- May 22, 2020
-
-
-
-
The immediate goal is let the hie-bios.bat script set CABFLAGS with `-v0` and remove all cabal output except the compiler arguments
-
It is a direct translation of the sh script
-
- May 21, 2020
-
-
It doesn't belong into GHC.Unit.State
-
Previously, we sorted according to the test name and way, but the metrics (max_bytes_used/peak_megabytes_allocated etc.) were appearing in nondeterministic order.
-
The testcase works now. See explanation in ghc/ghc#11506 (comment 273202)
-
We changed to use variable length encodings for many types by default, including Word32. This makes sense for numbers but not when Word32 is meant to represent four bytes. I added a FixedLengthEncoding newtype to Binary who's instances interpret their argument as a collection of bytes instead of a number. We then use this when writing/reading magic numbers to the iface file. I also took the libery to remove the dummy iface field. This fixes #18180.
-
* Besides resizing functions, shrinking ones also mutate the size of a mutable array and because of those two `sizeofMutabeByteArray` and `sizeofSmallMutableArray` are now deprecated * Change reference in documentation to the newer functions `getSizeof*` instead of `sizeof*` for shrinking functions * Fix incorrect mention of "byte" instead of "small"
-
-
They used to be strict until 4d2ac2d4 (9 years ago). It's obviously better to be strict for performance reasons. It also blocks #18067. NoFib results: ``` -------------------------------------------------------------------------------- Program Allocs Instrs -------------------------------------------------------------------------------- integer -1.1% +0.4% wheel-sieve2 +21.2% +20.7% -------------------------------------------------------------------------------- Min -1.1% -0.0% Max +21.2% +20.7% Geometric Mean +0.2% +0.2% ``` The regression in `wheel-sieve2` is due to reboxing that likely will go away with the resolution of #18067. See !3282 for details. Fixes #18187.
-
-
-
If we are on a 64 bit platform, we can use the efficient Enum Word methods for the Enum Word64 instance.
-
The INLINABLE pragmas ensure that we export stable (unoptimised) unfoldings in the interface file so we can do list fusion at usage sites. Related tickets: #15185, #8763, #18178.
-
-
-
In GHC, not in the code being compiled!
-
-
-
-
-
-
This patch adds the fixes that allow for file names containing spaces to be passed to GHCi's ':script' command to the release notes for 8.12 and expands the user-guide documentation for ':script' by mentioning how such file names can be passed. Related to #18027.
-
This patch updates the user interface of GHCi so that file names passed to the ':script' command can be wrapped in double quotes. For example: :script "foo bar.script" The implementation uses a modified version of 'words' that treats character sequences enclosed in double quotes as single words. Fixes #18027.
-
The syntax for GHCi's ":script" command allows for only a single file name to be passed as an argument. This patch adds a test for the cases in which a file name is missing or multiple file names are passed. Related to #T18027.
-
This patch updates the user interface of GHCi so that file names passed to the ':script' command may contain spaces escaped with a backslash. For example: :script foo\ bar.script The implementation uses a modified version of 'words' that does not break on escaped spaces. Fixes #18027.
-
-
In #18053 we ended up with a suboptimal code layout because the code layout algorithm didn't distinguish between conditional and unconditional control flow. We can completely eliminate unconditional control flow instructions by placing blocks next to each other, not so much for conditionals. In terms of implementation we simply give conditional branches less weight before computing the layout. Fixes #18053
-
When assigning registers we now first try registers we assigned to in the past, instead of picking the "first" one. This is in extremely helpful when dealing with loops for which variables are dead for part of the loop. This is important for patterns like this: foo = arg1 loop: use(foo) ... foo = getVal() goto loop; There we: * assign foo to the register of arg1. * use foo, it's dead after this use as it's overwritten after. * do other things. * look for a register to put foo in. If we pick an arbitrary one it might differ from the register the start of the loop expect's foo to be in. To fix this we simply look for past register assignments for the given variable. If we find one and the register is free we use that register. This reduces the need for fixup blocks which match the register assignment between blocks. In the example above between the end and the head of the loop. This patch also moves branch weight estimation ahead of register allocation and adds a flag to control it (cmm-static-pred). * It means the linear allocator is more likely to assign the hotter code paths first. * If it assign these first we are: + Less likely to spill on the hot path. + Less likely to introduce fixup blocks on the hot path. These two measure combined are surprisingly effective. Based on nofib we get in the mean: * -0.9% instructions executed * -0.1% reads/writes * -0.2% code size. * -0.1% compiler allocations. * -0.9% compile time. * -0.8% runtime. Most of the benefits are simply a result of removing redundant moves and spills. Reduced compiler allocations likely are the result of less code being generated. (The added lookup is mostly non-allocating). -
-
It is rather confusing that when lint finds an error in a rule attached to a binder, it reports the error as in the RHS, not the rule: ... In the RHS of foo We add a clarifying line: ... In the RHS of foo In a rule attached to foo The implication that the rule lives inside the RHS is a bit odd, but this niggle is already present for unfoldings, whose pattern we are following.
