1 ----------------------------------------------------------------------------
3 -- Pretty-printing of Cmm as (a superset of) C--
5 -- (c) The University of Glasgow 2004-2006
7 -----------------------------------------------------------------------------
10 -- This is where we walk over Cmm emitting an external representation,
11 -- suitable for parsing, in a syntax strongly reminiscent of C--. This
12 -- is the "External Core" for the Cmm layer.
14 -- As such, this should be a well-defined syntax: we want it to look nice.
15 -- Thus, we try wherever possible to use syntax defined in [1],
16 -- "The C-- Reference Manual", http://www.cminusminus.org/. We differ
17 -- slightly, in some cases. For one, we use I8 .. I64 for types, rather
18 -- than C--'s bits8 .. bits64.
20 -- We try to ensure that all information available in the abstract
21 -- syntax is reproduced, or reproducible, in the concrete syntax.
22 -- Data that is not in printed out can be reconstructed according to
23 -- conventions used in the pretty printer. There are at least two such
25 -- 1) if a value has wordRep type, the type is not appended in the
27 -- 2) MachOps that operate over wordRep type are printed in a
28 -- C-style, rather than as their internal MachRep name.
30 -- These conventions produce much more readable Cmm output.
32 -- A useful example pass over Cmm is in nativeGen/MachCodeGen.hs
36 writeCmms, pprCmms, pprCmm, pprStmt, pprExpr
39 #include "HsVersions.h"
55 pprCmms :: [Cmm] -> SDoc
56 pprCmms cmms = pprCode CStyle (vcat (intersperse separator $ map ppr cmms))
58 separator = space $$ ptext SLIT("-------------------") $$ space
60 writeCmms :: Handle -> [Cmm] -> IO ()
61 writeCmms handle cmms = printForC handle (pprCmms cmms)
63 -----------------------------------------------------------------------------
65 instance Outputable Cmm where
68 instance Outputable CmmTop where
71 instance Outputable CmmBasicBlock where
74 instance Outputable CmmStmt where
77 instance Outputable CmmExpr where
80 instance Outputable CmmReg where
83 instance Outputable GlobalReg where
84 ppr e = pprGlobalReg e
86 -----------------------------------------------------------------------------
89 pprCmm (Cmm tops) = vcat $ intersperse (text "") $ map pprTop tops
91 -- --------------------------------------------------------------------------
92 -- Top level `procedure' blocks. The info tables, if not null, are
93 -- printed in the style of C--'s 'stackdata' declaration, just inside
94 -- the proc body, and are labelled with the procedure name ++ "_info".
96 pprTop :: CmmTop -> SDoc
97 pprTop (CmmProc info lbl params blocks )
99 = vcat [ pprCLabel lbl <> parens (commafy $ map pprLocalReg params) <+> lbrace
100 , nest 8 $ pprInfo info lbl
101 , nest 4 $ vcat (map ppr blocks)
107 (hang (pprCLabel (entryLblToInfoLbl label) <+> lbrace )
108 4 $ vcat (map pprStatic i))
111 -- --------------------------------------------------------------------------
112 -- We follow [1], 4.5
114 -- section "data" { ... }
116 pprTop (CmmData section ds) =
117 (hang (pprSection section <+> lbrace) 4 (vcat (map pprStatic ds)))
121 -- --------------------------------------------------------------------------
122 -- Basic blocks look like assembly blocks.
123 -- lbl: stmt ; stmt ; ..
124 pprBBlock :: CmmBasicBlock -> SDoc
125 pprBBlock (BasicBlock ident stmts) =
126 hang (pprBlockId ident <> colon) 4 (vcat (map ppr stmts))
128 -- --------------------------------------------------------------------------
129 -- Statements. C-- usually, exceptions to this should be obvious.
