summaryrefslogtreecommitdiff
path: root/compiler/llvmGen/LlvmCodeGen/CodeGen.hs
Commit message (Collapse)AuthorAgeFilesLines
* Modules: Llvm (#13009)Sylvain Henry2020-02-181-1995/+0
|
* Disable two warnings for files that trigger themTom Ellis2020-01-271-0/+1
| | | | | | incomplete-uni-patterns and incomplete-record-updates will be in -Wall at a future date, so prepare for that by disabling those warnings on files that trigger them.
* Module hierarchy: Cmm (cf #13009)Sylvain Henry2020-01-251-9/+9
|
* llvmGen: Fix #14251Ben Gamari2020-01-201-12/+10
| | | | | | | | | | | | | | Fixes the calling convention for functions passing raw SSE-register values by adding padding as needed to get the values in the right registers. This problem cropped up when some args were unused an dropped from the live list. This folds together 2e23e1c7de01c92b038e55ce53d11bf9db993dd4 and 73273be476a8cc6c13368660b042b3b0614fd928 previously from @kavon. Metric Increase: T12707 ManyConstructors
* llvmGen: Don't trash STG registersBen Gamari2020-01-201-38/+2
| | | | Fixes #13904.
* Fix more typos, via an improved Levenshtein-style correctorBrian Wignall2020-01-121-1/+1
|
* llvmGen: Ensure that entry labels don't have predecessorsBen Gamari2019-12-301-7/+14
| | | | | | | | | | The LLVM IR forbids the entry label of a procedure from having any predecessors. In the case of a simple looping function the LLVM code generator broke this invariant, as noted in #17589. Fix this by moving the function prologue to its own basic block, as suggested by @kavon in #11649. Fixes #11649 and #17589.
* Add `timesInt2#` primopSylvain Henry2019-12-021-0/+1
|
* Module hierarchy: StgToCmm (#13009)Sylvain Henry2019-09-101-1/+1
| | | | | | Add StgToCmm module hierarchy. Platform modules that are used in several other places (NCG, LLVM codegen, Cmm transformations) are put into GHC.Platform.
* Revert "Add support for SIMD operations in the NCG"Ben Gamari2019-07-161-5/+3
| | | | | | | Unfortunately this will require more work; register allocation is quite broken. This reverts commit acd795583625401c5554f8e04ec7efca18814011.
* Add support for SIMD operations in the NCGAbhiroop Sarkar2019-07-031-3/+5
| | | | | | | This adds support for constructing vector types from Float#, Double# etc and performing arithmetic operations on them Cleaned-Up-By: Ben Gamari <ben@well-typed.com>
* Correct closure observation, construction, and mutation on weak memory machines.Travis Whitaker2019-06-281-6/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here the following changes are introduced: - A read barrier machine op is added to Cmm. - The order in which a closure's fields are read and written is changed. - Memory barriers are added to RTS code to ensure correctness on out-or-order machines with weak memory ordering. Cmm has a new CallishMachOp called MO_ReadBarrier. On weak memory machines, this is lowered to an instruction that ensures memory reads that occur after said instruction in program order are not performed before reads coming before said instruction in program order. On machines with strong memory ordering properties (e.g. X86, SPARC in TSO mode) no such instruction is necessary, so MO_ReadBarrier is simply erased. However, such an instruction is necessary on weakly ordered machines, e.g. ARM and PowerPC. Weam memory ordering has consequences for how closures are observed and mutated. For example, consider a closure that needs to be updated to an indirection. In order for the indirection to be safe for concurrent observers to enter, said observers must read the indirection's info table before they read the indirectee. Furthermore, the entering observer makes assumptions about the closure based on its info table contents, e.g. an INFO_TYPE of IND imples the closure has an indirectee pointer that is safe to follow. When a closure is updated with an indirection, both its info table and its indirectee must be written. With weak memory ordering, these two writes can be arbitrarily reordered, and perhaps even interleaved with other threads' reads and writes (in the absence of memory barrier instructions). Consider this example