1 module PositionIndependentCode (
2 cmmMakeDynamicReference,
11 This module handles generation of position independent code and
12 dynamic-linking related issues for the native code generator.
14 Things outside this module which are related to this:
17 - PIC base label (pretty printed as local label 1)
18 - DynamicLinkerLabels - several kinds:
19 CodeStub, SymbolPtr, GotSymbolPtr, GotSymbolOffset
20 - labelDynamic predicate
22 - The GlobalReg datatype has a PicBaseReg constructor
23 - The CmmLit datatype has a CmmLabelDiffOff constructor
25 - When tablesNextToCode, no absolute addresses are stored in info tables
26 any more. Instead, offsets from the info label are used.
27 - For Win32 only, SRTs might contain addresses of __imp_ symbol pointers
28 because Win32 doesn't support external references in data sections.
29 TODO: make sure this still works, it might be bitrotted
31 - The cmmToCmm pass in AsmCodeGen calls cmmMakeDynamicReference for all
33 - nativeCodeGen calls pprImportedSymbol and pprGotDeclaration to output
34 all the necessary stuff for imported symbols.
35 - The NCG monad keeps track of a list of imported symbols.
36 - MachCodeGen invokes initializePicBase to generate code to initialize
37 the PIC base register when needed.
38 - MachCodeGen calls cmmMakeDynamicReference whenever it uses a CLabel
39 that wasn't in the original Cmm code (e.g. floating point literals).
41 - The mangler converts absolure refs to relative refs in info tables
42 - Symbol pointers, stub code and PIC calculations that are generated
43 by GCC are left intact by the mangler (so far only on ppc-darwin
47 #include "HsVersions.h"
48 #include "nativeGen/NCG.h"
51 import MachOp ( MachOp(MO_Add), wordRep, MachRep(..) )
52 import CLabel ( CLabel, pprCLabel,
53 mkDynamicLinkerLabel, DynamicLinkerLabelInfo(..),
54 dynamicLinkerLabelInfo, mkPicBaseLabel,
55 labelDynamic, externallyVisibleCLabel )
58 import CLabel ( mkForeignLabel )
63 import NCGMonad ( NatM, getNewRegNat, getNewLabelNat )
65 import StaticFlags ( opt_PIC, opt_Static )
68 import qualified Outputable
70 import Panic ( panic )
74 -- The most important function here is cmmMakeDynamicReference.
76 -- It gets called by the cmmToCmm pass for every CmmLabel in the Cmm
77 -- code. It does The Right Thing(tm) to convert the CmmLabel into a
78 -- position-independent, dynamic-linking-aware reference to the thing
80 -- Note that this also has to be called from MachCodeGen in order to
81 -- access static data like floating point literals (labels that were
82 -- created after the cmmToCmm pass).
83 -- The function must run in a monad that can keep track of imported symbols
84 -- A function for recording an imported symbol must be passed in:
85 -- - addImportCmmOpt for the CmmOptM monad
86 -- - addImportNat for the NatM monad.
88 data ReferenceKind = DataReference
93 cmmMakeDynamicReference
94 :: Monad m => DynFlags
95 -> (CLabel -> m ()) -- a monad & a function
96 -- used for recording imported symbols
97 -> ReferenceKind -- whether this is the target of a jump
98 -> CLabel -- the label
101 cmmMakeDynamicReference dflags addImport referenceKind lbl
102 | Just _ <- dynamicLinkerLabelInfo lbl
103 = return $ CmmLit $ CmmLabel lbl -- already processed it, pass through
104 | otherwise = case howToAccessLabel dflags referenceKind lbl of
106 let stub = mkDynamicLinkerLabel CodeStub lbl
108 return $ CmmLit $ CmmLabel stub
109 AccessViaSymbolPtr -> do
110 let symbolPtr = mkDynamicLinkerLabel SymbolPtr lbl
112 return $ CmmLoad (cmmMakePicReference symbolPtr) wordRep
113 AccessDirectly -> case referenceKind of
114 -- for data, we might have to make some calculations:
115 DataReference -> return $ cmmMakePicReference lbl
116 -- all currently supported processors support
117 -- PC-relative branch and call instructions,
118 -- so just jump there if it's a call or a jump
119 _ -> return $ CmmLit $ CmmLabel lbl
121 -- -------------------------------------------------------------------
123 -- Create a position independent reference to a label.