131 pprStmt :: CmmStmt -> SDoc
132 pprStmt stmt = case stmt of
138 CmmComment s -> text "//" <+> ftext s
141 CmmAssign reg expr -> ppr reg <+> equals <+> ppr expr <> semi
144 CmmStore lv expr -> rep <> brackets(ppr lv) <+> equals <+> ppr expr <> semi
146 rep = ppr ( cmmExprRep expr )
148 -- call "ccall" foo(x, y)[r1, r2];
150 CmmCall (CmmForeignCall fn cconv) results args _volatile ->
151 hcat [ ptext SLIT("call"), space,
152 doubleQuotes(ppr cconv), space,
153 target fn, parens ( commafy $ map ppr args ),
156 else brackets( commafy $ map ppr results)), semi ]
158 target (CmmLit lit) = pprLit lit
159 target fn' = parens (ppr fn')
161 CmmCall (CmmPrim op) results args volatile ->
162 pprStmt (CmmCall (CmmForeignCall (CmmLit lbl) CCallConv)
163 results args volatile)
165 lbl = CmmLabel (mkForeignLabel (mkFastString (show op)) Nothing False)
167 CmmBranch ident -> genBranch ident
168 CmmCondBranch expr ident -> genCondBranch expr ident
169 CmmJump expr params -> genJump expr params
170 CmmReturn params -> genReturn params
171 CmmSwitch arg ids -> genSwitch arg ids
173 -- --------------------------------------------------------------------------
174 -- goto local label. [1], section 6.6
178 genBranch :: BlockId -> SDoc
180 ptext SLIT("goto") <+> pprBlockId ident <> semi
182 -- --------------------------------------------------------------------------
183 -- Conditional. [1], section 6.4
185 -- if (expr) { goto lbl; }
187 genCondBranch :: CmmExpr -> BlockId -> SDoc
188 genCondBranch expr ident =
189 hsep [ ptext SLIT("if")
192 , pprBlockId ident <> semi ]
194 -- --------------------------------------------------------------------------
195 -- A tail call. [1], Section 6.9
197 -- jump foo(a, b, c);
199 genJump :: CmmExpr -> [(CmmExpr, MachHint)] -> SDoc
202 hcat [ ptext SLIT("jump")
204 , if isTrivialCmmExpr expr
207 CmmLoad (CmmReg _) _ -> pprExpr expr
208 _ -> parens (pprExpr expr)
210 , parens ( commafy $ map ppr args )
213 -- --------------------------------------------------------------------------
214 -- Return from a function. [1], Section 6.8.2 of version 1.128
218 genReturn :: [(CmmExpr, MachHint)] -> SDoc
221 hcat [ ptext SLIT("return")
223 , parens ( commafy $ map ppr args )
226 -- --------------------------------------------------------------------------
227 -- Tabled jump to local label
229 -- The syntax is from [1], section 6.5
231 -- switch [0 .. n] (expr) { case ... ; }
233 genSwitch :: CmmExpr -> [Maybe BlockId] -> SDoc
234 genSwitch expr maybe_ids
236 = let pairs = groupBy snds (zip [0 .. ] maybe_ids )
238 in hang (hcat [ ptext SLIT("switch [0 .. ")
239 , int (length maybe_ids - 1)
241 , if isTrivialCmmExpr expr
243 else parens (pprExpr expr)
246 4 (vcat ( map caseify pairs )) $$ rbrace
249 snds a b = (snd a) == (snd b)
251 caseify :: [(Int,Maybe BlockId)] -> SDoc
252 caseify ixs@((i,Nothing):_)
253 = ptext SLIT("/* impossible: ") <> hcat (intersperse comma (map (int.fst) ixs))
256 = let (is,ids) = unzip as
257 in hsep [ ptext SLIT("case")
258 , hcat (punctuate comma (map int is))
259 , ptext SLIT(": goto")
260 , pprBlockId (head [ id | Just id <- ids]) <> semi ]
262 -- --------------------------------------------------------------------------
266 pprExpr :: CmmExpr -> SDoc
270 pprExpr (CmmMachOp (MO_Add rep)
271 [CmmReg reg, CmmLit (CmmInt (fromIntegral i) rep)])
272 where rep = cmmRegRep reg
273 CmmLit lit -> pprLit lit
276 -- Here's the precedence table from CmmParse.y:
277 -- %nonassoc '>=' '>' '<=' '<' '!=' '=='
286 -- We just cope with the common operators for now, the rest will get
287 -- a default conservative behaviour.
