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
376 Opt_D_dump_opt_cmm "Optimised Cmm"
377 (pprCmm $ Cmm $ map cdCmmOpt dump)
380 Opt_D_dump_asm_native "(asm-native) Native code"
381 (vcat $ map (docToSDoc . pprNatCmmTop) $ concatMap cdNative dump)
384 Opt_D_dump_asm_liveness "(asm-liveness) Liveness info added"
385 (vcat $ map (ppr . cdLiveness) dump)
388 Opt_D_dump_asm_coalesce "(asm-coalesce) Register moves coalesced."
389 (vcat $ map (ppr . (\(Just c) -> c) . cdCoalesce) dump)
392 Opt_D_dump_asm_regalloc "(asm-regalloc) Registers allocated"
393 (vcat $ map (docToSDoc . pprNatCmmTop) $ concatMap cdAlloced dump)
395 -- with the graph coloring allocator, show the result of each build/spill stage
396 -- for each block in turn.
398 -> dumpIfSet_dyn dflags
399 Opt_D_dump_asm_regalloc_stages "(asm-regalloc-stages)"
400 (vcat $ map (\(stage, stats) ->
401 text "-- Stage " <> int stage
403 (zip [0..] codeGraphs)))
404 $ map ((\(Just c) -> c) . cdRegAllocStats) dump
407 -- Build a global register conflict graph.
408 -- If you want to see the graph for just one basic block then use asm-regalloc-stages instead.
410 Opt_D_dump_asm_conflicts "(asm-conflicts) Register conflict graph"
411 $ Color.dotGraph Color.regDotColor trivColorable
412 $ foldl Color.union Color.initGraph
413 $ catMaybes $ map cdColoredGraph dump
416 -- Drop native code gen statistics.
417 -- This is potentially a large amount of information, so we make a new file instead
418 -- of dumping it to stdout.
419 when (dopt Opt_D_drop_asm_stats dflags)
420 $ do -- make the drop file name based on the object file name
421 let dropFile = (init $ ml_obj_file modLocation) ++ "drop-asm-stats"
423 -- slurp out all the regalloc stats
424 let stats = concat $ catMaybes $ map cdRegAllocStats dump
426 -- build a global conflict graph
427 let graph = foldl Color.union Color.initGraph $ map raGraph stats
429 -- pretty print the various sections and write out the file.
430 let outSpills = pprStatsSpills stats
431 let outLife = pprStatsLifetimes stats
432 let outConflict = pprStatsConflict stats
433 let outScatter = pprStatsLifeConflict stats graph
436 (showSDoc $ vcat [outSpills, outLife, outConflict, outScatter])
442 -- -----------------------------------------------------------------------------
443 -- Sequencing the basic blocks
445 -- Cmm BasicBlocks are self-contained entities: they always end in a
446 -- jump, either non-local or to another basic block in the same proc.
447 -- In this phase, we attempt to place the basic blocks in a sequence
448 -- such that as many of the local jumps as possible turn into
451 sequenceTop :: NatCmmTop -> NatCmmTop
452 sequenceTop top@(CmmData _ _) = top
453 sequenceTop (CmmProc info lbl params blocks) =
454 CmmProc info lbl params (makeFarBranches $ sequenceBlocks blocks)
456 -- The algorithm is very simple (and stupid): we make a graph out of
457 -- the blocks where there is an edge from one block to another iff the
458 -- first block ends by jumping to the second. Then we topologically
459 -- sort this graph. Then traverse the list: for each block, we first
460 -- output the block, then if it has an out edge, we move the
461 -- destination of the out edge to the front of the list, and continue.
463 sequenceBlocks :: [NatBasicBlock] -> [NatBasicBlock]
464 sequenceBlocks [] = []
465 sequenceBlocks (entry:blocks) =
466 seqBlocks (mkNode entry : reverse (flattenSCCs (sccBlocks blocks)))
467 -- the first block is the entry point ==> it must remain at the start.
469 sccBlocks :: [NatBasicBlock] -> [SCC (NatBasicBlock,Unique,[Unique])]
470 sccBlocks blocks = stronglyConnCompR (map mkNode blocks)
472 getOutEdges :: [Instr] -> [Unique]
473 getOutEdges instrs = case jumpDests (last instrs) [] of
474 [one] -> [getUnique one]
476 -- we're only interested in the last instruction of
477 -- the block, and only if it has a single destination.
