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* Remove the old codegenSimon Marlow2012-10-191-490/+0
| | | | | Except for CgUtils.fixStgRegisters that is used in the NCG and LLVM backends, and should probably be moved somewhere else.
* Some alpha renamingIan Lynagh2012-10-161-3/+3
| | | | | Mostly d -> g (matching DynFlag -> GeneralFlag). Also renamed if* to when*, matching the Haskell if/when names
* Produce new-style Cmm from the Cmm parserSimon Marlow2012-10-081-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The main change here is that the Cmm parser now allows high-level cmm code with argument-passing and function calls. For example: foo ( gcptr a, bits32 b ) { if (b > 0) { // we can make tail calls passing arguments: jump stg_ap_0_fast(a); } return (x,y); } More details on the new cmm syntax are in Note [Syntax of .cmm files] in CmmParse.y. The old syntax is still more-or-less supported for those occasional code fragments that really need to explicitly manipulate the stack. However there are a couple of differences: it is now obligatory to give a list of live GlobalRegs on every jump, e.g. jump %ENTRY_CODE(Sp(0)) [R1]; Again, more details in Note [Syntax of .cmm files]. I have rewritten most of the .cmm files in the RTS into the new syntax, except for AutoApply.cmm which is generated by the genapply program: this file could be generated in the new syntax instead and would probably be better off for it, but I ran out of enthusiasm. Some other changes in this batch: - The PrimOp calling convention is gone, primops now use the ordinary NativeNodeCall convention. This means that primops and "foreign import prim" code must be written in high-level cmm, but they can now take more than 10 arguments. - CmmSink now does constant-folding (should fix #7219) - .cmm files now go through the cmmPipeline, and as a result we generate better code in many cases. All the object files generated for the RTS .cmm files are now smaller. Performance should be better too, but I haven't measured it yet. - RET_DYN frames are removed from the RTS, lots of code goes away - we now have some more canned GC points to cover unboxed-tuples with 2-4 pointers, which will reduce code size a little.
* Move tAG_BITS into platformConstantsIan Lynagh2012-09-161-9/+10
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* Move wORD_SIZE into platformConstantsIan Lynagh2012-09-161-4/+4
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* Move some more constants fo platformConstantsIan Lynagh2012-09-141-5/+4
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* Pass DynFlags down to wordWidthIan Lynagh2012-09-121-1/+1
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* Pass DynFlags down to bWordIan Lynagh2012-09-121-2/+2
| | | | | | I've switched to passing DynFlags rather than Platform, as (a) it's simpler to not have to extract targetPlatform in so many places, and (b) it may be useful to have DynFlags around in future.
* Add "Unregisterised" as a field in the settings fileIan Lynagh2012-08-071-2/+4
| | | | | | To explicitly choose whether you want an unregisterised build you now need to use the "--enable-unregisterised"/"--disable-unregisterised" configure flags.
* Make tablesNextToCode "dynamic"Ian Lynagh2012-08-061-3/+4
| | | | | This is a bit odd by itself, but it's a stepping stone on the way to putting "target unregisterised" into the settings file.
* Make -fscc-profiling a dynamic flagIan Lynagh2012-07-241-19/+20
| | | | All the flags that 'ways' imply are now dynamic
* Make -fPIC a dynamic flagIan Lynagh2012-07-161-8/+9
| | | | | | Hopefully I've kept the logic the same, and we now generate warnings if the user does -fno-PIC but we ignore them (e.g. because they're on OS X amd64).
* Remove PlatformOutputableIan Lynagh2012-06-131-2/+1
| | | | | We can now get the Platform from the DynFlags inside an SDoc, so we no longer need to pass the Platform in.