124 -- (but do not bother with dynamic linking).
125 -- We calculate the label's address by adding some (platform-dependent)
126 -- offset to our base register; this offset is calculated by
127 -- the function picRelative in the platform-dependent part below.
129 cmmMakePicReference :: CLabel -> CmmExpr
131 #if !mingw32_TARGET_OS
132 -- Windows doesn't need PIC,
133 -- everything gets relocated at runtime
135 cmmMakePicReference lbl
136 | (opt_PIC || not opt_Static) && absoluteLabel lbl = CmmMachOp (MO_Add wordRep) [
137 CmmReg (CmmGlobal PicBaseReg),
138 CmmLit $ picRelative lbl
141 absoluteLabel lbl = case dynamicLinkerLabelInfo lbl of
142 Just (GotSymbolPtr, _) -> False
143 Just (GotSymbolOffset, _) -> False
147 cmmMakePicReference lbl = CmmLit $ CmmLabel lbl
149 -- ===================================================================
150 -- Platform dependent stuff
151 -- ===================================================================
153 -- Knowledge about how special dynamic linker labels like symbol
154 -- pointers, code stubs and GOT offsets look like is located in the
157 -- -------------------------------------------------------------------
159 -- We have to decide which labels need to be accessed
160 -- indirectly or via a piece of stub code.
162 data LabelAccessStyle = AccessViaStub
166 howToAccessLabel :: DynFlags -> ReferenceKind -> CLabel -> LabelAccessStyle
168 #if mingw32_TARGET_OS
171 -- We need to use access *exactly* those things that
172 -- are imported from a DLL via an __imp_* label.
173 -- There are no stubs for imported code.
175 howToAccessLabel dflags _ lbl | labelDynamic (thisPackage dflags) lbl = AccessViaSymbolPtr
176 | otherwise = AccessDirectly
177 #elif darwin_TARGET_OS
178 -- Mach-O (Darwin, Mac OS X)
180 -- Indirect access is required in the following cases:
181 -- * things imported from a dynamic library
182 -- * (not on x86_64) data from a different module, if we're generating PIC code
183 -- It is always possible to access something indirectly,
184 -- even when it's not necessary.
186 howToAccessLabel dflags DataReference lbl
187 -- data access to a dynamic library goes via a symbol pointer
188 | labelDynamic (thisPackage dflags) lbl = AccessViaSymbolPtr
190 #if !x86_64_TARGET_ARCH
191 -- when generating PIC code, all cross-module data references must
192 -- must go via a symbol pointer, too, because the assembler
193 -- cannot generate code for a label difference where one
194 -- label is undefined. Doesn't apply t x86_64.
195 -- Unfortunately, we don't know whether it's cross-module,
196 -- so we do it for all externally visible labels.
197 -- This is a slight waste of time and space, but otherwise
198 -- we'd need to pass the current Module all the way in to
200 | opt_PIC && externallyVisibleCLabel lbl = AccessViaSymbolPtr
202 | otherwise = AccessDirectly
205 #if i386_TARGET_ARCH || x86_64_TARGET_ARCH
206 -- dyld code stubs don't work for tailcalls because the
207 -- stack alignment is only right for regular calls.
208 -- Therefore, we have to go via a symbol pointer:
209 howToAccessLabel dflags JumpReference lbl
210 | labelDynamic (thisPackage dflags) lbl
214 howToAccessLabel dflags _ lbl
215 #if !x86_64_TARGET_ARCH
216 -- Code stubs are the usual method of choice for imported code;
217 -- not needed on x86_64 because Apple's new linker, ld64, generates
218 -- them automatically.
219 | labelDynamic (thisPackage dflags) lbl
226 #elif linux_TARGET_OS && powerpc64_TARGET_ARCH
227 -- ELF PPC64 (powerpc64-linux), AIX, MacOS 9, BeOS/PPC
229 howToAccessLabel _ DataReference lbl = AccessViaSymbolPtr
230 howToAccessLabel _ _ lbl = AccessDirectly -- actually, .label instead of label
232 #elif linux_TARGET_OS
235 -- ELF tries to pretend to the main application code that dynamic linking does
236 -- not exist. While this may sound convenient, it tends to mess things up in
237 -- very bad ways, so we have to be careful when we generate code for the main
238 -- program (-dynamic but no -fPIC).