479 mkNode block@(BasicBlock id instrs) = (block, getUnique id, getOutEdges instrs)
482 seqBlocks ((block,_,[]) : rest)
483 = block : seqBlocks rest
484 seqBlocks ((block@(BasicBlock id instrs),_,[next]) : rest)
485 | can_fallthrough = BasicBlock id (init instrs) : seqBlocks rest'
486 | otherwise = block : seqBlocks rest'
488 (can_fallthrough, rest') = reorder next [] rest
489 -- TODO: we should do a better job for cycles; try to maximise the
490 -- fallthroughs within a loop.
491 seqBlocks _ = panic "AsmCodegen:seqBlocks"
493 reorder id accum [] = (False, reverse accum)
494 reorder id accum (b@(block,id',out) : rest)
495 | id == id' = (True, (block,id,out) : reverse accum ++ rest)
496 | otherwise = reorder id (b:accum) rest
499 -- -----------------------------------------------------------------------------
500 -- Making far branches
502 -- Conditional branches on PowerPC are limited to +-32KB; if our Procs get too
503 -- big, we have to work around this limitation.
505 makeFarBranches :: [NatBasicBlock] -> [NatBasicBlock]
507 #if powerpc_TARGET_ARCH
508 makeFarBranches blocks
509 | last blockAddresses < nearLimit = blocks
510 | otherwise = zipWith handleBlock blockAddresses blocks
512 blockAddresses = scanl (+) 0 $ map blockLen blocks
513 blockLen (BasicBlock _ instrs) = length instrs
515 handleBlock addr (BasicBlock id instrs)
516 = BasicBlock id (zipWith makeFar [addr..] instrs)
518 makeFar addr (BCC ALWAYS tgt) = BCC ALWAYS tgt
519 makeFar addr (BCC cond tgt)
520 | abs (addr - targetAddr) >= nearLimit
524 where Just targetAddr = lookupUFM blockAddressMap tgt
525 makeFar addr other = other
527 nearLimit = 7000 -- 8192 instructions are allowed; let's keep some
528 -- distance, as we have a few pseudo-insns that are
529 -- pretty-printed as multiple instructions,
530 -- and it's just not worth the effort to calculate
533 blockAddressMap = listToUFM $ zip (map blockId blocks) blockAddresses
538 -- -----------------------------------------------------------------------------
541 shortcutBranches :: DynFlags -> [NatCmmTop] -> [NatCmmTop]
542 shortcutBranches dflags tops
543 | optLevel dflags < 1 = tops -- only with -O or higher
544 | otherwise = map (apply_mapping mapping) tops'
546 (tops', mappings) = mapAndUnzip build_mapping tops
547 mapping = foldr plusUFM emptyUFM mappings
549 build_mapping top@(CmmData _ _) = (top, emptyUFM)
550 build_mapping (CmmProc info lbl params [])
551 = (CmmProc info lbl params [], emptyUFM)
552 build_mapping (CmmProc info lbl params (head:blocks))
553 = (CmmProc info lbl params (head:others), mapping)
554 -- drop the shorted blocks, but don't ever drop the first one,
555 -- because it is pointed to by a global label.
557 -- find all the blocks that just consist of a jump that can be
559 (shortcut_blocks, others) = partitionWith split blocks
560 split (BasicBlock id [insn]) | Just dest <- canShortcut insn
562 split other = Right other
564 -- build a mapping from BlockId to JumpDest for shorting branches
565 mapping = foldl add emptyUFM shortcut_blocks
566 add ufm (id,dest) = addToUFM ufm id dest
568 apply_mapping ufm (CmmData sec statics)
569 = CmmData sec (map (shortcutStatic (lookupUFM ufm)) statics)
570 -- we need to get the jump tables, so apply the mapping to the entries
572 apply_mapping ufm (CmmProc info lbl params blocks)
573 = CmmProc info lbl params (map short_bb blocks)
575 short_bb (BasicBlock id insns) = BasicBlock id $! map short_insn insns
576 short_insn i = shortcutJump (lookupUFM ufm) i
577 -- shortcutJump should apply the mapping repeatedly,
578 -- just in case we can short multiple branches.
580 -- -----------------------------------------------------------------------------
581 -- Instruction selection
583 -- Native code instruction selection for a chunk of stix code. For
584 -- this part of the computation, we switch from the UniqSM monad to
585 -- the NatM monad. The latter carries not only a Unique, but also an
586 -- Int denoting the current C stack pointer offset in the generated
587 -- code; this is needed for creating correct spill offsets on
588 -- architectures which don't offer, or for which it would be
589 -- prohibitively expensive to employ, a frame pointer register. Viz,
592 -- The offset is measured in bytes, and indicates the difference
593 -- between the current (simulated) C stack-ptr and the value it was at
594 -- the beginning of the block. For stacks which grow down, this value
595 -- should be either zero or negative.
