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This copies the subset of Hoopl's functionality needed by GHC to
`cmm/Hoopl` and removes the dependency on the Hoopl package.

The main motivation for this change is the confusing/noisy interface
between GHC and Hoopl:
- Hoopl has `Label` which is GHC's `BlockId` but different than
  GHC's `CLabel`
- Hoopl has `Unique` which is different than GHC's `Unique`
- Hoopl has `Unique{Map,Set}` which are different than GHC's
  `Uniq{FM,Set}`
- GHC has its own specialized copy of `Dataflow`, so `cmm/Hoopl` is
  needed just to filter the exposed functions (filter out some of the
  Hoopl's and add the GHC ones)
With this change, we'll be able to simplify this significantly.
It'll also be much easier to do invasive changes (Hoopl is a public
package on Hackage with users that depend on the current behavior)

This should introduce no changes in functionality - it merely
copies the relevant code.
Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

Test Plan: ./validate

Reviewers: austin, bgamari, simonmar

Reviewed By: bgamari, simonmar

Subscribers: simonpj, kavon, rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3616

This change is requred for llvm 4.0. GHC doesn't use that version yet,
but this change is just as valid for versions eariler than 4.0.

Two changes needed:

* Previously, GHC defined a `topN` node in the TBAA heiarchy and some IR
  instructions referenced that node. With LLVM 4.0 the root node can no
  longer be referenced by IR instructions, so we introduce a new element
  `rootN` and make `topN` a child of that.

* Previously the root TBAA node was rendered as "!0 = !{!"root", null}".
  With LLVM 4.0 that needs to be "!0 = !{!"root"}" which is also
  accepted by earlier versions.

Test Plan: Build with quick-llvm BuildFlavor and run tests

Reviewers: bgamari, drbo, austin, angerman, michalt, DemiMarie

Reviewed By: DemiMarie

Subscribers: mpickering, DemiMarie, thomie

Differential Revision: https://phabricator.haskell.org/D2975

These were previously just represented as Ints which was needlessly
vague.

This adds timings and allocation figures to the compiler's output when
run with `-v2` in an effort to ease performance analysis.

Todo:
  * Documentation
  * Where else should we add these?
  * Perhaps we should remove some of the now-arguably-redundant
    `showPass` occurrences where they are
  * Must we force more?
  * Perhaps we should place this behind a `-ftimings` instead of `-v2`

Test Plan: `ghc -v2 Test.hs`, look at the output

Reviewers: hvr, goldfire, simonmar, austin

Reviewed By: simonmar

Subscribers: angerman, michalt, niteria, ezyang, thomie

Differential Revision: https://phabricator.haskell.org/D1959

Commit 673efccb uncovered a bug in LLVM code generation that produced
LLVM code that the LLVM compiler refused to compile:

    {
    clpH:
      br label %clpH
    }

This may well be a bug in LLVM itself. The solution is to keep the
existing entry label and rewrite the function as:

    {
    clpH:
      br label %nPV
    nPV:
      br label %nPV
    }

Thanks to Ben Gamari for pointing me in the right direction on this
one.

Test Plan: Build GHC with BuildFlavour=quick-llvm

Reviewers: hvr, austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1996

GHC Trac Issues: #11649

Summary:
Before:

    [1 of 1] Compiling Main             ( Main.hs, Main.o )
    You are using a new version of LLVM that hasn't been tested yet!
    We will try though...

After:

    [1 of 1] Compiling Main             ( Main.hs, Main.o )
    You are using an unsupported version of LLVM!
    Currently only 3.7 is supported.
    We will try though...

Before:

    [1 of 1] Compiling Main             ( Main.hs, Main.o )

    <no location info>:
        Warning: Couldn't figure out LLVM version!
                 Make sure you have installed LLVM
    ghc: could not execute: opt

After:

    [1 of 1] Compiling Main             ( Main.hs, Main.o )

    <no location info>: error:
        Warning: Couldn't figure out LLVM version!
                 Make sure you have installed LLVM 3.7
    ghc-stage1: could not execute: opt

Reviewers: austin, rwbarton, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1658

Before this commit, GHC only supported LLVM 3.6. Now it only supports
LLVM 3.7 which was released in August 2015. LLVM version 3.6 and earlier
do not work on AArch64/Arm64, but 3.7 does.

Also:
* Add CC_Ghc constructor to LlvmCallConvention.
* Replace `maxSupportLlvmVersion`/`minSupportLlvmVersion` with
  a single `supportedLlvmVersion` variable.
* Get `supportedLlvmVersion` from version specified in configure.ac.
* Drop llvmVersion field from DynFlags (no longer needed because only
  one version is supported).

Test Plan: Validate on x86_64 and arm

Reviewers: bgamari, austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1320

GHC Trac Issues: #10953

Pushed by mistacke before it was ready.

This reverts commit 5dc3db74.

Summary:
Rework llvmGen to use LLVM 3.6 exclusively. The plans for the 7.12 release are to ship LLVM alongside GHC in the interests of user (and developer) sanity.

Along the way, refactor TNTC support to take advantage of the new `prefix` data support in LLVM 3.6. This allows us to drop the section-reordering component of the LLVM mangler.

