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13527 commits behind the upstream repository.
Artem Pyanykh's avatar
Artem Pyanykh authored
Zero size sections are common even during regular build on MacOS. For
instance:

```
$ ar -xv libHSghc-prim-0.6.1.a longlong.o
$ otool -l longlong.o
longlong.o:
Mach header
      magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
 0xfeedfacf 16777223          3  0x00           1     2        176 0x00002000
Load command 0
      cmd LC_SEGMENT_64
  cmdsize 152
  segname
   vmaddr 0x0000000000000000
   vmsize 0x0000000000000000 <-- segment size = 0
  fileoff 208
 filesize 0
  maxprot 0x00000007
 initprot 0x00000007
   nsects 1
    flags 0x0
Section
  sectname __text
   segname __TEXT
      addr 0x0000000000000000
      size 0x0000000000000000 <-- section size = 0
    offset 208
     align 2^0 (1)
    reloff 0
    nreloc 0
     flags 0x80000000
 reserved1 0
 reserved2 0
       cmd LC_BUILD_VERSION
   cmdsize 24
  platform macos
       sdk 10.14
     minos 10.14
    ntools 0
```

The issue of `mmap`ing 0 bytes was resolved in !1050, but the problem
remained. These 0 size segments and sections were still allocated in
object code, which lead to failed `ASSERT(size > 0)` in
`addProddableBlock` further down the road.

With this change zero size segments **and** sections are not
mapped/allocated at all.

Test plan:

1. Build statically linked GHC.

2. Run `ghc --interactive`. Observe that REPL loads
successfully (which was not the case before).

3. Load several more compiled hs files into repl. No failures.
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The Glasgow Haskell Compiler

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This is the source tree for GHC, a compiler and interactive environment for the Haskell functional programming language.

For more information, visit GHC's web site.

Information for developers of GHC can be found on the GHC issue tracker.

Getting the Source

There are two ways to get a source tree:

  1. Download source tarballs

    Download the GHC source distribution:

    ghc-<version>-src.tar.xz

    which contains GHC itself and the "boot" libraries.

  2. Check out the source code from git

    $ git clone --recursive git@gitlab.haskell.org:ghc/ghc.git

    Note: cloning GHC from Github requires a special setup. See Getting a GHC repository from Github.

See the GHC team's working conventions regarding how to contribute a patch to GHC. First time contributors are encouraged to get started by just sending a Merge Request.

Building & Installing

For full information on building GHC, see the GHC Building Guide. Here follows a summary - if you get into trouble, the Building Guide has all the answers.

Before building GHC you may need to install some other tools and libraries. See, Setting up your system for building GHC.

NB. In particular, you need GHC installed in order to build GHC, because the compiler is itself written in Haskell. You also need Happy, Alex, and Cabal. For instructions on how to port GHC to a new platform, see the GHC Building Guide.

For building library documentation, you'll need Haddock. To build the compiler documentation, you need Sphinx and Xelatex (only for PDF output).

Quick start: the following gives you a default build:

$ ./boot
$ ./configure
$ make         # can also say 'make -jX' for X number of jobs
$ make install

On Windows, you need an extra repository containing some build tools. These can be downloaded for you by configure. This only needs to be done once by running:

$ ./configure --enable-tarballs-autodownload

(NB: Do you have multiple cores? Be sure to tell that to make! This can save you hours of build time depending on your system configuration, and is almost always a win regardless of how many cores you have. As a simple rule, you should have about N+1 jobs, where N is the amount of cores you have.)

The ./boot step is only necessary if this is a tree checked out from git. For source distributions downloaded from GHC's web site, this step has already been performed.

These steps give you the default build, which includes everything optimised and built in various ways (eg. profiling libs are built). It can take a long time. To customise the build, see the file HACKING.md.

Filing bugs and feature requests

If you've encountered what you believe is a bug in GHC, or you'd like to propose a feature request, please let us know! Submit an issue and we'll be sure to look into it. Remember: Filing a bug is the best way to make sure your issue isn't lost over time, so please feel free.

If you're an active user of GHC, you may also be interested in joining the glasgow-haskell-users mailing list, where developers and GHC users discuss various topics and hang out.

Hacking & Developing GHC

Once you've filed a bug, maybe you'd like to fix it yourself? That would be great, and we'd surely love your company! If you're looking to hack on GHC, check out the guidelines in the HACKING.md file in this directory - they'll get you up to speed quickly.

Contributors & Acknowledgements

GHC in its current form wouldn't exist without the hard work of its many contributors. Over time, it has grown to include the efforts and research of many institutions, highly talented people, and groups from around the world. We'd like to thank them all, and invite you to join!