* Support code generation for unboxed-tuple function argumentsunboxed-tuple-arguments2Max Bolingbroke2012-05-151-4/+4
| | | | | | | | | | | This is done by a 'unarisation' pre-pass at the STG level which translates away all (live) binders binding something of unboxed tuple type. This has the following knock-on effects: * The subkind hierarchy is vastly simplified (no UbxTupleKind or ArgKind) * Various relaxed type checks in typechecker, 'foreign import prim' etc * All case binders may be live at the Core level
* Track STG live register information for use in LLVMDavid Terei2012-01-091-5/+8
| | | | | | | | | We now carry around with CmmJump statements a list of the STG registers that are live at that jump site. This is used by the LLVM backend so it can avoid unnesecarily passing around dead registers, improving perfromance. This gives us the framework to finally fix trac #4308.
* Remove unused argument field on CmmJumpDavid Terei2012-01-051-2/+2
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* Overhaul of infrastructure for profiling, coverage (HPC) and breakpointsSimon Marlow2011-11-021-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | User visible changes ==================== Profilng -------- Flags renamed (the old ones are still accepted for now): OLD NEW --------- ------------ -auto-all -fprof-auto -auto -fprof-exported -caf-all -fprof-cafs New flags: -fprof-auto Annotates all bindings (not just top-level ones) with SCCs -fprof-top Annotates just top-level bindings with SCCs -fprof-exported Annotates just exported bindings with SCCs -fprof-no-count-entries Do not maintain entry counts when profiling (can make profiled code go faster; useful with heap profiling where entry counts are not used) Cost-centre stacks have a new semantics, which should in most cases result in more useful and intuitive profiles. If you find this not to be the case, please let me know. This is the area where I have been experimenting most, and the current solution is probably not the final version, however it does address all the outstanding bugs and seems to be better than GHC 7.2. Stack traces ------------ +RTS -xc now gives more information. If the exception originates from a CAF (as is common, because GHC tends to lift exceptions out to the top-level), then the RTS walks up the stack and reports the stack in the enclosing update frame(s). Result: +RTS -xc is much more useful now - but you still have to compile for profiling to get it. I've played around a little with adding 'head []' to GHC itself, and +RTS -xc does pinpoint the problem quite accurately. I plan to add more facilities for stack tracing (e.g. in GHCi) in the future. Coverage (HPC) -------------- * derived instances are now coloured yellow if they weren't used * likewise record field names * entry counts are more accurate (hpc --fun-entry-count) * tab width is now correct (markup was previously off in source with tabs) Internal changes ================ In Core, the Note constructor has been replaced by Tick (Tickish b) (Expr b) which is used to represent all the kinds of source annotation we support: profiling SCCs, HPC ticks, and GHCi breakpoints. Depending on the properties of the Tickish, different transformations apply to Tick. See CoreUtils.mkTick for details. Tickets ======= This commit closes the following tickets, test cases to follow: - Close #2552: not a bug, but the behaviour is now more intuitive (test is T2552) - Close #680 (test is T680) - Close #1531 (test is result001) - Close #949 (test is T949) - Close #2466: test case has bitrotted (doesn't compile against current version of vector-space package)
* Remove a little more CPPIan Lynagh2011-10-151-4/+2
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* de-CPP codeGen/CgCon.lhsIan Lynagh2011-10-141-15/+24
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* Whitespace only in codeGen/CgCon.lhsIan Lynagh2011-10-141-205/+205
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* More CPP removal: pprDynamicLinkerAsmLabel in CLabelIan Lynagh2011-10-021-2/+4
| | | | And some knock-on changes
* Renaming onlySimon Peyton Jones2011-08-251-1/+1
| | | | | CmmTop -> CmmDecl CmmPgm -> CmmGroup
* Snapshot of codegen refactoring to share with simonpjSimon Marlow2011-08-251-2/+2
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* Merge in new code generator branch.Simon Marlow2011-01-241-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | This changes the new code generator to make use of the Hoopl package for dataflow analysis. Hoopl is a new boot package, and is maintained in a separate upstream git repository (as usual, GHC has its own lagging darcs mirror in http://darcs.haskell.org/packages/hoopl). During this merge I squashed recent history into one patch. I tried to rebase, but the history had some internal conflicts of its own which made rebase extremely confusing, so I gave up. The history I squashed was: - Update new codegen to work with latest Hoopl - Add some notes on new code gen to cmm-notes - Enable Hoopl lag package. - Add SPJ note to cmm-notes - Improve GC calls on new code generator. Work in this branch was done by: - Milan Straka <fox@ucw.cz> - John Dias <dias@cs.tufts.edu> - David Terei <davidterei@gmail.com> Edward Z. Yang <ezyang@mit.edu> merged in further changes from GHC HEAD and fixed a few bugs.