240 -- Indirect access is required for references to imported symbols
241 -- from position independent code. It is also required from the main program
242 -- when dynamic libraries containing Haskell code are used.
244 howToAccessLabel _ _ lbl
245 -- no PIC -> the dynamic linker does everything for us;
246 -- if we don't dynamically link to Haskell code,
247 -- it actually manages to do so without messing thins up.
248 | not opt_PIC && opt_Static = AccessDirectly
250 howToAccessLabel dflags DataReference lbl
251 -- A dynamic label needs to be accessed via a symbol pointer.
252 | labelDynamic (thisPackage dflags) lbl = AccessViaSymbolPtr
253 #if powerpc_TARGET_ARCH
254 -- For PowerPC32 -fPIC, we have to access even static data
255 -- via a symbol pointer (see below for an explanation why
256 -- PowerPC32 Linux is especially broken).
257 | opt_PIC = AccessViaSymbolPtr
259 | otherwise = AccessDirectly
262 -- In most cases, we have to avoid symbol stubs on ELF, for the following reasons:
263 -- * on i386, the position-independent symbol stubs in the Procedure Linkage Table
264 -- require the address of the GOT to be loaded into register %ebx on entry.
265 -- * The linker will take any reference to the symbol stub as a hint that
266 -- the label in question is a code label. When linking executables, this
267 -- will cause the linker to replace even data references to the label with
268 -- references to the symbol stub.
270 -- This leaves calling a (foreign) function from non-PIC code
271 -- (AccessDirectly, because we get an implicit symbol stub)
272 -- and calling functions from PIC code on non-i386 platforms (via a symbol stub)
274 howToAccessLabel dflags CallReference lbl
275 | labelDynamic (thisPackage dflags) lbl && not opt_PIC
277 #if !i386_TARGET_ARCH
278 | labelDynamic (thisPackage dflags) lbl && opt_PIC
282 howToAccessLabel dflags _ lbl
283 | labelDynamic (thisPackage dflags) lbl = AccessViaSymbolPtr
284 | otherwise = AccessDirectly
287 -- all other platforms
289 howToAccessLabel _ _ _
290 | not opt_PIC = AccessDirectly
291 | otherwise = panic "howToAccessLabel: PIC not defined for this platform"
294 -- -------------------------------------------------------------------
296 -- What do we have to add to our 'PIC base register' in order to
297 -- get the address of a label?
299 picRelative :: CLabel -> CmmLit
300 #if darwin_TARGET_OS && !x86_64_TARGET_ARCH
301 -- Darwin, but not x86_64:
302 -- The PIC base register points to the PIC base label at the beginning
303 -- of the current CmmTop. We just have to use a label difference to
305 -- We have already made sure that all labels that are not from the current
306 -- module are accessed indirectly ('as' can't calculate differences between
307 -- undefined labels).
310 = CmmLabelDiffOff lbl mkPicBaseLabel 0
312 #elif powerpc_TARGET_ARCH && linux_TARGET_OS
314 -- The PIC base register points to our fake GOT. Use a label difference
315 -- to get the offset.
316 -- We have made sure that *everything* is accessed indirectly, so this
317 -- is only used for offsets from the GOT to symbol pointers inside the
320 = CmmLabelDiffOff lbl gotLabel 0
322 #elif linux_TARGET_OS || (darwin_TARGET_OS && x86_64_TARGET_ARCH)
323 -- Most Linux versions:
324 -- The PIC base register points to the GOT. Use foo@got for symbol
325 -- pointers, and foo@gotoff for everything else.
326 -- Linux and Darwin on x86_64:
327 -- The PIC base register is %rip, we use foo@gotpcrel for symbol pointers,
328 -- and a GotSymbolOffset label for other things.
329 -- For reasons of tradition, the symbol offset label is written as a plain label.
332 | Just (SymbolPtr, lbl') <- dynamicLinkerLabelInfo lbl
333 = CmmLabel $ mkDynamicLinkerLabel GotSymbolPtr lbl'
335 = CmmLabel $ mkDynamicLinkerLabel GotSymbolOffset lbl
338 picRelative lbl = panic "PositionIndependentCode.picRelative"
341 -- -------------------------------------------------------------------
343 -- What do we have to add to every assembly file we generate?
