1 -- -----------------------------------------------------------------------------
3 -- (c) The University of Glasgow 1993-2004
5 -- This is the top-level module in the native code generator.
7 -- -----------------------------------------------------------------------------
10 module AsmCodeGen ( nativeCodeGen ) where
12 #include "HsVersions.h"
13 #include "nativeGen/NCG.h"
21 import PositionIndependentCode
26 import qualified RegAllocColor as Color
27 import qualified GraphColor as Color
30 import CmmOpt ( cmmMiniInline, cmmMachOpFold )
31 import PprCmm ( pprStmt, pprCmms, pprCmm )
36 import Unique ( Unique, getUnique )
39 import List ( groupBy, sortBy )
40 import ErrUtils ( dumpIfSet_dyn )
42 import StaticFlags ( opt_Static, opt_PIC )
44 import Config ( cProjectVersion )
48 import qualified Pretty
65 The native-code generator has machine-independent and
66 machine-dependent modules.
68 This module ("AsmCodeGen") is the top-level machine-independent
69 module. Before entering machine-dependent land, we do some
70 machine-independent optimisations (defined below) on the
73 We convert to the machine-specific 'Instr' datatype with
74 'cmmCodeGen', assuming an infinite supply of registers. We then use
75 a machine-independent register allocator ('regAlloc') to rejoin
76 reality. Obviously, 'regAlloc' has machine-specific helper
77 functions (see about "RegAllocInfo" below).
79 Finally, we order the basic blocks of the function so as to minimise
80 the number of jumps between blocks, by utilising fallthrough wherever
83 The machine-dependent bits break down as follows:
85 * ["MachRegs"] Everything about the target platform's machine
86 registers (and immediate operands, and addresses, which tend to
87 intermingle/interact with registers).
89 * ["MachInstrs"] Includes the 'Instr' datatype (possibly should
90 have a module of its own), plus a miscellany of other things
91 (e.g., 'targetDoubleSize', 'smStablePtrTable', ...)
93 * ["MachCodeGen"] is where 'Cmm' stuff turns into
96 * ["PprMach"] 'pprInstr' turns an 'Instr' into text (well, really
99 * ["RegAllocInfo"] In the register allocator, we manipulate
100 'MRegsState's, which are 'BitSet's, one bit per machine register.
101 When we want to say something about a specific machine register
102 (e.g., ``it gets clobbered by this instruction''), we set/unset
103 its bit. Obviously, we do this 'BitSet' thing for efficiency
106 The 'RegAllocInfo' module collects together the machine-specific
107 info needed to do register allocation.
109 * ["RegisterAlloc"] The (machine-independent) register allocator.
112 -- -----------------------------------------------------------------------------
113 -- Top-level of the native codegen
115 -- NB. We *lazilly* compile each block of code for space reasons.
118 nativeCodeGen :: DynFlags -> Module -> ModLocation -> [RawCmm] -> UniqSupply -> IO Pretty.Doc
119 nativeCodeGen dflags mod modLocation cmms us
120 = let (res, _) = initUs us $
121 cgCmm (concat (map add_split cmms))
123 cgCmm :: [RawCmmTop] -> UniqSM ( [CmmNativeGenDump], Pretty.Doc, [CLabel])
125 lazyMapUs (cmmNativeGen dflags) tops `thenUs` \ results ->
126 case unzip3 results of { (dump,docs,imps) ->
127 returnUs (dump, my_vcat docs, concat imps)
130 case res of { (dump, insn_sdoc, imports) -> do
132 cmmNativeGenDump dflags mod modLocation dump
134 return (insn_sdoc Pretty.$$ dyld_stubs imports
136 #if HAVE_SUBSECTIONS_VIA_SYMBOLS
137 -- On recent versions of Darwin, the linker supports
138 -- dead-stripping of code and data on a per-symbol basis.
139 -- There's a hack to make this work in PprMach.pprNatCmmTop.