289 -- %nonassoc '>=' '>' '<=' '<' '!=' '=='
290 pprExpr1 (CmmMachOp op [x,y]) | Just doc <- infixMachOp1 op
291 = pprExpr7 x <+> doc <+> pprExpr7 y
292 pprExpr1 e = pprExpr7 e
294 infixMachOp1 (MO_Eq _) = Just (ptext SLIT("=="))
295 infixMachOp1 (MO_Ne _) = Just (ptext SLIT("!="))
296 infixMachOp1 (MO_Shl _) = Just (ptext SLIT("<<"))
297 infixMachOp1 (MO_U_Shr _) = Just (ptext SLIT(">>"))
298 infixMachOp1 (MO_U_Ge _) = Just (ptext SLIT(">="))
299 infixMachOp1 (MO_U_Le _) = Just (ptext SLIT("<="))
300 infixMachOp1 (MO_U_Gt _) = Just (char '>')
301 infixMachOp1 (MO_U_Lt _) = Just (char '<')
302 infixMachOp1 _ = Nothing
305 pprExpr7 (CmmMachOp (MO_Add rep1) [x, CmmLit (CmmInt i rep2)]) | i < 0
306 = pprExpr7 (CmmMachOp (MO_Sub rep1) [x, CmmLit (CmmInt (negate i) rep2)])
307 pprExpr7 (CmmMachOp op [x,y]) | Just doc <- infixMachOp7 op
308 = pprExpr7 x <+> doc <+> pprExpr8 y
309 pprExpr7 e = pprExpr8 e
311 infixMachOp7 (MO_Add _) = Just (char '+')
312 infixMachOp7 (MO_Sub _) = Just (char '-')
313 infixMachOp7 _ = Nothing
316 pprExpr8 (CmmMachOp op [x,y]) | Just doc <- infixMachOp8 op
317 = pprExpr8 x <+> doc <+> pprExpr9 y
318 pprExpr8 e = pprExpr9 e
320 infixMachOp8 (MO_U_Quot _) = Just (char '/')
321 infixMachOp8 (MO_Mul _) = Just (char '*')
322 infixMachOp8 (MO_U_Rem _) = Just (char '%')
323 infixMachOp8 _ = Nothing
325 pprExpr9 :: CmmExpr -> SDoc
328 CmmLit lit -> pprLit1 lit
329 CmmLoad expr rep -> ppr rep <> brackets( ppr expr )
330 CmmReg reg -> ppr reg
331 CmmRegOff reg off -> parens (ppr reg <+> char '+' <+> int off)
332 CmmMachOp mop args -> genMachOp mop args
334 genMachOp :: MachOp -> [CmmExpr] -> SDoc
336 | Just doc <- infixMachOp mop = case args of
338 [x,y] -> pprExpr9 x <+> doc <+> pprExpr9 y
341 [x] -> doc <> pprExpr9 x
343 _ -> pprTrace "PprCmm.genMachOp: machop with strange number of args"
345 parens (hcat $ punctuate comma (map pprExpr args)))
348 | isJust (infixMachOp1 mop)
349 || isJust (infixMachOp7 mop)
350 || isJust (infixMachOp8 mop) = parens (pprExpr (CmmMachOp mop args))
352 | otherwise = char '%' <> ppr_op <> parens (commafy (map pprExpr args))
353 where ppr_op = text (map (\c -> if c == ' ' then '_' else c)
355 -- replace spaces in (show mop) with underscores,
358 -- Unsigned ops on the word size of the machine get nice symbols.
359 -- All else get dumped in their ugly format.
