diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/coreSyn/CoreLint.hs | 28 | ||||
| -rw-r--r-- | compiler/main/StaticPtrTable.hs | 2 | ||||
| -rw-r--r-- | compiler/main/TidyPgm.hs | 7 | ||||
| -rw-r--r-- | compiler/simplCore/SimplCore.hs | 62 |
4 files changed, 66 insertions, 33 deletions
diff --git a/compiler/coreSyn/CoreLint.hs b/compiler/coreSyn/CoreLint.hs index b3cec5f22a..2a2284b09d 100644 --- a/compiler/coreSyn/CoreLint.hs +++ b/compiler/coreSyn/CoreLint.hs @@ -1636,18 +1636,32 @@ top-level ones. See Note [Exported LocalIds] and Trac #9857. Note [Checking StaticPtrs] ~~~~~~~~~~~~~~~~~~~~~~~~~~ +See SimplCore Note [Grand plan for static forms] for an overview. -Every occurrence of the data constructor @StaticPtr@ should be moved to the top -level by the FloatOut pass. The linter is checking that no occurrence is left -nested within an expression. +Every occurrence of the data constructor @StaticPtr@ should be moved +to the top level by the FloatOut pass. It's vital that we don't have +nested StaticPtr uses after CorePrep, because we populate the Static +Pointer Table from the top-level bindings. See SimplCore Note [Grand +plan for static forms]. -The check is enabled only if the module uses the StaticPointers language -extension. This optimization arose from the need to compile "GHC.StaticPtr", -which otherwise would be rejected because the following binding +The linter checks that no occurrence is left behind, nested within an +expression. The check is enabled only: + +* After the FloatOut, CorePrep, and CoreTidy passes. + We could check more often, but the condition doesn't hold until + after the first FloatOut pass. + +* When the module uses the StaticPointers language extension. This is + a little hack. This optimization arose from the need to compile + GHC.StaticPtr, which otherwise would be rejected because of the + following binding for the StaticPtr data constructor itself: StaticPtr = \a b1 b2 b3 b4 -> StaticPtr a b1 b2 b3 b4 -contains an application of `StaticPtr` nested within the lambda abstractions. + which contains an application of `StaticPtr` nested within the + lambda abstractions. This binding is injected by CorePrep. + + Note that GHC.StaticPtr is itself compiled without -XStaticPointers. Note [Type substitution] ~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/compiler/main/StaticPtrTable.hs b/compiler/main/StaticPtrTable.hs index c13bcd8d3a..9ec970f453 100644 --- a/compiler/main/StaticPtrTable.hs +++ b/compiler/main/StaticPtrTable.hs @@ -48,6 +48,8 @@ {-# LANGUAGE ViewPatterns #-} module StaticPtrTable (sptModuleInitCode) where +-- See SimplCore Note [Grand plan for static forms] + import CLabel import CoreSyn import DataCon diff --git a/compiler/main/TidyPgm.hs b/compiler/main/TidyPgm.hs index 945e3f86e7..401f939d44 100644 --- a/compiler/main/TidyPgm.hs +++ b/compiler/main/TidyPgm.hs @@ -375,7 +375,10 @@ tidyProgram hsc_env (ModGuts { mg_module = mod -- See Note [Injecting implicit bindings] ; all_tidy_binds = implicit_binds ++ tidy_binds - -- get the TyCons to generate code for. Careful! We must use + -- See SimplCore Note [Grand plan for static forms] + ; spt_init_code = sptModuleInitCode mod all_tidy_binds + + -- Get the TyCons to generate code for. Careful! We must use -- the untidied TypeEnv here, because we need -- (a) implicit TyCons arising from types and classes defined -- in this module @@ -409,7 +412,7 @@ tidyProgram hsc_env (ModGuts { mg_module = mod cg_tycons = alg_tycons, cg_binds = all_tidy_binds, cg_foreign = foreign_stubs `appendStubC` - sptModuleInitCode mod all_tidy_binds, + spt_init_code, cg_dep_pkgs = map fst $ dep_pkgs deps, cg_hpc_info = hpc_info, cg_modBreaks = modBreaks }, diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs index 654fd521bd..86eadc7a37 100644 --- a/compiler/simplCore/SimplCore.hs +++ b/compiler/simplCore/SimplCore.hs @@ -990,27 +990,41 @@ transferIdInfo exported_id local_id -- rules as we transfer them from one function to another --- Note [Grand plan for static forms] --- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --- --- Static forms go through the compilation phases as follows: --- --- The renamer looks for out-of-scope names in the body of the static form. --- If all names are in scope, the free variables of the body are stored in AST --- at the location of the static form. --- --- The typechecker verifies that all free variables occurring in the static form --- are closed (see Note [Bindings with closed types] in TcRnTypes). --- --- The desugarer replaces the static form with an application of the data --- constructor 'StaticPtr' (defined in module GHC.StaticPtr of base). --- --- The simplifier runs the FloatOut pass which moves the applications of --- 'StaticPtr' to the top level. Thus the FloatOut pass is always executed, --- event when optimizations are disabled. --- --- The CoreTidy pass produces a C function which inserts all the floated --- 'StaticPtr' in the static pointer table (See StaticPtrTable.hs). --- This pass also exports the Ids of floated 'StaticPtr's so they can be linked --- with the C function. --- +{- Note [Grand plan for static forms] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Static forms go through the compilation phases as follows. +Here is a running example: + + f x = let k = map toUpper + in ...(static k)... + +* The renamer looks for out-of-scope names in the body of the static + form, as always If all names are in scope, the free variables of the + body are stored in AST at the location of the static form. + +* The typechecker verifies that all free variables occurring in the + static form are closed (see Note [Bindings with closed types] in + TcRnTypes). In our example, 'k' is closed, even though it is bound + in a nested let, we are fine. + +* The desugarer replaces the static form with an application of the + data constructor 'StaticPtr' (defined in module GHC.StaticPtr of + base). So we get + + f x = let k = map toUpper + in ...(StaticPtr <fingerprint> k)... + +* The simplifier runs the FloatOut pass which moves the applications + of 'StaticPtr' to the top level. Thus the FloatOut pass is always + executed, even when optimizations are disabled. So we get + + k = map toUpper + lvl = StaticPtr <fingerprint> k + f x = ...lvl... + +* The CoreTidy pass produces a C function which inserts all the + floated 'StaticPtr' in the static pointer table (see the call to + StaticPtrTable.sptModuleInitCode in TidyPgm). CoreTidy pass also + exports the Ids of floated 'StaticPtr's so they can be linked with + the C function. +-} |