140 Pretty.$$ Pretty.text ".subsections_via_symbols"
142 #if HAVE_GNU_NONEXEC_STACK
143 -- On recent GNU ELF systems one can mark an object file
144 -- as not requiring an executable stack. If all objects
145 -- linked into a program have this note then the program
146 -- will not use an executable stack, which is good for
147 -- security. GHC generated code does not need an executable
148 -- stack so add the note in:
149 Pretty.$$ Pretty.text ".section .note.GNU-stack,\"\",@progbits"
151 #if !defined(darwin_TARGET_OS)
152 -- And just because every other compiler does, lets stick in
153 -- an identifier directive: .ident "GHC x.y.z"
154 Pretty.$$ let compilerIdent = Pretty.text "GHC" Pretty.<+>
155 Pretty.text cProjectVersion
156 in Pretty.text ".ident" Pretty.<+>
157 Pretty.doubleQuotes compilerIdent
165 | dopt Opt_SplitObjs dflags = split_marker : tops
168 split_marker = CmmProc [] mkSplitMarkerLabel [] []
170 -- Generate "symbol stubs" for all external symbols that might
171 -- come from a dynamic library.
172 {- dyld_stubs imps = Pretty.vcat $ map pprDyldSymbolStub $
173 map head $ group $ sort imps-}
175 -- (Hack) sometimes two Labels pretty-print the same, but have
176 -- different uniques; so we compare their text versions...
178 | needImportedSymbols
180 (pprGotDeclaration :) $
181 map (pprImportedSymbol . fst . head) $
182 groupBy (\(_,a) (_,b) -> a == b) $
183 sortBy (\(_,a) (_,b) -> compare a b) $
189 where doPpr lbl = (lbl, Pretty.render $ pprCLabel lbl astyle)
190 astyle = mkCodeStyle AsmStyle
193 my_vcat sds = Pretty.vcat sds
195 my_vcat sds = Pretty.vcat (
198 Pretty.$$ Pretty.ptext SLIT("# ___ncg_debug_marker")
199 Pretty.$$ Pretty.char ' '
206 -- Carries output of the code generator passes, for dumping.
207 -- Make sure to only fill the one's we're interested in to avoid
208 -- creating space leaks.
210 data CmmNativeGenDump
212 { cdCmmOpt :: RawCmmTop
213 , cdNative :: [NatCmmTop]
214 , cdLiveness :: [LiveCmmTop]
215 , cdCoalesce :: Maybe [LiveCmmTop]
216 , cdRegAllocStats :: Maybe [RegAllocStats]
217 , cdColoredGraph :: Maybe (Color.Graph Reg RegClass Reg)
218 , cdAlloced :: [NatCmmTop] }
220 dchoose dflags opt a b
221 | dopt opt dflags = a
224 dchooses dflags opts a b
225 | or $ map ( (flip dopt) dflags) opts = a
228 -- | Complete native code generation phase for a single top-level chunk of Cmm.
229 -- Unless they're being dumped, intermediate data structures are squashed after
230 -- every stage to avoid creating space leaks.
232 cmmNativeGen :: DynFlags -> RawCmmTop -> UniqSM (CmmNativeGenDump, Pretty.Doc, [CLabel])
233 cmmNativeGen dflags cmm
237 <- {-# SCC "fixAssigns" #-}
240 ---- cmm to cmm optimisations
241 (cmm, imports, ppr_cmm)
243 -> {-# SCC "genericOpt" #-}
244 do let (cmm, imports) = cmmToCmm dflags fixed_cmm
248 , dchoose dflags Opt_D_dump_cmm cmm (CmmData Text []))
252 ---- generate native code from cmm
253 (native, lastMinuteImports, ppr_native)
255 -> {-# SCC "genMachCode" #-}
256 do (machCode, lastMinuteImports)
257 <- genMachCode dflags cmm
261 , dchoose dflags Opt_D_dump_asm_native machCode [])
265 ---- tag instructions with register liveness information
266 (withLiveness, ppr_withLiveness)
268 -> {-# SCC "regLiveness" #-}
270 withLiveness <- mapUs regLiveness native
272 return ( withLiveness
273 , dchoose dflags Opt_D_dump_asm_liveness withLiveness []))