* Use opt_PIC not #defined __PIC__ in compiler source.Ben.Lippmeier@anu.edu.au2009-11-171-2/+6
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* Don't share low valued Int and Char closures with Windows DLLsBen.Lippmeier@anu.edu.au2009-11-141-0/+8
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* * Refactor CLabel.RtsLabel to CLabel.CmmLabelBen.Lippmeier@anu.edu.au2009-11-061-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The type of the CmmLabel ctor is now CmmLabel :: PackageId -> FastString -> CmmLabelInfo -> CLabel - When you construct a CmmLabel you have to explicitly say what package it is in. Many of these will just use rtsPackageId, but I've left it this way to remind people not to pretend labels are in the RTS package when they're not. - When parsing a Cmm file, labels that are not defined in the current file are assumed to be in the RTS package. Labels imported like import label are assumed to be in a generic "foreign" package, which is different from the current one. Labels imported like import "package-name" label are marked as coming from the named package. This last one is needed for the integer-gmp library as we want to refer to labels that are not in the same compilation unit, but are in the same non-rts package. This should help remove the nasty #ifdef __PIC__ stuff from integer-gmp/cbits/gmp-wrappers.cmm
* Merge RtsLabelInfo.Rts* with RtsLabelInfo.Rts*FSBen.Lippmeier@anu.edu.au2009-10-181-2/+2
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* Remove unused importsIan Lynagh2009-07-071-2/+0
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* Support for -fwarn-unused-do-bind and -fwarn-wrong-do-bind, as per #3263Max Bolingbroke2009-07-011-1/+1
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* FIX biographical profiling (#3039, probably #2297)Simon Marlow2009-03-171-3/+12
| | | | | | | | | Since we introduced pointer tagging, we no longer always enter a closure to evaluate it. However, the biographical profiler relies on closures being entered in order to mark them as "used", so we were getting spurious amounts of data attributed to VOID. It turns out there are various places that need to be fixed, and I think at least one of them was also wrong before pointer tagging (CgCon.cgReturnDataCon).
* Fix warnings in CgConIan Lynagh2008-12-291-11/+4
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* Merging in the new codegen branchdias@eecs.harvard.edu2008-08-141-7/+8
| | | | | | | | | | | | | | | | | | This merge does not turn on the new codegen (which only compiles a select few programs at this point), but it does introduce some changes to the old code generator. The high bits: 1. The Rep Swamp patch is finally here. The highlight is that the representation of types at the machine level has changed. Consequently, this patch contains updates across several back ends. 2. The new Stg -> Cmm path is here, although it appears to have a fair number of bugs lurking. 3. Many improvements along the CmmCPSZ path, including: o stack layout o some code for infotables, half of which is right and half wrong o proc-point splitting
* (F)SLIT -> (f)sLit in CgConIan Lynagh2008-04-121-2/+2
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* Don't import FastString in HsVersions.hIan Lynagh2008-03-291-0/+1
| | | | Modules that need it import it themselves instead.