of a bad reordering: - An updater writes to a closure's info table (INFO_TYPE is now IND). - A concurrent observer branches upon reading the closure's INFO_TYPE as IND. - A concurrent observer reads the closure's indirectee and enters it. (!!!) - An updater writes the closure's indirectee. Here the update to the indirectee comes too late and the concurrent observer has jumped off into the abyss. Speculative execution can also cause us issues, consider: - An observer is about to case on a value in closure's info table. - The observer speculatively reads one or more of closure's fields. - An updater writes to closure's info table. - The observer takes a branch based on the new info table value, but with the old closure fields! - The updater writes to the closure's other fields, but its too late. Because of these effects, reads and writes to a closure's info table must be ordered carefully with respect to reads and writes to the closure's other fields, and memory barriers must be placed to ensure that reads and writes occur in program order. Specifically, updates to a closure must follow the following pattern: - Update the closure's (non-info table) fields. - Write barrier. - Update the closure's info table. Observing a closure's fields must follow the following pattern: - Read the closure's info pointer. - Read barrier. - Read the closure's (non-info table) fields. This patch updates RTS code to obey this pattern. This should fix long-standing SMP bugs on ARM (specifically newer aarch64 microarchitectures supporting out-of-order execution) and PowerPC. This fixes issue #15449. Co-Authored-By: Ben Gamari <ben@well-typed.com>
* Move 'Platform' to ghc-bootJohn Ericson2019-06-191-1/+1
| | | | | | | ghc-pkg needs to be aware of platforms so it can figure out which subdire within the user package db to use. This is admittedly roundabout, but maybe Cabal could use the same notion of a platform as GHC to good affect too.
* Introduce log1p and expm1 primopschessai2019-06-091-0/+4
| | | | | Previously log and exp were primitives yet log1p and expm1 were FFI calls. Fix this non-uniformity.
* Add support for bitreverse primopAlexandre2019-04-011-4/+7
| | | | | | This commit includes the necessary changes in code and documentation to support a primop that reverses a word's bits. It also includes a test.
* Prepare source-tree for base-4.13 MFP bumpHerbert Valerio Riedel2019-01-181-2/+2
|
* Fix unused-import warningsDavid Eichmann2018-11-221-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes a fairly long-standing bug (dating back to 2015) in RdrName.bestImport, namely commit 9376249b6b78610db055a10d05f6592d6bbbea2f Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Wed Oct 28 17:16:55 2015 +0000 Fix unused-import stuff in a better way In that patch got the sense of the comparison back to front, and thereby failed to implement the unused-import rules described in Note [Choosing the best import declaration] in RdrName This led to Trac #13064 and #15393 Fixing this bug revealed a bunch of unused imports in libraries; the ones in the GHC repo are part of this commit. The two important changes are * Fix the bug in bestImport * Modified the rules by adding (a) in Note [Choosing the best import declaration] in RdrName Reason: the previosu rules made Trac #5211 go bad again. And the new rule (a) makes sense to me. In unravalling this I also ended up doing a few other things * Refactor RnNames.ImportDeclUsage to use a [GlobalRdrElt] for the things that are used, rather than [AvailInfo]. This is simpler and more direct. * Rename greParentName to greParent_maybe, to follow GHC naming conventions * Delete dead code RdrName.greUsedRdrName Bumps a few submodules. Reviewers: hvr, goldfire, bgamari, simonmar, jrtc27 Subscribers: rwbarton, carter Differential Revision: https://phabricator.haskell.org/D5312
* Revert "Multiple fixes / improvements for LLVM backend"Ben Gamari2018-11-071-11/+49
| | | | This reverts commit adcb5fb47c0942671d409b940d8884daa9359ca4.
* Revert "Fix for T14251 on ARM"Ben Gamari2018-11-071-3/+3
| | | | This reverts commit d8495549ba9d194815c2d0eaee6797fc7c00756a.