276 ---- allocate registers
277 (alloced, ppr_alloced, ppr_coalesce, ppr_regAllocStats, ppr_coloredGraph)
279 -> {-# SCC "regAlloc" #-}
281 if dopt Opt_RegsGraph dflags
283 -- the regs usable for allocation
285 = foldr (\r -> plusUFM_C unionUniqSets
286 $ unitUFM (regClass r) (unitUniqSet r))
288 $ map RealReg allocatableRegs
290 -- aggressively coalesce moves between virtual regs
291 coalesced <- regCoalesce withLiveness
293 -- graph coloring register allocation
294 (alloced, regAllocStats)
297 (mkUniqSet [0..maxSpillSlots])
301 , dchoose dflags Opt_D_dump_asm_regalloc alloced []
302 , dchoose dflags Opt_D_dump_asm_coalesce (Just coalesced) Nothing
304 [ Opt_D_dump_asm_regalloc_stages
305 , Opt_D_drop_asm_stats]
306 (Just regAllocStats) Nothing
307 , dchoose dflags Opt_D_dump_asm_conflicts Nothing Nothing)
310 -- do linear register allocation
311 alloced <- mapUs regAlloc withLiveness
313 , dchoose dflags Opt_D_dump_asm_regalloc alloced []
320 ---- shortcut branches
322 {-# SCC "shortcutBranches" #-}
323 shortcutBranches dflags alloced
327 {-# SCC "sequenceBlocks" #-}
328 map sequenceTop shorted
331 let final_mach_code =
333 {-# SCC "x86fp_kludge" #-}
334 map x86fp_kludge sequenced
342 Pretty.vcat (map pprNatCmmTop final_mach_code)
347 , cdNative = ppr_native
348 , cdLiveness = ppr_withLiveness
349 , cdCoalesce = ppr_coalesce
350 , cdRegAllocStats = ppr_regAllocStats
351 , cdColoredGraph = ppr_coloredGraph
352 , cdAlloced = ppr_alloced }
354 returnUs (dump, final_sdoc Pretty.$$ Pretty.text "", lastMinuteImports ++ imports)
357 x86fp_kludge :: NatCmmTop -> NatCmmTop
358 x86fp_kludge top@(CmmData _ _) = top
359 x86fp_kludge top@(CmmProc info lbl params code) =
360 CmmProc info lbl params (map bb_i386_insert_ffrees code)
362 bb_i386_insert_ffrees (BasicBlock id instrs) =
363 BasicBlock id (i386_insert_ffrees instrs)
367 -- Dump output of native code generator passes
368 -- stripe across the outputs for each block so all the information for a
369 -- certain stage is concurrent in the dumps.
371 cmmNativeGenDump :: DynFlags -> Module -> ModLocation -> [CmmNativeGenDump] -> IO ()
372 cmmNativeGenDump dflags mod modLocation dump
375 Opt_D_dump_opt_cmm "Optimised Cmm"
376 (pprCmm $ Cmm $ map cdCmmOpt dump)
379 Opt_D_dump_asm_native "Native code"
380 (vcat $ map (docToSDoc . pprNatCmmTop) $ concatMap cdNative dump)
383 Opt_D_dump_asm_liveness "Liveness annotations added"
384 (vcat $ map (ppr . cdLiveness) dump)
387 Opt_D_dump_asm_coalesce "Reg-Reg moves coalesced"
388 (vcat $ map (fromMaybe empty . liftM ppr . cdCoalesce) dump)
391 Opt_D_dump_asm_regalloc "Registers allocated"
392 (vcat $ map (docToSDoc . pprNatCmmTop) $ concatMap cdAlloced dump)
394 -- with the graph coloring allocator, show the result of each build/spill stage
395 -- for each block in turn.
396 when (dopt Opt_D_dump_asm_regalloc_stages dflags)
399 $ vcat $ map (\(stage, stats) ->
400 text "-- Stage " <> int stage
403 $ map (fromMaybe [] . cdRegAllocStats) dump
405 -- Build a global register conflict graph.
406 -- If you want to see the graph for just one basic block then use asm-regalloc-stages instead.
408 Opt_D_dump_asm_conflicts "Register conflict graph"
409 $ Color.dotGraph Color.regDotColor trivColorable
410 $ foldl Color.union Color.initGraph
411 $ catMaybes $ map cdColoredGraph dump
413 -- Drop native code generator statistics.