361 infixMachOp :: MachOp -> Maybe SDoc
364 MO_And _ -> Just $ char '&'
365 MO_Or _ -> Just $ char '|'
366 MO_Xor _ -> Just $ char '^'
367 MO_Not _ -> Just $ char '~'
368 MO_S_Neg _ -> Just $ char '-' -- there is no unsigned neg :)
371 -- --------------------------------------------------------------------------
373 -- To minimise line noise we adopt the convention that if the literal
374 -- has the natural machine word size, we do not append the type
376 pprLit :: CmmLit -> SDoc
377 pprLit lit = case lit of
379 hcat [ (if i < 0 then parens else id)(integer i)
382 else space <> dcolon <+> ppr rep) ]
384 CmmFloat f rep -> hsep [ rational f, dcolon, ppr rep ]
385 CmmLabel clbl -> pprCLabel clbl
386 CmmLabelOff clbl i -> pprCLabel clbl <> ppr_offset i
387 CmmLabelDiffOff clbl1 clbl2 i -> pprCLabel clbl1 <> char '-'
388 <> pprCLabel clbl2 <> ppr_offset i
390 pprLit1 lit@(CmmLabelOff clbl i) = parens (pprLit lit)
391 pprLit1 lit = pprLit lit
393 ppr_offset :: Int -> SDoc
396 | i>=0 = char '+' <> int i
397 | otherwise = char '-' <> int (-i)
399 -- --------------------------------------------------------------------------
401 -- Strings are printed as C strings, and we print them as I8[],
404 pprStatic :: CmmStatic -> SDoc
405 pprStatic s = case s of
406 CmmStaticLit lit -> nest 4 $ ptext SLIT("const") <+> pprLit lit <> semi
407 CmmUninitialised i -> nest 4 $ text "I8" <> brackets (int i)
408 CmmAlign i -> nest 4 $ text "align" <+> int i
409 CmmDataLabel clbl -> pprCLabel clbl <> colon
410 CmmString s' -> nest 4 $ text "I8[]" <+> text (show s')
412 -- --------------------------------------------------------------------------
413 -- Registers, whether local (temps) or global
415 pprReg :: CmmReg -> SDoc
418 CmmLocal local -> pprLocalReg local
419 CmmGlobal global -> pprGlobalReg global
422 -- We only print the type of the local reg if it isn't wordRep
424 pprLocalReg :: LocalReg -> SDoc
425 pprLocalReg (LocalReg uniq rep)
426 = hcat [ char '_', ppr uniq,
428 then empty else dcolon <> ppr rep) ]
430 -- needs to be kept in syn with Cmm.hs.GlobalReg
432 pprGlobalReg :: GlobalReg -> SDoc
435 VanillaReg n -> char 'R' <> int n
436 FloatReg n -> char 'F' <> int n
437 DoubleReg n -> char 'D' <> int n
438 LongReg n -> char 'L' <> int n
439 Sp -> ptext SLIT("Sp")
440 SpLim -> ptext SLIT("SpLim")
441 Hp -> ptext SLIT("Hp")
442 HpLim -> ptext SLIT("HpLim")
443 CurrentTSO -> ptext SLIT("CurrentTSO")
444 CurrentNursery -> ptext SLIT("CurrentNursery")
445 HpAlloc -> ptext SLIT("HpAlloc")
446 GCEnter1 -> ptext SLIT("stg_gc_enter_1")
447 GCFun -> ptext SLIT("stg_gc_fun")
448 BaseReg -> ptext SLIT("BaseReg")
449 PicBaseReg -> ptext SLIT("PicBaseReg")
451 -- --------------------------------------------------------------------------
454 pprSection :: Section -> SDoc
455 pprSection s = case s of
456 Text -> section <+> doubleQuotes (ptext SLIT("text"))
457 Data -> section <+> doubleQuotes (ptext SLIT("data"))
458 ReadOnlyData -> section <+> doubleQuotes (ptext SLIT("readonly"))
459 RelocatableReadOnlyData
460 -> section <+> doubleQuotes (ptext SLIT("relreadonly"))
461 UninitialisedData -> section <+> doubleQuotes (ptext SLIT("uninitialised"))
462 OtherSection s' -> section <+> doubleQuotes (text s')
464 section = ptext SLIT("section")
466 -- --------------------------------------------------------------------------
469 pprBlockId :: BlockId -> SDoc
470 pprBlockId b = ppr $ getUnique b
472 -----------------------------------------------------------------------------
474 commafy :: [SDoc] -> SDoc
475 commafy xs = hsep $ punctuate comma xs