* [LlvmCodeGen] Fixes for Int8#/Word8#Michal Terepeta2018-11-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes two isssues: - Using bitcast for MO_XX_Conv Arguments to a bitcast must be of the same size. We should be using `trunc` and `zext` instead. - Using unsupported MO_*_QuotRem for LLVM The two primops `MO_*_QuotRem` are not supported by the LLVM backend, so we shouldn't use them for `Int8#`/`Word8#` (just as we do not use them for `Int#`/`Word#`). Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com> Test Plan: manually run tests with WAY=llvm Reviewers: bgamari, simonmar Reviewed By: bgamari Subscribers: rwbarton, carter GHC Trac Issues: #15864 Differential Revision: https://phabricator.haskell.org/D5304
* Add Int8# and Word8#Michal Terepeta2018-11-021-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the first step of implementing: https://github.com/ghc-proposals/ghc-proposals/pull/74 The main highlights/changes: primops.txt.pp gets two new sections for two new primitive types for signed and unsigned 8-bit integers (Int8# and Word8 respectively) along with basic arithmetic and comparison operations. PrimRep/RuntimeRep get two new constructors for them. All of the primops translate into the existing MachOPs. For CmmCalls the codegen will now zero-extend the values at call site (so that they can be moved to the right register) and then truncate them back their original width. x86 native codegen needed some updates, since it wasn't able to deal with the new widths, but all the changes are quite localized. LLVM backend seems to just work. This is the second attempt at merging this, after the first attempt in D4475 had to be backed out due to regressions on i386. Bumps binary submodule. Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com> Test Plan: ./validate (on both x86-{32,64}) Reviewers: bgamari, hvr, goldfire, simonmar Subscribers: rwbarton, carter Differential Revision: https://phabricator.haskell.org/D5258
* Fix for T14251 on ARMKavon Farvardin2018-10-281-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | We now calculate the SSE register padding needed to fix the calling convention in LLVM in a robust way: grouping them by whether registers in that class overlap (with the same class overlapping itself). My prior patch assumed that no matter the platform, physical register Fx aliases with Dx, etc, for our calling convention. This is unfortunately not the case for any platform except x86-64. Test Plan: Only know how to test on x86-64, but it should be tested on ARM with: `make test WAYS=llvm && make test WAYS=optllvm` Reviewers: bgamari, angerman Reviewed By: bgamari Subscribers: rwbarton, carter GHC Trac Issues: #15780, #14251, #15747 Differential Revision: https://phabricator.haskell.org/D5254
* Revert "Add Int8# and Word8#"Ben Gamari2018-10-091-4/+0
| | | | | | | | | This unfortunately broke i386 support since it introduced references to byte-sized registers that don't exist on that architecture. Reverts binary submodule This reverts commit 5d5307f943d7581d7013ffe20af22233273fba06.