414 -- This is potentially a large amount of information, and we want to be able
415 -- to collect it while running nofib. Drop a new file instead of emitting
416 -- it to stdout/stderr.
418 when (dopt Opt_D_drop_asm_stats dflags)
419 $ do -- make the drop file name based on the object file name
420 let dropFile = (init $ ml_obj_file modLocation) ++ "drop-asm-stats"
422 -- slurp out all the regalloc stats
423 let stats = concat $ catMaybes $ map cdRegAllocStats dump
425 -- build a global conflict graph
426 let graph = foldl Color.union Color.initGraph $ map raGraph stats
428 -- pretty print the various sections and write out the file.
429 let outSpills = pprStatsSpills stats
430 let outLife = pprStatsLifetimes stats
431 let outConflict = pprStatsConflict stats
432 let outScatter = pprStatsLifeConflict stats graph
435 (showSDoc $ vcat [outSpills, outLife, outConflict, outScatter])
439 -- -----------------------------------------------------------------------------
440 -- Sequencing the basic blocks
442 -- Cmm BasicBlocks are self-contained entities: they always end in a
443 -- jump, either non-local or to another basic block in the same proc.
444 -- In this phase, we attempt to place the basic blocks in a sequence
445 -- such that as many of the local jumps as possible turn into
448 sequenceTop :: NatCmmTop -> NatCmmTop
449 sequenceTop top@(CmmData _ _) = top
450 sequenceTop (CmmProc info lbl params blocks) =
451 CmmProc info lbl params (makeFarBranches $ sequenceBlocks blocks)
453 -- The algorithm is very simple (and stupid): we make a graph out of
454 -- the blocks where there is an edge from one block to another iff the
455 -- first block ends by jumping to the second. Then we topologically
456 -- sort this graph. Then traverse the list: for each block, we first
457 -- output the block, then if it has an out edge, we move the
458 -- destination of the out edge to the front of the list, and continue.
460 sequenceBlocks :: [NatBasicBlock] -> [NatBasicBlock]
461 sequenceBlocks [] = []
462 sequenceBlocks (entry:blocks) =
463 seqBlocks (mkNode entry : reverse (flattenSCCs (sccBlocks blocks)))
464 -- the first block is the entry point ==> it must remain at the start.
466 sccBlocks :: [NatBasicBlock] -> [SCC (NatBasicBlock,Unique,[Unique])]
467 sccBlocks blocks = stronglyConnCompR (map mkNode blocks)
469 getOutEdges :: [Instr] -> [Unique]
470 getOutEdges instrs = case jumpDests (last instrs) [] of
471 [one] -> [getUnique one]
473 -- we're only interested in the last instruction of
474 -- the block, and only if it has a single destination.
476 mkNode block@(BasicBlock id instrs) = (block, getUnique id, getOutEdges instrs)
479 seqBlocks ((block,_,[]) : rest)
480 = block : seqBlocks rest
481 seqBlocks ((block@(BasicBlock id instrs),_,[next]) : rest)
482 | can_fallthrough = BasicBlock id (init instrs) : seqBlocks rest'
483 | otherwise = block : seqBlocks rest'
485 (can_fallthrough, rest') = reorder next [] rest
486 -- TODO: we should do a better job for cycles; try to maximise the
487 -- fallthroughs within a loop.
488 seqBlocks _ = panic "AsmCodegen:seqBlocks"
490 reorder id accum [] = (False, reverse accum)
491 reorder id accum (b@(block,id',out) : rest)
492 | id == id' = (True, (block,id,out) : reverse accum ++ rest)
493 | otherwise = reorder id (b:accum) rest
496 -- -----------------------------------------------------------------------------
497 -- Making far branches
499 -- Conditional branches on PowerPC are limited to +-32KB; if our Procs get too
500 -- big, we have to work around this limitation.