-
Implementation for Ticket #16393. Explicit specificity allows users to manually create inferred type variables, by marking them with braces. This way, the user determines which variables can be instantiated through visible type application. The additional syntax is included in the parser, allowing users to write braces in type variable binders (type signatures, data constructors etc). This information is passed along through the renamer and verified in the type checker. The AST for type variable binders, data constructors, pattern synonyms, partial signatures and Template Haskell has been updated to include the specificity of type variables. Minor notes: - Bumps haddock submodule - Disables pattern match checking in GHC.Iface.Type with GHC 8.8
-
* GHC.Fingerprint.Types: Fingerprint * GHC.RTS.Flags: GiveGCStats, GCFlags, ConcFlags, DebugFlags, CCFlags, DoHeapProfile, ProfFlags, DoTrace, TraceFlags, TickyFlags, ParFlags and RTSFlags * GHC.Stats: RTSStats and GCStats * GHC.ByteOrder: ByteOrder * GHC.Unicode: GeneralCategory * GHC.Stack.Types: SrcLoc Metric Increase: haddock.base
-
- May 17, 2020
-
-
Ryan Scott authored
There are two different Notes named `[When to print foralls]`. The most up-to-date one is in `GHC.Iface.Type`, but there is a second one in `GHC.Core.TyCo.Ppr`. The latter is less up-to-date, as it was written before GHC switched over to using ifaces to pretty-print types. I decided to just remove the latter and replace it with a reference to the former. [ci skip]
-
- May 15, 2020
-
-
This MachOp was introduced by 2c959a18 but a wildcard match in cmmMachOpFoldM hid the fact that it wasn't handled. Ideally we would eliminate the match but this appears to be a larger task. Fixes #18141.
-
This patch does two things: Fix possible unsoundness in what was called the "IO hack" and implement part 2.1 of the "fixing precise exceptions" plan in https://gitlab.haskell.org/ghc/ghc/wikis/fixing-precise-exceptions, which, in combination with !2956, supersedes !3014 and !2525. **IO hack** The "IO hack" (which is a fallback to preserve precise exceptions semantics and thus soundness, rather than some smart thing that increases precision) is called `exprMayThrowPreciseException` now. I came up with two testcases exemplifying possible unsoundness (if twisted enough) in the old approach: - `T13380d`: Demonstrating unsoundness of the "IO hack" when resorting to manual state token threading and direct use of primops. More details below. - `T13380e`: Demonstrating unsoundness of the "IO hack" when we have Nested CPR. Not currently relevant, as we don't have Nested CPR yet. - `T13380f`: Demonstrating unsoundness of the "IO hack" for safe FFI calls. Basically, the IO hack assumed that precise exceptions can only be thrown from a case scrutinee of type `(# State# RealWorld, _ #)`. I couldn't come up with a program using the `IO` abstraction that violates this assumption. But it's easy to do so via manual state token threading and direct use of primops, see `T13380d`. Also similar code might be generated by Nested CPR in the (hopefully not too) distant future, see `T13380e`. Hence, we now have a more careful test in `forcesRealWorld` that passes `T13380{d,e}` (and will hopefully be robust to Nested CPR). **Precise exceptions** In #13380 and #17676 we saw that we didn't preserve precise exception semantics in demand analysis. We fixed that with minimal changes in !2956, but that was terribly unprincipled. That unprincipledness resulted in a loss of precision, which is tracked by these new test cases: - `T13380b`: Regression in dead code elimination, because !2956 was too syntactic about `raiseIO#` - `T13380c`: No need to apply the "IO hack" when the IO action may not throw a precise exception (and the existing IO hack doesn't detect that) Fixing both issues in !3014 turned out to be too complicated and had the potential to regress in the future. Hence we decided to only fix `T13380b` and augment the `Divergence` lattice with a new middle-layer element, `ExnOrDiv`, which means either `Diverges` (, throws an imprecise exception) or throws a *precise* exception. See the wiki page on Step 2.1 for more implementational details: https://gitlab.haskell.org/ghc/ghc/wikis/fixing-precise-exceptions#dead-code-elimination-for-raiseio-with-isdeadenddiv-introducing-exnordiv-step-21
-
- May 14, 2020
-
-
Ben Gamari authored
-
Data.IntMap gained a dedicated `disjoint` function in containers-0.6.2.1. This patch applies this function where appropriate in hopes of modest compiler performance improvements. Closes #16806.
-
* Replace some non-deterministic lazy folds with strict folds. * Replace some O(n log n) folds in deterministic order with O(n) non-deterministic folds. * Replace some folds with set-operations on the underlying IntMaps. This reduces max residency when compiling `nofib/spectral/simple/Main.hs` with -O0 by about 1%. Maximum residency when compiling Cabal also seems reduced on the order of 3-9%.
-