Test Plan: Validate, look at emitted code

Reviewers: dterei, austin, scpmw

Reviewed By: austin

Subscribers: erikd, awson, spacekitteh, thomie, carter

Differential Revision: https://phabricator.haskell.org/D530

GHC Trac Issues: #10074

Due to changes in LLVM 3.5 aliases now may only refer to definitions.
Previously to handle symbols defined outside of the current commpilation
unit GHC would emit both an `external` declaration, as well as an alias
pointing to it, e.g.,

    @stg_BCO_info = external global i8
    @stg_BCO_info$alias = alias private i8* @stg_BCO_info

Where references to `stg_BCO_info` will use the alias
`stg_BCO_info$alias`. This is not permitted under the new alias
behavior, resulting in errors resembling,

    Alias must point to a definition
    i8* @"stg_BCO_info$alias"

To fix this, we invert the naming relationship between aliases and
definitions. That is, now the symbol definition takes the name
`@stg_BCO_info$def` and references use the actual name, `@stg_BCO_info`.
This means the external symbols can be handled by simply emitting an
`external` declaration,

    @stg_BCO_info = external global i8

Whereas in the case of a forward declaration we emit,

    @stg_BCO_info = alias private i8* @stg_BCO_info$def

Reviewed By: austin

Differential Revision: https://phabricator.haskell.org/D155

In some cases, the layout of the LANGUAGE/OPTIONS_GHC lines has been
reorganized, while following the convention, to

- place `{-# LANGUAGE #-}` pragmas at the top of the source file, before
  any `{-# OPTIONS_GHC #-}`-lines.

- Moreover, if the list of language extensions fit into a single
  `{-# LANGUAGE ... -#}`-line (shorter than 80 characters), keep it on one
  line. Otherwise split into `{-# LANGUAGE ... -#}`-lines for each
  individual language extension. In both cases, try to keep the
  enumeration alphabetically ordered.
  (The latter layout is preferable as it's more diff-friendly)

While at it, this also replaces obsolete `{-# OPTIONS ... #-}` pragma
occurences by `{-# OPTIONS_GHC ... #-}` pragmas.

This checks that all the required extensions are enabled for the
inferred type signature.

Updates binary and vector submodules.

Slightly more documentation, removed unused label map (huh),
removed MonadIO instance on LlvmM to improve encapsulation.

This combined patch reworks the LLVM backend in a number of ways:

1. Most prominently, we introduce a LlvmM monad carrying the contents of
   the old LlvmEnv around. This patch completely removes LlvmEnv and
   refactors towards standard library monad combinators wherever possible.

2. Support for streaming - we can now generate chunks of Llvm for Cmm as
   it comes in. This might improve our speed.

3. To allow streaming, we need a more flexible way to handle forward
   references. The solution (getGlobalPtr) unifies LlvmCodeGen.Data
   and getHsFunc as well.

4. Skip alloca-allocation for registers that are actually never written.
   LLVM will automatically eliminate these, but output is smaller and
   friendlier to human eyes this way.

5. We use LlvmM to collect references for llvm.used. This allows places
   other than cmmProcLlvmGens to generate entries.

Also give them a proper constructor - getGlobalVar and getGlobalValue
map directly to the accessors.

LLVM 3.3rc3 complains when the llvm.used global is an empty array, so don't
define llvm.used at all when it would be empty.

This controls whether or not the compiler warns if we're using an LLVM
version that's too old or too new. It's mostly useful when building the
compiler knowingly with an unsupported version, so you don't get a lot
of warnings in the build process.

There's no documentation for this since it's a flag only a few
developers would care about anyway.
Signed-off-by: Austin Seipp <mad.one@gmail.com>

This removes the OldCmm data type and the CmmCvt pass that converts
new Cmm to OldCmm.  The backends (NCGs, LLVM and C) have all been
converted to consume new Cmm.

The main difference between the two data types is that conditional
branches in new Cmm have both true/false successors, whereas in OldCmm
the false case was a fallthrough.  To generate slightly better code we
occasionally need to invert a conditional to ensure that the
branch-not-taken becomes a fallthrough; this was previously done in
CmmCvt, and it is now done in CmmContFlowOpt.

We could go further and use the Hoopl Block representation for native
code, which would mean that we could use Hoopl's postorderDfs and
analyses for native code, but for now I've left it as is, using the
old ListGraph representation for native code.

We now have accurate global register liveness information attached to all Cmm
procedures and jumps. With this patch, the LLVM back end uses this information
to pass only the live floating point (F and D) registers on tail calls. This
makes the LLVM back end compatible with the new register allocation strategy.

Ideally the GHC LLVM calling convention would put all registers that are always
live first in the parameter sequence. Unfortunately the specification is written
so that on x86-64 SpLim (always live) is passed after the R registers. Therefore
we must always pass *something* in the R registers, so we pass the LLVM value
undef.

All Cmm procedures now include the set of global registers that are live on
procedure entry, i.e., the global registers used to pass arguments to the
procedure. Only global registers that are use to pass arguments are included in
this list.

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.

To explicitly choose whether you want an unregisterised build you now
need to use the "--enable-unregisterised"/"--disable-unregisterised"
configure flags.

Proc-point splitting is only required by backends that do not support
having proc-points within a code block (that is, everything except the
native backend, i.e. LLVM and C).

Not doing proc-point splitting saves some compilation time, and might
produce slightly better code in some cases.

In particular, this makes life simpler when we want to use a general
GHC SDoc in the middle of some LLVM.

is used for optimisation. (enabled by default)

Compile time still isn't as good as I'd like but no easy changes
available. LLVM backend could do with a big rewrite to improve
performance as there are some ugly designs in it.

At least the test case isn't 10min anymore, just a few seconds now.

And some knock-on changes

   CmmTop -> CmmDecl
   CmmPgm -> CmmGroup