502 makeFarBranches :: [NatBasicBlock] -> [NatBasicBlock]
504 #if powerpc_TARGET_ARCH
505 makeFarBranches blocks
506 | last blockAddresses < nearLimit = blocks
507 | otherwise = zipWith handleBlock blockAddresses blocks
509 blockAddresses = scanl (+) 0 $ map blockLen blocks
510 blockLen (BasicBlock _ instrs) = length instrs
512 handleBlock addr (BasicBlock id instrs)
513 = BasicBlock id (zipWith makeFar [addr..] instrs)
515 makeFar addr (BCC ALWAYS tgt) = BCC ALWAYS tgt
516 makeFar addr (BCC cond tgt)
517 | abs (addr - targetAddr) >= nearLimit
521 where Just targetAddr = lookupUFM blockAddressMap tgt
522 makeFar addr other = other
524 nearLimit = 7000 -- 8192 instructions are allowed; let's keep some
525 -- distance, as we have a few pseudo-insns that are
526 -- pretty-printed as multiple instructions,
527 -- and it's just not worth the effort to calculate
530 blockAddressMap = listToUFM $ zip (map blockId blocks) blockAddresses
535 -- -----------------------------------------------------------------------------
538 shortcutBranches :: DynFlags -> [NatCmmTop] -> [NatCmmTop]
539 shortcutBranches dflags tops
540 | optLevel dflags < 1 = tops -- only with -O or higher
541 | otherwise = map (apply_mapping mapping) tops'
543 (tops', mappings) = mapAndUnzip build_mapping tops
544 mapping = foldr plusUFM emptyUFM mappings
546 build_mapping top@(CmmData _ _) = (top, emptyUFM)
547 build_mapping (CmmProc info lbl params [])
548 = (CmmProc info lbl params [], emptyUFM)
549 build_mapping (CmmProc info lbl params (head:blocks))
550 = (CmmProc info lbl params (head:others), mapping)
551 -- drop the shorted blocks, but don't ever drop the first one,
552 -- because it is pointed to by a global label.
554 -- find all the blocks that just consist of a jump that can be
556 (shortcut_blocks, others) = partitionWith split blocks
557 split (BasicBlock id [insn]) | Just dest <- canShortcut insn
559 split other = Right other
561 -- build a mapping from BlockId to JumpDest for shorting branches
562 mapping = foldl add emptyUFM shortcut_blocks
563 add ufm (id,dest) = addToUFM ufm id dest
565 apply_mapping ufm (CmmData sec statics)
566 = CmmData sec (map (shortcutStatic (lookupUFM ufm)) statics)
567 -- we need to get the jump tables, so apply the mapping to the entries
569 apply_mapping ufm (CmmProc info lbl params blocks)
570 = CmmProc info lbl params (map short_bb blocks)
572 short_bb (BasicBlock id insns) = BasicBlock id $! map short_insn insns
573 short_insn i = shortcutJump (lookupUFM ufm) i
574 -- shortcutJump should apply the mapping repeatedly,
575 -- just in case we can short multiple branches.
577 -- -----------------------------------------------------------------------------
578 -- Instruction selection
580 -- Native code instruction selection for a chunk of stix code. For
581 -- this part of the computation, we switch from the UniqSM monad to
582 -- the NatM monad. The latter carries not only a Unique, but also an
583 -- Int denoting the current C stack pointer offset in the generated
584 -- code; this is needed for creating correct spill offsets on
585 -- architectures which don't offer, or for which it would be
586 -- prohibitively expensive to employ, a frame pointer register. Viz,
589 -- The offset is measured in bytes, and indicates the difference
590 -- between the current (simulated) C stack-ptr and the value it was at
591 -- the beginning of the block. For stacks which grow down, this value
592 -- should be either zero or negative.
594 -- Switching between the two monads whilst carrying along the same
595 -- Unique supply breaks abstraction. Is that bad?
597 genMachCode :: DynFlags -> RawCmmTop -> UniqSM ([NatCmmTop], [CLabel])
599 genMachCode dflags cmm_top
600 = do { initial_us <- getUs
601 ; let initial_st = mkNatM_State initial_us 0 dflags
602 (new_tops, final_st) = initNat initial_st (cmmTopCodeGen cmm_top)
603 final_delta = natm_delta final_st
604 final_imports = natm_imports final_st
605 ; if final_delta == 0
606 then return (new_tops, final_imports)
607 else pprPanic "genMachCode: nonzero final delta" (int final_delta)
610 -- -----------------------------------------------------------------------------
611 -- Fixup assignments to global registers so that they assign to
612 -- locations within the RegTable, if appropriate.