345 -- utility function for pretty-printing asm-labels,
346 -- copied from PprMach
347 asmSDoc d = Outputable.withPprStyleDoc (
348 Outputable.mkCodeStyle Outputable.AsmStyle) d
349 pprCLabel_asm l = asmSDoc (pprCLabel l)
352 #if darwin_TARGET_OS && !x86_64_TARGET_ARCH
354 needImportedSymbols = True
356 -- We don't need to declare any offset tables.
357 -- However, for PIC on x86, we need a small helper function.
362 ptext SLIT(".section __TEXT,__textcoal_nt,coalesced,no_toc"),
363 ptext SLIT(".weak_definition ___i686.get_pc_thunk.ax"),
364 ptext SLIT(".private_extern ___i686.get_pc_thunk.ax"),
365 ptext SLIT("___i686.get_pc_thunk.ax:"),
366 ptext SLIT("\tmovl (%esp), %eax"),
369 | otherwise = Pretty.empty
371 pprGotDeclaration = Pretty.empty
374 -- On Darwin, we have to generate our own stub code for lazy binding..
375 -- For each processor architecture, there are two versions, one for PIC
376 -- and one for non-PIC.
378 -- Whenever you change something in this assembler output, make sure
379 -- the splitter in driver/split/ghc-split.lprl recognizes the new output
380 pprImportedSymbol importedLbl
381 #if powerpc_TARGET_ARCH
382 | Just (CodeStub, lbl) <- dynamicLinkerLabelInfo importedLbl
386 ptext SLIT(".symbol_stub"),
387 ptext SLIT("L") <> pprCLabel_asm lbl <> ptext SLIT("$stub:"),
388 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
389 ptext SLIT("\tlis r11,ha16(L") <> pprCLabel_asm lbl
390 <> ptext SLIT("$lazy_ptr)"),
391 ptext SLIT("\tlwz r12,lo16(L") <> pprCLabel_asm lbl
392 <> ptext SLIT("$lazy_ptr)(r11)"),
393 ptext SLIT("\tmtctr r12"),
394 ptext SLIT("\taddi r11,r11,lo16(L") <> pprCLabel_asm lbl
395 <> ptext SLIT("$lazy_ptr)"),
400 ptext SLIT(".section __TEXT,__picsymbolstub1,")
401 <> ptext SLIT("symbol_stubs,pure_instructions,32"),
402 ptext SLIT("\t.align 2"),
403 ptext SLIT("L") <> pprCLabel_asm lbl <> ptext SLIT("$stub:"),
404 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
405 ptext SLIT("\tmflr r0"),
406 ptext SLIT("\tbcl 20,31,L0$") <> pprCLabel_asm lbl,
407 ptext SLIT("L0$") <> pprCLabel_asm lbl <> char ':',
408 ptext SLIT("\tmflr r11"),
409 ptext SLIT("\taddis r11,r11,ha16(L") <> pprCLabel_asm lbl
410 <> ptext SLIT("$lazy_ptr-L0$") <> pprCLabel_asm lbl <> char ')',
411 ptext SLIT("\tmtlr r0"),
412 ptext SLIT("\tlwzu r12,lo16(L") <> pprCLabel_asm lbl
413 <> ptext SLIT("$lazy_ptr-L0$") <> pprCLabel_asm lbl
414 <> ptext SLIT(")(r11)"),
415 ptext SLIT("\tmtctr r12"),
419 ptext SLIT(".lazy_symbol_pointer"),
420 ptext SLIT("L") <> pprCLabel_asm lbl <> ptext SLIT("$lazy_ptr:"),
421 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
422 ptext SLIT("\t.long dyld_stub_binding_helper")
424 #elif i386_TARGET_ARCH
425 | Just (CodeStub, lbl) <- dynamicLinkerLabelInfo importedLbl
429 ptext SLIT(".symbol_stub"),
430 ptext SLIT("L") <> pprCLabel_asm lbl <> ptext SLIT("$stub:"),
431 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
432 ptext SLIT("\tjmp *L") <> pprCLabel_asm lbl
433 <> ptext SLIT("$lazy_ptr"),
434 ptext SLIT("L") <> pprCLabel_asm lbl
435 <> ptext SLIT("$stub_binder:"),
436 ptext SLIT("\tpushl $L") <> pprCLabel_asm lbl
437 <> ptext SLIT("$lazy_ptr"),
