmmReg (CmmGlobal mid)
+ -- Replace register leaves with appropriate StixTrees for
+ -- the given target. MagicIds which map to a reg on this
+ -- arch are left unchanged. For the rest, BaseReg is taken
+ -- to mean the address of the reg table in MainCapability,
+ -- and for all others we generate an indirection to its
+ -- location in the register table.
+ -> case get_GlobalReg_reg_or_addr mid of
+ Left realreg -> return expr
Right baseRegAddr
-> case mid of
- BaseReg -> stixExpr_ConFold baseRegAddr
- other -> stixExpr_ConFold (StInd (magicIdPrimRep mid) baseRegAddr)
+ BaseReg -> cmmExprConFold False baseRegAddr
+ other -> cmmExprConFold False (CmmLoad baseRegAddr
+ (globalRegRep mid))
+ -- eliminate zero offsets
+ CmmRegOff reg 0
+ -> cmmExprConFold False (CmmReg reg)
+
+ CmmRegOff (CmmGlobal mid) offset
+ -- RegOf leaves are just a shorthand form. If the reg maps
+ -- to a real reg, we keep the shorthand, otherwise, we just
+ -- expand it and defer to the above code.
+ -> case get_GlobalReg_reg_or_addr mid of
+ Left realreg -> return expr
+ Right baseRegAddr
+ -> cmmExprConFold False (CmmMachOp (MO_Add wordRep) [
+ CmmReg (CmmGlobal mid),
+ CmmLit (CmmInt (fromIntegral offset)
+ wordRep)])
other
- -> other
-\end{code}
+ -> return other
-Now, try to constant-fold the PrimOps. The arguments have already
-been optimized and folded.
+-- -----------------------------------------------------------------------------
+-- Utils
-\begin{code}
-stixMachOpFold
- :: MachOp -- The operation from an StMachOp
- -> [StixExpr] -- The optimized arguments
- -> StixExpr
-
-stixMachOpFold mop arg@[StInt x]
- = case mop of
- MO_NatS_Neg -> StInt (-x)
- other -> StMachOp mop arg
-
-stixMachOpFold mop args@[StInt x, StInt y]
- = case mop of
- MO_32U_Gt -> StInt (if x > y then 1 else 0)
- MO_32U_Ge -> StInt (if x >= y then 1 else 0)
- MO_32U_Eq -> StInt (if x == y then 1 else 0)
- MO_32U_Ne -> StInt (if x /= y then 1 else 0)
- MO_32U_Lt -> StInt (if x < y then 1 else 0)
- MO_32U_Le -> StInt (if x <= y then 1 else 0)
- MO_Nat_Add -> StInt (x + y)
- MO_Nat_Sub -> StInt (x - y)
- MO_NatS_Mul -> StInt (x * y)
- MO_NatS_Quot | y /= 0 -> StInt (x `quot` y)
- MO_NatS_Rem | y /= 0 -> StInt (x `rem` y)
- MO_NatS_Gt -> StInt (if x > y then 1 else 0)
- MO_NatS_Ge -> StInt (if x >= y then 1 else 0)
- MO_Nat_Eq -> StInt (if x == y then 1 else 0)
- MO_Nat_Ne -> StInt (if x /= y then 1 else 0)
- MO_NatS_Lt -> StInt (if x < y then 1 else 0)
- MO_NatS_Le -> StInt (if x <= y then 1 else 0)
- MO_Nat_Shl | y >= 0 && y < 32 -> do_shl x y
- other -> StMachOp mop args
- where
- do_shl :: Integer -> Integer -> StixExpr
- do_shl v 0 = StInt v
- do_shl v n | n > 0 = do_shl (v*2) (n-1)
-\end{code}
+bind f x = x $! f
-When possible, shift the constants to the right-hand side, so that we
-can match for strength reductions. Note that the code generator will
-also assume that constants have been shifted to the right when
-possible.
-
-\begin{code}
-stixMachOpFold op [x@(StInt _), y] | isCommutableMachOp op
- = stixMachOpFold op [y, x]
-\end{code}
-
-We can often do something with constants of 0 and 1 ...
-
-\begin{code}
-stixMachOpFold mop args@[x, y@(StInt 0)]
- = case mop of
- MO_Nat_Add -> x
- MO_Nat_Sub -> x
- MO_NatS_Mul -> y
- MO_NatU_Mul -> y
- MO_Nat_And -> y
- MO_Nat_Or -> x
- MO_Nat_Xor -> x
- MO_Nat_Shl -> x
- MO_Nat_Shr -> x
- MO_Nat_Sar -> x
- MO_Nat_Ne | x_is_comparison -> x
- other -> StMachOp mop args
- where
- x_is_comparison
- = case x of
- StMachOp mopp [_, _] -> isComparisonMachOp mopp
- _ -> False
-
-stixMachOpFold mop args@[x, y@(StInt 1)]
- = case mop of
- MO_NatS_Mul -> x
- MO_NatU_Mul -> x
- MO_NatS_Quot -> x
- MO_NatU_Quot -> x
- MO_NatS_Rem -> StInt 0
- MO_NatU_Rem -> StInt 0
- other -> StMachOp mop args
\end{code}
-Now look for multiplication/division by powers of 2 (integers).
-
-\begin{code}
-stixMachOpFold mop args@[x, y@(StInt n)]
- = case mop of
- MO_NatS_Mul
- -> case exactLog2 n of
- Nothing -> unchanged
- Just p -> StMachOp MO_Nat_Shl [x, StInt p]
- MO_NatS_Quot
- -> case exactLog2 n of
- Nothing -> unchanged
- Just p -> StMachOp MO_Nat_Shr [x, StInt p]
- other
- -> unchanged
- where
- unchanged = StMachOp mop args
-\end{code}
-
-Anything else is just too hard.
-
-\begin{code}
-stixMachOpFold mop args = StMachOp mop args
-\end{code}
projects / ghc-hetmet.git / blobdiff