614 -- Note that we currently don't fixup reads here: they're done by
615 -- the generic optimiser below, to avoid having two separate passes
618 fixAssignsTop :: RawCmmTop -> UniqSM RawCmmTop
619 fixAssignsTop top@(CmmData _ _) = returnUs top
620 fixAssignsTop (CmmProc info lbl params blocks) =
621 mapUs fixAssignsBlock blocks `thenUs` \ blocks' ->
622 returnUs (CmmProc info lbl params blocks')
624 fixAssignsBlock :: CmmBasicBlock -> UniqSM CmmBasicBlock
625 fixAssignsBlock (BasicBlock id stmts) =
626 fixAssigns stmts `thenUs` \ stmts' ->
627 returnUs (BasicBlock id stmts')
629 fixAssigns :: [CmmStmt] -> UniqSM [CmmStmt]
631 mapUs fixAssign stmts `thenUs` \ stmtss ->
632 returnUs (concat stmtss)
634 fixAssign :: CmmStmt -> UniqSM [CmmStmt]
635 fixAssign (CmmAssign (CmmGlobal reg) src)
636 | Left realreg <- reg_or_addr
637 = returnUs [CmmAssign (CmmGlobal reg) src]
638 | Right baseRegAddr <- reg_or_addr
639 = returnUs [CmmStore baseRegAddr src]
640 -- Replace register leaves with appropriate StixTrees for
641 -- the given target. GlobalRegs which map to a reg on this
642 -- arch are left unchanged. Assigning to BaseReg is always
643 -- illegal, so we check for that.
645 reg_or_addr = get_GlobalReg_reg_or_addr reg
647 fixAssign other_stmt = returnUs [other_stmt]
649 -- -----------------------------------------------------------------------------
650 -- Generic Cmm optimiser
656 (b) Simple inlining: a temporary which is assigned to and then
657 used, once, can be shorted.
658 (c) Replacement of references to GlobalRegs which do not have
659 machine registers by the appropriate memory load (eg.
660 Hp ==> *(BaseReg + 34) ).
661 (d) Position independent code and dynamic linking
662 (i) introduce the appropriate indirections
663 and position independent refs
664 (ii) compile a list of imported symbols
666 Ideas for other things we could do (ToDo):
668 - shortcut jumps-to-jumps
669 - eliminate dead code blocks
670 - simple CSE: if an expr is assigned to a temp, then replace later occs of
671 that expr with the temp, until the expr is no longer valid (can push through
672 temp assignments, and certain assigns to mem...)
675 cmmToCmm :: DynFlags -> RawCmmTop -> (RawCmmTop, [CLabel])
676 cmmToCmm _ top@(CmmData _ _) = (top, [])
677 cmmToCmm dflags (CmmProc info lbl params blocks) = runCmmOpt dflags $ do
678 blocks' <- mapM cmmBlockConFold (cmmMiniInline blocks)
679 return $ CmmProc info lbl params blocks'
681 newtype CmmOptM a = CmmOptM (([CLabel], DynFlags) -> (# a, [CLabel] #))
683 instance Monad CmmOptM where
684 return x = CmmOptM $ \(imports, _) -> (# x,imports #)
686 CmmOptM $ \(imports, dflags) ->
687 case f (imports, dflags) of
690 CmmOptM g' -> g' (imports', dflags)
692 addImportCmmOpt :: CLabel -> CmmOptM ()
693 addImportCmmOpt lbl = CmmOptM $ \(imports, dflags) -> (# (), lbl:imports #)
695 getDynFlagsCmmOpt :: CmmOptM DynFlags
696 getDynFlagsCmmOpt = CmmOptM $ \(imports, dflags) -> (# dflags, imports #)
698 runCmmOpt :: DynFlags -> CmmOptM a -> (a, [CLabel])
699 runCmmOpt dflags (CmmOptM f) = case f ([], dflags) of
700 (# result, imports #) -> (result, imports)
702 cmmBlockConFold :: CmmBasicBlock -> CmmOptM CmmBasicBlock
703 cmmBlockConFold (BasicBlock id stmts) = do
704 stmts' <- mapM cmmStmtConFold stmts
705 return $ BasicBlock id stmts'
710 -> do src' <- cmmExprConFold DataReference src
711 return $ case src' of