* Make various assertions work when !DEBUGIan Lynagh2007-09-081-3/+1
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* massive changes to add a 'zipper' representation of C--Norman Ramsey2007-09-061-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Changes too numerous to comment on, but here is some old history that I saved: Wed Aug 15 11:07:13 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * type synonyms made consistent with new Cmm types M ./compiler/nativeGen/MachInstrs.hs -2 +2 Mon Aug 20 19:22:14 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * pushing return info beyond cmm into codegen M ./compiler/codeGen/Bitmap.hs r3 M ./compiler/codeGen/CgBindery.lhs r3 M ./compiler/codeGen/CgCallConv.hs r3 M ./compiler/codeGen/CgCase.lhs r3 M ./compiler/codeGen/CgClosure.lhs r3 M ./compiler/codeGen/CgCon.lhs r3 M ./compiler/codeGen/CgExpr.lhs r3 M ./compiler/codeGen/CgForeignCall.hs -6 +7 r3 M ./compiler/codeGen/CgHeapery.lhs r3 M ./compiler/codeGen/CgHpc.hs +1 r3 M ./compiler/codeGen/CgInfoTbls.hs r3 M ./compiler/codeGen/CgLetNoEscape.lhs r3 M ./compiler/codeGen/CgMonad.lhs r3 M ./compiler/codeGen/CgParallel.hs r3 M ./compiler/codeGen/CgPrimOp.hs +3 r3 M ./compiler/codeGen/CgProf.hs r3 M ./compiler/codeGen/CgStackery.lhs r3 M ./compiler/codeGen/CgTailCall.lhs r3 M ./compiler/codeGen/CgTicky.hs r3 M ./compiler/codeGen/CgUtils.hs -1 +1 r3 M ./compiler/codeGen/ClosureInfo.lhs r3 M ./compiler/codeGen/CodeGen.lhs r3 M ./compiler/codeGen/SMRep.lhs r3 M ./compiler/nativeGen/AsmCodeGen.lhs -2 +2 r1 M ./compiler/nativeGen/MachCodeGen.hs -3 +3 r1 M ./compiler/nativeGen/MachInstrs.hs r1 M ./compiler/nativeGen/MachRegs.lhs r1 M ./compiler/nativeGen/NCGMonad.hs r1 M ./compiler/nativeGen/PositionIndependentCode.hs r1 M ./compiler/nativeGen/PprMach.hs r1 M ./compiler/nativeGen/RegAllocInfo.hs r1 M ./compiler/nativeGen/RegisterAlloc.hs r1 Mon Aug 20 20:54:41 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * put CmmReturnInfo into a CmmCall (and related types) M ./compiler/cmm/Cmm.hs -2 +1 r3 M ./compiler/cmm/CmmBrokenBlock.hs -13 +12 r1 M ./compiler/cmm/CmmCPS.hs -3 +3 M ./compiler/cmm/CmmCPSGen.hs -8 +6 r1 M ./compiler/cmm/CmmLint.hs -1 +1 M ./compiler/cmm/CmmLive.hs -1 +1 M ./compiler/cmm/CmmOpt.hs -3 +3 M ./compiler/cmm/CmmParse.y -6 +6 r3 M ./compiler/cmm/PprC.hs -3 +3 M ./compiler/cmm/PprCmm.hs -7 +4 r2 M ./compiler/codeGen/CgForeignCall.hs -7 +6 r2 M ./compiler/codeGen/CgHpc.hs -1 r1 M ./compiler/codeGen/CgPrimOp.hs -3 r1 M ./compiler/codeGen/CgUtils.hs -1 +1 r1 M ./compiler/nativeGen/AsmCodeGen.lhs -2 +2 M ./compiler/nativeGen/MachCodeGen.hs -3 +3 r1 Tue Aug 21 18:09:13 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * add call info in nativeGen M ./compiler/nativeGen/AsmCodeGen.lhs r1 M ./compiler/nativeGen/MachInstrs.hs r1 M ./compiler/nativeGen/MachRegs.lhs r1 M ./compiler/nativeGen/NCGMonad.hs r1 M ./compiler/nativeGen/PositionIndependentCode.hs r1 M ./compiler/nativeGen/PprMach.hs r1 M ./compiler/nativeGen/RegAllocInfo.hs r1 Wed Aug 22 16:41:58 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * ListGraph is now a newtype, not a synonym The resultant bookkeepping is unenviable, but the change greatly simplifies our ability to make Cmm things propertly Outputable for both list-graph and zipper-graph representations. M ./compiler/cmm/Cmm.hs -5 +3 M ./compiler/cmm/CmmCPS.hs -2 +2 M ./compiler/cmm/CmmCPSGen.hs -1 +1 M ./compiler/cmm/CmmContFlowOpt.hs -3 +3 M ./compiler/cmm/CmmCvt.hs -2 +2 M ./compiler/cmm/CmmInfo.hs -2 +3 M ./compiler/cmm/CmmLint.hs -1 +1 M ./compiler/cmm/CmmOpt.hs -2 +2 M ./compiler/cmm/PprC.hs -1 +1 M ./compiler/cmm/PprCmm.hs -5 +8 M ./compiler/cmm/PprCmmZ.hs -7 +1 M ./compiler/codeGen/CgMonad.lhs -1 +1 M ./compiler/nativeGen/AsmCodeGen.lhs -15 +15 M ./compiler/nativeGen/MachCodeGen.hs -2 +2 M ./compiler/nativeGen/PositionIndependentCode.hs -6 +6 M ./compiler/nativeGen/PprMach.hs -3 +2 M ./compiler/nativeGen/RegAllocColor.hs +1 M ./compiler/nativeGen/RegAllocLinear.hs -4 +5 M ./compiler/nativeGen/RegCoalesce.hs -6 +6 M ./compiler/nativeGen/RegLiveness.hs -12 +12 Thu Aug 23 13:44:49 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * diagnostic assistance in case fromJust fails M ./compiler/nativeGen/MachCodeGen.hs -2 +5 Thu Aug 23 14:07:28 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * give every block, even the first, a label With branch-chain elimination, the first block of a procedure might be the target of a branch. This actually happens to a dozen or more procedures in the run-time system. M ./compiler/nativeGen/PprMach.hs -8 +3 Fri Aug 24 17:27:04 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * clean up the code in PprMach M ./compiler/nativeGen/PprMach.hs -16 +14 Fri Aug 24 19:35:03 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * a bunch of impedance matching to get the compiler to build, plus * the plus is diagnostics for unreachable code, which required moving a lot of prettyprinting code M ./compiler/cmm/Cmm.hs -7 +5 M ./compiler/cmm/CmmCPSZ.hs -1 +1 M ./compiler/cmm/CmmCvt.hs -8 +8 M ./compiler/cmm/CmmParse.y -4 +3 M ./compiler/cmm/MkZipCfg.hs -19 +9 M ./compiler/cmm/PprCmmZ.hs -118 +4 M ./compiler/cmm/ZipCfg.hs -1 +13 M ./compiler/cmm/ZipCfgCmm.hs -10 +129 M ./compiler/main/HscMain.lhs -4 +4 M ./compiler/nativeGen/NCGMonad.hs -2 +2 M ./compiler/nativeGen/RegAllocInfo.hs -3 +3 Fri Aug 31 14:38:02 BST 2007 Norman Ramsey <nr@eecs.harvard.edu> * fix a warning about an import M ./compiler/nativeGen/RegAllocColor.hs -1 +1
* Fix CodingStyle#Warnings URLsIan Lynagh2007-09-041-1/+1
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* Use OPTIONS rather than OPTIONS_GHC for pragmasIan Lynagh2007-09-031-2/+2
| | | | | | | Older GHCs can't parse OPTIONS_GHC. This also changes the URL referenced for the -w options from WorkingConventions#Warnings to CodingStyle#Warnings for the compiler modules.
* Add {-# OPTIONS_GHC -w #-} and some blurb to all compiler modulesIan Lynagh2007-09-011-0/+7
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* Change the strategy to determine dynamic data accessClemens Fruhwirth2007-07-311-13/+10
| | | | | | | | | | | | | Instead of attaching the information whether a Label is going to be accessed dynamically or not (distinction between IdLabel/DynLabel and additional flags in ModuleInitLabel and PlainModuleInitLabel), we hand dflags through the CmmOpt monad and the NatM monad. Before calling labelDynamic in PositionIndependentCode, we extract thisPackage from dflags and supply the current package to labelDynamic, so it can take this information into account instead of extracting it from the labels itself. This simplifies a lot of code in codeGen that just hands through this_pkg.