597 -- Switching between the two monads whilst carrying along the same
598 -- Unique supply breaks abstraction. Is that bad?
600 genMachCode :: DynFlags -> RawCmmTop -> UniqSM ([NatCmmTop], [CLabel])
602 genMachCode dflags cmm_top
603 = do { initial_us <- getUs
604 ; let initial_st = mkNatM_State initial_us 0 dflags
605 (new_tops, final_st) = initNat initial_st (cmmTopCodeGen cmm_top)
606 final_delta = natm_delta final_st
607 final_imports = natm_imports final_st
608 ; if final_delta == 0
609 then return (new_tops, final_imports)
610 else pprPanic "genMachCode: nonzero final delta" (int final_delta)
613 -- -----------------------------------------------------------------------------
614 -- Fixup assignments to global registers so that they assign to
615 -- locations within the RegTable, if appropriate.
617 -- Note that we currently don't fixup reads here: they're done by
618 -- the generic optimiser below, to avoid having two separate passes
621 fixAssignsTop :: RawCmmTop -> UniqSM RawCmmTop
622 fixAssignsTop top@(CmmData _ _) = returnUs top
623 fixAssignsTop (CmmProc info lbl params blocks) =
624 mapUs fixAssignsBlock blocks `thenUs` \ blocks' ->
625 returnUs (CmmProc info lbl params blocks')
627 fixAssignsBlock :: CmmBasicBlock -> UniqSM CmmBasicBlock
628 fixAssignsBlock (BasicBlock id stmts) =
629 fixAssigns stmts `thenUs` \ stmts' ->
630 returnUs (BasicBlock id stmts')
632 fixAssigns :: [CmmStmt] -> UniqSM [CmmStmt]
634 mapUs fixAssign stmts `thenUs` \ stmtss ->
635 returnUs (concat stmtss)
637 fixAssign :: CmmStmt -> UniqSM [CmmStmt]
638 fixAssign (CmmAssign (CmmGlobal reg) src)
639 | Left realreg <- reg_or_addr
640 = returnUs [CmmAssign (CmmGlobal reg) src]
641 | Right baseRegAddr <- reg_or_addr
642 = returnUs [CmmStore baseRegAddr src]
643 -- Replace register leaves with appropriate StixTrees for
644 -- the given target. GlobalRegs which map to a reg on this
645 -- arch are left unchanged. Assigning to BaseReg is always
646 -- illegal, so we check for that.
648 reg_or_addr = get_GlobalReg_reg_or_addr reg
650 fixAssign other_stmt = returnUs [other_stmt]
652 -- -----------------------------------------------------------------------------
653 -- Generic Cmm optimiser
659 (b) Simple inlining: a temporary which is assigned to and then
660 used, once, can be shorted.
661 (c) Replacement of references to GlobalRegs which do not have
662 machine registers by the appropriate memory load (eg.
663 Hp ==> *(BaseReg + 34) ).
664 (d) Position independent code and dynamic linking
665 (i) introduce the appropriate indirections
666 and position independent refs
667 (ii) compile a list of imported symbols
669 Ideas for other things we could do (ToDo):
671 - shortcut jumps-to-jumps
672 - eliminate dead code blocks
673 - simple CSE: if an expr is assigned to a temp, then replace later occs of
674 that expr with the temp, until the expr is no longer valid (can push through
675 temp assignments, and certain assigns to mem...)