* Add Int8# and Word8#Michal Terepeta2018-10-071-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the first step of implementing: https://github.com/ghc-proposals/ghc-proposals/pull/74 The main highlights/changes: - `primops.txt.pp` gets two new sections for two new primitive types for signed and unsigned 8-bit integers (`Int8#` and `Word8` respectively) along with basic arithmetic and comparison operations. `PrimRep`/`RuntimeRep` get two new constructors for them. All of the primops translate into the existing `MachOP`s. - For `CmmCall`s the codegen will now zero-extend the values at call site (so that they can be moved to the right register) and then truncate them back their original width. - x86 native codegen needed some updates, since it wasn't able to deal with the new widths, but all the changes are quite localized. LLVM backend seems to just work. Bumps binary submodule. Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com> Test Plan: ./validate with new tests Reviewers: hvr, goldfire, bgamari, simonmar Subscribers: Abhiroop, dfeuer, rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4475
* Multiple fixes / improvements for LLVM backendKavon Farvardin2018-10-041-49/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | - Fix for #13904 -- stop "trashing" callee-saved registers, since it is not actually doing anything useful. - Fix for #14251 -- fixes the calling convention for functions passing raw SSE-register values by adding padding as needed to get the values in the right registers. This problem cropped up when some args were unused an dropped from the live list. - Fixed a typo in 'readnone' attribute - Added 'lower-expect' pass to level 0 LLVM optimization passes to improve block layout in LLVM for stack checks, etc. Test Plan: `make test WAYS=optllvm` and `make test WAYS=llvm` Reviewers: bgamari, simonmar, angerman Reviewed By: angerman Subscribers: rwbarton, carter GHC Trac Issues: #13904, #14251 Differential Revision: https://phabricator.haskell.org/D5190
* Fix precision of asinh/acosh/atanh by making them primopsArtem Pelenitsyn2018-08-211-0/+8
| | | | | | | | | | Reviewers: hvr, bgamari, simonmar, jrtc27 Reviewed By: bgamari Subscribers: alpmestan, rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D5034
* Turn on MonadFail desugaring by defaultHerbert Valerio Riedel2018-08-071-9/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This contains two commits: ---- Make GHC's code-base compatible w/ `MonadFail` There were a couple of use-sites which implicitly used pattern-matches in `do`-notation even though the underlying `Monad` didn't explicitly support `fail` This refactoring turns those use-sites into explicit case discrimations and adds an `MonadFail` instance for `UniqSM` (`UniqSM` was the worst offender so this has been postponed for a follow-up refactoring) --- Turn on MonadFail desugaring by default This finally implements the phase scheduled for GHC 8.6 according to https://prime.haskell.org/wiki/Libraries/Proposals/MonadFail#Transitionalstrategy This also preserves some tests that assumed MonadFail desugaring to be active; all ghc boot libs were already made compatible with this `MonadFail` long ago, so no changes were needed there. Test Plan: Locally performed ./validate --fast Reviewers: bgamari, simonmar, jrtc27, RyanGlScott Reviewed By: bgamari Subscribers: bgamari, RyanGlScott, rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D5028
* Fix typosKrzysztof Gogolewski2018-08-051-2/+2
|
* Fix a major copy'n'paste error in LLVM CodeGenKrzysztof Gogolewski2018-07-221-1/+1
| | | | | | | | | | | | | | | | Summary: In D4592, `AddWordC` is lowered as an unsigned subtraction instead of an unsigned addition when compiling with LLVM. This patch rectifies that. Reviewers: angerman, bgamari, monoidal Reviewed By: angerman, bgamari, monoidal Subscribers: osa1, rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4969
* Allow CmmLabelDiffOff with different widthsSimon Marlow2018-05-161-5/+9
| | | | | | | | | | | | | | | | | | Summary: This change makes it possible to generate a static 32-bit relative label offset on x86_64. Currently we can only generate word-sized label offsets. This will be used in D4634 to shrink info tables. See D4632 for more details. Test Plan: See D4632 Reviewers: bgamari, niteria, michalt, erikd, jrtc27, osa1 Subscribers: thomie, carter Differential Revision: https://phabricator.haskell.org/D4633
* Add 'addWordC#' PrimOpSebastian Graf2018-05-051-0/+6
| | | | | | | | | | | | | | | | | | | This is mostly for congruence with 'subWordC#' and '{add,sub}IntC#'. I found 'plusWord2#' while implementing this, which both lacks documentation and has a slightly different specification than 'addWordC#', which means the generic implementation is unnecessarily complex. While I was at it, I also added lacking meta-information on PrimOps and refactored 'subWordC#'s generic implementation to be branchless. Reviewers: bgamari, simonmar, jrtc27, dfeuer Reviewed By: bgamari, dfeuer Subscribers: dfeuer, thomie, carter Differential Revision: https://phabricator.haskell.org/D4592
* Add new mbmi and mbmi2 compiler flagsJohn Ky2018-01-211-20/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | This adds support for the bit deposit and extraction operations provided by the BMI and BMI2 instruction set extensions on modern amd64 machines. Implement x86 code generator for pdep and pext. Properly initialise bmiVersion field. pdep and pext test cases Fix pattern match for pdep and pext instructions Fix build of pdep and pext code for 32-bit architectures Test Plan: Validate Reviewers: austin, simonmar, bgamari, angerman Reviewed By: bgamari Subscribers: trommler, carter, angerman, thomie, rwbarton, newhoggy GHC Trac Issues: #14206 Differential Revision: https://phabricator.haskell.org/D4236
* Revert "Add new mbmi and mbmi2 compiler flags"Ben Gamari2017-11-221-6/+0
| | | | | | This broke the 32-bit build. This reverts commit f5dc8ccc29429d0a1d011f62b6b430f6ae50290c.