438 ptext SLIT("\tjmp dyld_stub_binding_helper")
442 ptext SLIT(".section __TEXT,__picsymbolstub2,")
443 <> ptext SLIT("symbol_stubs,pure_instructions,25"),
444 ptext SLIT("L") <> pprCLabel_asm lbl <> ptext SLIT("$stub:"),
445 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
446 ptext SLIT("\tcall ___i686.get_pc_thunk.ax"),
448 ptext SLIT("\tmovl L") <> pprCLabel_asm lbl
449 <> ptext SLIT("$lazy_ptr-1b(%eax),%edx"),
450 ptext SLIT("\tjmp *%edx"),
451 ptext SLIT("L") <> pprCLabel_asm lbl
452 <> ptext SLIT("$stub_binder:"),
453 ptext SLIT("\tlea L") <> pprCLabel_asm lbl
454 <> ptext SLIT("$lazy_ptr-1b(%eax),%eax"),
455 ptext SLIT("\tpushl %eax"),
456 ptext SLIT("\tjmp dyld_stub_binding_helper")
458 $+$ vcat [ ptext SLIT(".section __DATA, __la_sym_ptr")
459 <> (if opt_PIC then int 2 else int 3)
460 <> ptext SLIT(",lazy_symbol_pointers"),
461 ptext SLIT("L") <> pprCLabel_asm lbl <> ptext SLIT("$lazy_ptr:"),
462 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
463 ptext SLIT("\t.long L") <> pprCLabel_asm lbl
464 <> ptext SLIT("$stub_binder")
467 -- We also have to declare our symbol pointers ourselves:
468 | Just (SymbolPtr, lbl) <- dynamicLinkerLabelInfo importedLbl
470 ptext SLIT(".non_lazy_symbol_pointer"),
471 char 'L' <> pprCLabel_asm lbl <> ptext SLIT("$non_lazy_ptr:"),
472 ptext SLIT("\t.indirect_symbol") <+> pprCLabel_asm lbl,
473 ptext SLIT("\t.long\t0")
478 #elif linux_TARGET_OS && !powerpc64_TARGET_ARCH
482 -- In theory, we don't need to generate any stubs or symbol pointers
483 -- by hand for Linux.
485 -- Reality differs from this in two areas.
487 -- 1) If we just use a dynamically imported symbol directly in a read-only
488 -- section of the main executable (as GCC does), ld generates R_*_COPY
489 -- relocations, which are fundamentally incompatible with reversed info
490 -- tables. Therefore, we need a table of imported addresses in a writable
492 -- The "official" GOT mechanism (label@got) isn't intended to be used
493 -- in position dependent code, so we have to create our own "fake GOT"
494 -- when not opt_PCI && not opt_Static.
496 -- 2) PowerPC Linux is just plain broken.
497 -- While it's theoretically possible to use GOT offsets larger
498 -- than 16 bit, the standard crt*.o files don't, which leads to
499 -- linker errors as soon as the GOT size exceeds 16 bit.
500 -- Also, the assembler doesn't support @gotoff labels.
501 -- In order to be able to use a larger GOT, we have to circumvent the
502 -- entire GOT mechanism and do it ourselves (this is also what GCC does).
505 -- When needImportedSymbols is defined,
506 -- the NCG will keep track of all DynamicLinkerLabels it uses
507 -- and output each of them using pprImportedSymbol.
508 #if powerpc_TARGET_ARCH
509 -- PowerPC Linux: -fPIC or -dynamic
510 needImportedSymbols = opt_PIC || not opt_Static
512 -- i386 (and others?): -dynamic but not -fPIC
513 needImportedSymbols = not opt_Static && not opt_PIC
517 -- The label used to refer to our "fake GOT" from
518 -- position-independent code.
519 gotLabel = mkForeignLabel -- HACK: it's not really foreign
520 FSLIT(".LCTOC1") Nothing False
523 -- Output whatever needs to be output once per .s file.