712 CmmReg reg' | reg == reg' -> CmmNop
713 new_src -> CmmAssign reg new_src
716 -> do addr' <- cmmExprConFold DataReference addr
717 src' <- cmmExprConFold DataReference src
718 return $ CmmStore addr' src'
721 -> do addr' <- cmmExprConFold JumpReference addr
722 return $ CmmJump addr' regs
724 CmmCall target regs args srt returns
725 -> do target' <- case target of
726 CmmCallee e conv -> do
727 e' <- cmmExprConFold CallReference e
728 return $ CmmCallee e' conv
729 other -> return other
730 args' <- mapM (\(arg, hint) -> do
731 arg' <- cmmExprConFold DataReference arg
732 return (arg', hint)) args
733 return $ CmmCall target' regs args' srt returns
735 CmmCondBranch test dest
736 -> do test' <- cmmExprConFold DataReference test
737 return $ case test' of
738 CmmLit (CmmInt 0 _) ->
739 CmmComment (mkFastString ("deleted: " ++
740 showSDoc (pprStmt stmt)))
742 CmmLit (CmmInt n _) -> CmmBranch dest
743 other -> CmmCondBranch test' dest
746 -> do expr' <- cmmExprConFold DataReference expr
747 return $ CmmSwitch expr' ids
753 cmmExprConFold referenceKind expr
756 -> do addr' <- cmmExprConFold DataReference addr
757 return $ CmmLoad addr' rep
760 -- For MachOps, we first optimize the children, and then we try
761 -- our hand at some constant-folding.
762 -> do args' <- mapM (cmmExprConFold DataReference) args
763 return $ cmmMachOpFold mop args'
765 CmmLit (CmmLabel lbl)
767 dflags <- getDynFlagsCmmOpt
768 cmmMakeDynamicReference dflags addImportCmmOpt referenceKind lbl
769 CmmLit (CmmLabelOff lbl off)
771 dflags <- getDynFlagsCmmOpt
772 dynRef <- cmmMakeDynamicReference dflags addImportCmmOpt referenceKind lbl
773 return $ cmmMachOpFold (MO_Add wordRep) [
775 (CmmLit $ CmmInt (fromIntegral off) wordRep)
778 #if powerpc_TARGET_ARCH
779 -- On powerpc (non-PIC), it's easier to jump directly to a label than
780 -- to use the register table, so we replace these registers
781 -- with the corresponding labels:
782 CmmReg (CmmGlobal GCEnter1)
784 -> cmmExprConFold referenceKind $
785 CmmLit (CmmLabel (mkRtsCodeLabel SLIT( "__stg_gc_enter_1")))
786 CmmReg (CmmGlobal GCFun)
788 -> cmmExprConFold referenceKind $
789 CmmLit (CmmLabel (mkRtsCodeLabel SLIT( "__stg_gc_fun")))
792 CmmReg (CmmGlobal mid)
793 -- Replace register leaves with appropriate StixTrees for
794 -- the given target. MagicIds which map to a reg on this
795 -- arch are left unchanged. For the rest, BaseReg is taken
796 -- to mean the address of the reg table in MainCapability,
797 -- and for all others we generate an indirection to its
798 -- location in the register table.
799 -> case get_GlobalReg_reg_or_addr mid of
800 Left realreg -> return expr
803 BaseReg -> cmmExprConFold DataReference baseRegAddr
804 other -> cmmExprConFold DataReference
805 (CmmLoad baseRegAddr (globalRegRep mid))
806 -- eliminate zero offsets
808 -> cmmExprConFold referenceKind (CmmReg reg)
810 CmmRegOff (CmmGlobal mid) offset
811 -- RegOf leaves are just a shorthand form. If the reg maps
812 -- to a real reg, we keep the shorthand, otherwise, we just
813 -- expand it and defer to the above code.
814 -> case get_GlobalReg_reg_or_addr mid of
815 Left realreg -> return expr
817 -> cmmExprConFold DataReference (CmmMachOp (MO_Add wordRep) [
818 CmmReg (CmmGlobal mid),
819 CmmLit (CmmInt (fromIntegral offset)
824 -- -----------------------------------------------------------------------------