678 cmmToCmm :: DynFlags -> RawCmmTop -> (RawCmmTop, [CLabel])
679 cmmToCmm _ top@(CmmData _ _) = (top, [])
680 cmmToCmm dflags (CmmProc info lbl params blocks) = runCmmOpt dflags $ do
681 blocks' <- mapM cmmBlockConFold (cmmMiniInline blocks)
682 return $ CmmProc info lbl params blocks'
684 newtype CmmOptM a = CmmOptM (([CLabel], DynFlags) -> (# a, [CLabel] #))
686 instance Monad CmmOptM where
687 return x = CmmOptM $ \(imports, _) -> (# x,imports #)
689 CmmOptM $ \(imports, dflags) ->
690 case f (imports, dflags) of
693 CmmOptM g' -> g' (imports', dflags)
695 addImportCmmOpt :: CLabel -> CmmOptM ()
696 addImportCmmOpt lbl = CmmOptM $ \(imports, dflags) -> (# (), lbl:imports #)
698 getDynFlagsCmmOpt :: CmmOptM DynFlags
699 getDynFlagsCmmOpt = CmmOptM $ \(imports, dflags) -> (# dflags, imports #)
701 runCmmOpt :: DynFlags -> CmmOptM a -> (a, [CLabel])
702 runCmmOpt dflags (CmmOptM f) = case f ([], dflags) of
703 (# result, imports #) -> (result, imports)
705 cmmBlockConFold :: CmmBasicBlock -> CmmOptM CmmBasicBlock
706 cmmBlockConFold (BasicBlock id stmts) = do
707 stmts' <- mapM cmmStmtConFold stmts
708 return $ BasicBlock id stmts'
713 -> do src' <- cmmExprConFold DataReference src
714 return $ case src' of
715 CmmReg reg' | reg == reg' -> CmmNop
716 new_src -> CmmAssign reg new_src
719 -> do addr' <- cmmExprConFold DataReference addr
720 src' <- cmmExprConFold DataReference src
721 return $ CmmStore addr' src'
724 -> do addr' <- cmmExprConFold JumpReference addr
725 return $ CmmJump addr' regs
727 CmmCall target regs args srt returns
728 -> do target' <- case target of
729 CmmCallee e conv -> do
730 e' <- cmmExprConFold CallReference e
731 return $ CmmCallee e' conv
732 other -> return other
733 args' <- mapM (\(arg, hint) -> do
734 arg' <- cmmExprConFold DataReference arg
735 return (arg', hint)) args
736 return $ CmmCall target' regs args' srt returns
738 CmmCondBranch test dest
739 -> do test' <- cmmExprConFold DataReference test
740 return $ case test' of
741 CmmLit (CmmInt 0 _) ->
742 CmmComment (mkFastString ("deleted: " ++
743 showSDoc (pprStmt stmt)))
745 CmmLit (CmmInt n _) -> CmmBranch dest
746 other -> CmmCondBranch test' dest
749 -> do expr' <- cmmExprConFold DataReference expr
750 return $ CmmSwitch expr' ids
756 cmmExprConFold referenceKind expr
759 -> do addr' <- cmmExprConFold DataReference addr
760 return $ CmmLoad addr' rep
763 -- For MachOps, we first optimize the children, and then we try
764 -- our hand at some constant-folding.
765 -> do args' <- mapM (cmmExprConFold DataReference) args
766 return $ cmmMachOpFold mop args'
768 CmmLit (CmmLabel lbl)
770 dflags <- getDynFlagsCmmOpt
771 cmmMakeDynamicReference dflags addImportCmmOpt referenceKind lbl
772 CmmLit (CmmLabelOff lbl off)
774 dflags <- getDynFlagsCmmOpt
775 dynRef <- cmmMakeDynamicReference dflags addImportCmmOpt referenceKind lbl
776 return $ cmmMachOpFold (MO_Add wordRep) [
778 (CmmLit $ CmmInt (fromIntegral off) wordRep)
781 #if powerpc_TARGET_ARCH
782 -- On powerpc (non-PIC), it's easier to jump directly to a label than
783 -- to use the register table, so we replace these registers
784 -- with the corresponding labels:
785 CmmReg (CmmGlobal GCEnter1)
787 -> cmmExprConFold referenceKind $
788 CmmLit (CmmLabel (mkRtsCodeLabel SLIT( "__stg_gc_enter_1")))
789 CmmReg (CmmGlobal GCFun)
791 -> cmmExprConFold referenceKind $
792 CmmLit (CmmLabel (mkRtsCodeLabel SLIT( "__stg_gc_fun")))
795 CmmReg (CmmGlobal mid)
796 -- Replace register leaves with appropriate StixTrees for
797 -- the given target. MagicIds which map to a reg on this
798 -- arch are left unchanged. For the rest, BaseReg is taken
799 -- to mean the address of the reg table in MainCapability,
800 -- and for all others we generate an indirection to its
801 -- location in the register table.
802 -> case get_GlobalReg_reg_or_addr mid of
803 Left realreg -> return expr
806 BaseReg -> cmmExprConFold DataReference baseRegAddr
807 other -> cmmExprConFold DataReference
808 (CmmLoad baseRegAddr (globalRegRep mid))
809 -- eliminate zero offsets
811 -> cmmExprConFold referenceKind (CmmReg reg)
813 CmmRegOff (CmmGlobal mid) offset
814 -- RegOf leaves are just a shorthand form. If the reg maps
815 -- to a real reg, we keep the shorthand, otherwise, we just
816 -- expand it and defer to the above code.
817 -> case get_GlobalReg_reg_or_addr mid of
818 Left realreg -> return expr
820 -> cmmExprConFold DataReference (CmmMachOp (MO_Add wordRep) [
821 CmmReg (CmmGlobal mid),
822 CmmLit (CmmInt (fromIntegral offset)
827 -- -----------------------------------------------------------------------------