524 -- The .LCTOC1 label is defined to point 32768 bytes into the table,
525 -- to make the most of the PPC's 16-bit displacements.
526 -- Only needed for PIC.
529 | not opt_PIC = Pretty.empty
531 ptext SLIT(".section \".got2\",\"aw\""),
532 ptext SLIT(".LCTOC1 = .+32768")
535 -- We generate one .long/.quad literal for every symbol we import;
536 -- the dynamic linker will relocate those addresses.
538 pprImportedSymbol importedLbl
539 | Just (SymbolPtr, lbl) <- dynamicLinkerLabelInfo importedLbl
541 ptext SLIT(".section \".got2\", \"aw\""),
542 ptext SLIT(".LC_") <> pprCLabel_asm lbl <> char ':',
543 ptext symbolSize <+> pprCLabel_asm lbl
546 -- PLT code stubs are generated automatically be the dynamic linker.
549 symbolSize = case wordRep of
550 I32 -> SLIT("\t.long")
551 I64 -> SLIT("\t.quad")
552 _ -> panic "Unknown wordRep in pprImportedSymbol"
556 -- For all other currently supported platforms, we don't need to do
559 needImportedSymbols = False
560 pprGotDeclaration = Pretty.empty
561 pprImportedSymbol _ = empty
564 -- -------------------------------------------------------------------
566 -- Generate code to calculate the address that should be put in the
567 -- PIC base register.
568 -- This is called by MachCodeGen for every CmmProc that accessed the
569 -- PIC base register. It adds the appropriate instructions to the
570 -- top of the CmmProc.
572 -- It is assumed that the first NatCmmTop in the input list is a Proc
573 -- and the rest are CmmDatas.
575 initializePicBase :: Reg -> [NatCmmTop] -> NatM [NatCmmTop]
579 -- Darwin is simple: just fetch the address of a local label.
580 -- The FETCHPC pseudo-instruction is expanded to multiple instructions
581 -- during pretty-printing so that we don't have to deal with the
592 initializePicBase picReg (CmmProc info lab params blocks : statics)
593 = return (CmmProc info lab params (b':tail blocks) : statics)
594 where BasicBlock bID insns = head blocks
595 b' = BasicBlock bID (FETCHPC picReg : insns)
597 #elif powerpc_TARGET_ARCH && linux_TARGET_OS
599 -- Get a pointer to our own fake GOT, which is defined on a per-module basis.
600 -- This is exactly how GCC does it, and it's quite horrible:
601 -- We first fetch the address of a local label (mkPicBaseLabel).
602 -- Then we add a 16-bit offset to that to get the address of a .long that we
603 -- define in .text space right next to the proc. This .long literal contains
604 -- the (32-bit) offset from our local label to our global offset table
605 -- (.LCTOC1 aka gotOffLabel).
606 initializePicBase picReg
607 (CmmProc info lab params blocks : statics)
609 gotOffLabel <- getNewLabelNat
610 tmp <- getNewRegNat wordRep
612 gotOffset = CmmData Text [
613 CmmDataLabel gotOffLabel,
614 CmmStaticLit (CmmLabelDiffOff gotLabel
618 offsetToOffset = ImmConstantDiff (ImmCLbl gotOffLabel)
619 (ImmCLbl mkPicBaseLabel)
620 BasicBlock bID insns = head blocks
621 b' = BasicBlock bID (FETCHPC picReg
623 (AddrRegImm picReg offsetToOffset)
624 : ADD picReg picReg (RIReg tmp)
626 return (CmmProc info lab params (b' : tail blocks) : gotOffset : statics)
627 #elif i386_TARGET_ARCH && linux_TARGET_OS
629 -- We cheat a bit here by defining a pseudo-instruction named FETCHGOT
630 -- which pretty-prints as:
633 -- addl __GLOBAL_OFFSET_TABLE__+.-1b, %picReg
636 initializePicBase picReg (CmmProc info lab params blocks : statics)
637 = return (CmmProc info lab params (b':tail blocks) : statics)
638 where BasicBlock bID insns = head blocks
639 b' = BasicBlock bID (FETCHGOT picReg : insns)
642 initializePicBase picReg proc = panic "initializePicBase"
644 -- mingw32_TARGET_OS: not needed, won't be called