* Pointer TaggingSimon Marlow2007-07-271-9/+18
| | | | | | | | | | | | | | | | | | | | | | This patch implements pointer tagging as per our ICFP'07 paper "Faster laziness using dynamic pointer tagging". It improves performance by 10-15% for most workloads, including GHC itself. The original patches were by Alexey Rodriguez Yakushev <mrchebas@gmail.com>, with additions and improvements by me. I've re-recorded the development as a single patch. The basic idea is this: we use the low 2 bits of a pointer to a heap object (3 bits on a 64-bit architecture) to encode some information about the object pointed to. For a constructor, we encode the "tag" of the constructor (e.g. True vs. False), for a function closure its arity. This enables some decisions to be made without dereferencing the pointer, which speeds up some common operations. In particular it enables us to avoid costly indirect jumps in many cases. More information in the commentary: http://hackage.haskell.org/trac/ghc/wiki/Commentary/Rts/HaskellExecution/PointerTagging
* Remove vectored returns.Simon Marlow2007-02-281-5/+3
| | | | | We recently discovered that they aren't a win any more, and just cost code size.
* Module header tidyup, phase 1Simon Marlow2006-10-111-30/+21
| | | | | | | | | | | | This patch is a start on removing import lists and generally tidying up the top of each module. In addition to removing import lists: - Change DATA.IOREF -> Data.IORef etc. - Change List -> Data.List etc. - Remove $Id$ - Update copyrights - Re-order imports to put non-GHC imports last - Remove some unused and duplicate imports
* Generalise Package SupportSimon Marlow2006-07-251-13/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch pushes through one fundamental change: a module is now identified by the pair of its package and module name, whereas previously it was identified by its module name alone. This means that now a program can contain multiple modules with the same name, as long as they belong to different packages. This is a language change - the Haskell report says nothing about packages, but it is now necessary to understand packages in order to understand GHC's module system. For example, a type T from module M in package P is different from a type T from module M in package Q. Previously this wasn't an issue because there could only be a single module M in the program. The "module restriction" on combining packages has therefore been lifted, and a program can contain multiple versions of the same package. Note that none of the proposed syntax changes have yet been implemented, but the architecture is geared towards supporting import declarations qualified by package name, and that is probably the next step. It is now necessary to specify the package name when compiling a package, using the -package-name flag (which has been un-deprecated). Fortunately Cabal still uses -package-name. Certain packages are "wired in". Currently the wired-in packages are: base, haskell98, template-haskell and rts, and are always referred to by these versionless names. Other packages are referred to with full package IDs (eg. "network-1.0"). This is because the compiler needs to refer to entities in the wired-in packages, and we didn't want to bake the version of these packages into the comiler. It's conceivable that someone might want to upgrade the base package independently of GHC. Internal changes: - There are two module-related types: ModuleName just a FastString, the name of a module Module a pair of a PackageId and ModuleName A mapping from ModuleName can be a UniqFM, but a mapping from Module must be a FiniteMap (we provide it as ModuleEnv). - The "HomeModules" type that was passed around the compiler is now gone, replaced in most cases by the current package name which is contained in DynFlags. We can tell whether a Module comes from the current package by comparing its package name against the current package. - While I was here, I changed PrintUnqual to be a little more useful: it now returns the ModuleName that the identifier should be qualified with according to the current scope, rather than its original module. Also, PrintUnqual tells whether to qualify module names with package names (currently unused). Docs to follow.
* unused importSimon Marlow2006-07-061-1/+0
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* Reorganisation of the source treeSimon Marlow2006-04-071-0/+457
Most of the other users of the fptools build system have migrated to Cabal, and with the move to darcs we can now flatten the source tree without losing history, so here goes. The main change is that the ghc/ subdir is gone, and most of what it contained is now at the top level. The build system now makes no pretense at being multi-project, it is just the GHC build system. No doubt this will break many things, and there will be a period of instability while we fix the dependencies. A straightforward build should work, but I haven't yet fixed binary/source distributions. Changes to the Building Guide will follow, too.