* Add new mbmi and mbmi2 compiler flagsJohn Ky2017-11-151-0/+6
| | | | | | | | | | | | | | | | | This adds support for the bit deposit and extraction operations provided by the BMI and BMI2 instruction set extensions on modern amd64 machines. Test Plan: Validate Reviewers: austin, simonmar, bgamari, hvr, goldfire, erikd Reviewed By: bgamari Subscribers: goldfire, erikd, trommler, newhoggy, rwbarton, thomie GHC Trac Issues: #14206 Differential Revision: https://phabricator.haskell.org/D4063
* Turn `compareByteArrays#` out-of-line primop into inline primopalexbiehl2017-10-291-0/+1
| | | | | | | | | | | | Depends on D4090 Reviewers: austin, bgamari, erikd, simonmar, alexbiehl Reviewed By: bgamari Subscribers: rwbarton, thomie Differential Revision: https://phabricator.haskell.org/D4091
* Add -falignment-sanitization flagBen Gamari2017-10-291-0/+4
| | | | | | | | | | | | | | | | | | | Here we add a flag to instruct the native code generator to add alignment checks in all info table dereferences. This is helpful in catching pointer tagging issues. Thanks to @jrtc27 for uncovering the tagging issues on Sparc which inspired this flag. Test Plan: Validate Reviewers: simonmar, austin, erikd Reviewed By: simonmar Subscribers: rwbarton, trofi, thomie, jrtc27 Differential Revision: https://phabricator.haskell.org/D4101
* compiler: introduce custom "GhcPrelude" PreludeHerbert Valerio Riedel2017-09-191-0/+2
| | | | | | | | | | | | | | | | | | This switches the compiler/ component to get compiled with -XNoImplicitPrelude and a `import GhcPrelude` is inserted in all modules. This is motivated by the upcoming "Prelude" re-export of `Semigroup((<>))` which would cause lots of name clashes in every modulewhich imports also `Outputable` Reviewers: austin, goldfire, bgamari, alanz, simonmar Reviewed By: bgamari Subscribers: goldfire, rwbarton, thomie, mpickering, bgamari Differential Revision: https://phabricator.haskell.org/D3989
* Canonicalise Monoid instances in GHCHerbert Valerio Riedel2017-09-091-2/+1
| | | | IOW, code compiles -Wnoncanonical-monoid-instances clean now
* Drop GHC 7.10 compatibilityRyan Scott2017-08-011-4/+0
| | | | | | | | | | | | | | | | GHC 8.2.1 is out, so now GHC's support window only extends back to GHC 8.0. This means we can delete gobs of code that was only used for GHC 7.10 support. Hooray! Test Plan: ./validate Reviewers: hvr, bgamari, austin, goldfire, simonmar Reviewed By: bgamari Subscribers: Phyx, rwbarton, thomie Differential Revision: https://phabricator.haskell.org/D3781
* Hoopl: remove dependency on Hoopl packageMichal Terepeta2017-06-231-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* Typos [ci skip]Gabor Greif2017-06-131-1/+1
|
* Prefer #if defined to #ifdefBen Gamari2017-04-281-1/+1
| | | | Our new CPP linter enforces this.
* Typos in comments [ci skip]Gabor Greif2017-04-051-1/+1
|
* Generate better fp abs for X86 and llvm with default cmm otherwiseDominic Steinitz2017-03-071-0/+2
| | | | | | | | | | | | | | | | | | | | | | | Currently we have this in libraries/base/GHC/Float.hs: ``` abs x | x == 0 = 0 -- handles (-0.0) | x > 0 = x | otherwise = negateFloat x ``` But 3-4 years ago it was noted that this was inefficient: https://mail.haskell.org/pipermail/libraries/2013-April/019690.html We can generate better code for X86 and llvm and for others generate some custom cmm code which is similar to what the compiler generates now. Reviewers: austin, simonmar, hvr, bgamari Reviewed By: bgamari Subscribers: dfeuer, thomie Differential Revision: https://phabricator.haskell.org/D3265
* Fix LLVM TBAA metadataDemi Obenour2016-12-091-4/+2
| | | | | | | | | | | | | | | | | | | | | | Accesses through a Cmm local are currently reported as having the "other" type, which can only alias other "other" accesses. However, this assumption is incorrect, which can result in silent bad LLVM codegen. Fixes #9308. Fixes #9504. Test Plan: GHC CI Reviewers: rwbarton, austin, bgamari Reviewed By: bgamari Subscribers: michalt, thomie Differential Revision: https://phabricator.haskell.org/D2758 GHC Trac Issues: #9125, #9308, #9504
* LLVM generate llvm.expect for conditional branchesAlex Biehl2016-11-171-7/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds likeliness annotations to heap and and stack checks and modifies the llvm codegen to recognize those to help it generate better code. So with this patch ``` ... if ((Sp + 8) - 24 < SpLim) (likely: False) goto c23c; else goto c23d; ... ``` roughly generates: ``` %ln23k = icmp ult i64 %ln23j, %SpLim_Arg %ln23m = call ccc i1 (i1, i1) @llvm.expect.i1( i1 %ln23k, i1 0 ) br i1 %ln23m, label %c23c, label %c23d ``` Note the call to `llvm.expect` which denotes the expected result for the comparison. Test Plan: Look at assembler code with and without this patch. If the heap-checks moved out of the way we are happy. Reviewers: austin, simonmar, bgamari Reviewed By: bgamari Subscribers: michalt, thomie Differential Revision: https://phabricator.haskell.org/D2688 GHC Trac Issues: #8321
* Add MonadUnique instance for LlvmMBen Gamari2016-03-111-2/+2
| | | | | | | | | | Reviewers: erikd, austin Reviewed By: erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1994
* Typos in commentsGabor Greif2016-01-271-1/+1
|
* Drop pre-AMP compatibility CPP conditionalsHerbert Valerio Riedel2015-12-311-4/+0
| | | | | | | | | | | | Since GHC 8.1/8.2 only needs to be bootstrap-able by GHC 7.10 and GHC 8.0 (and GHC 8.2), we can now finally drop all that pre-AMP compatibility CPP-mess for good! Reviewers: austin, goldfire, bgamari Subscribers: goldfire, thomie, erikd Differential Revision: https://phabricator.haskell.org/D1724
* Make HasDynFlags more transformers friendlyHerbert Valerio Riedel2015-12-081-5/+5
| | | | | | | | | | | | | | | | | Ideally, we'd have the more general instance (MonadTrans t, Monad m, HasDynFlags m) => HasDynFlags (t m) where getDynFlags = lift getDynFlags definition. However, that one would overlap with the `HasDynFlags (GhcT m)` instance. Instead we define instances for a couple of common Monad transformers explicitly in order to avoid nasty overlapping instances. This is a preparatory refactoring for #10874 Reviewed By: austin Differential Revision: https://phabricator.haskell.org/D1581
View Lorry Controller Status