From ccd5aec2104ec4f904f97d948f2dcd9dcea03eef Mon Sep 17 00:00:00 2001 From: Simon Marlow Date: Thu, 25 Mar 2010 11:48:47 +0000 Subject: [PATCH] Never jump directly to a thunk's entry code, even if it is single-entry I don't think this fixes any bugs as we don't have single-entry thunks at the moment, but it could cause problems for parallel execution if we ever did re-introduce update avoidance. --- compiler/codeGen/ClosureInfo.lhs | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) diff --git a/compiler/codeGen/ClosureInfo.lhs b/compiler/codeGen/ClosureInfo.lhs index 18734e1..d2c63b3 100644 --- a/compiler/codeGen/ClosureInfo.lhs +++ b/compiler/codeGen/ClosureInfo.lhs @@ -604,19 +604,14 @@ getCallMethod _ _ _ (LFCon con) n_args = ASSERT( n_args == 0 ) ReturnCon con -getCallMethod dflags name caf (LFThunk _ _ updatable std_form_info is_fun) n_args +getCallMethod _dflags _name _caf (LFThunk _ _ _updatable _std_form_info is_fun) _n_args | is_fun -- it *might* be a function, so we must "call" it (which is -- always safe) = SlowCall -- We cannot just enter it [in eval/apply, the entry code -- is the fast-entry code] -- Since is_fun is False, we are *definitely* looking at a data value - | updatable || doingTickyProfiling dflags -- to catch double entry - {- OLD: || opt_SMP - I decided to remove this, because in SMP mode it doesn't matter - if we enter the same thunk multiple times, so the optimisation - of jumping directly to the entry code is still valid. --SDM - -} + | otherwise = EnterIt -- We used to have ASSERT( n_args == 0 ), but actually it is -- possible for the optimiser to generate @@ -625,9 +620,16 @@ getCallMethod dflags name caf (LFThunk _ _ updatable std_form_info is_fun) n_arg -- This happens as a result of the case-of-error transformation -- So the right thing to do is just to enter the thing - | otherwise -- Jump direct to code for single-entry thunks - = ASSERT( n_args == 0 ) - JumpToIt (thunkEntryLabel name caf std_form_info updatable) +-- Old version: +-- | updatable || doingTickyProfiling dflags -- to catch double entry +-- = EnterIt +-- | otherwise -- Jump direct to code for single-entry thunks +-- = JumpToIt (thunkEntryLabel name caf std_form_info updatable) +-- +-- Now we never use JumpToIt, even if the thunk is single-entry, since +-- the thunk may have already been entered and blackholed by another +-- processor. + getCallMethod _ _ _ (LFUnknown True) _ = SlowCall -- Might be a function @@ -946,6 +948,7 @@ closureLabelFromCI _ _ = panic "closureLabelFromCI" -- thunkEntryLabel is a local help function, not exported. It's used from both -- entryLabelFromCI and getCallMethod. +{- UNUSED: thunkEntryLabel :: Name -> CafInfo -> StandardFormInfo -> Bool -> CLabel thunkEntryLabel _thunk_id _ (ApThunk arity) is_updatable = enterApLabel is_updatable arity @@ -953,16 +956,21 @@ thunkEntryLabel _thunk_id _ (SelectorThunk offset) upd_flag = enterSelectorLabel upd_flag offset thunkEntryLabel thunk_id caf _ _is_updatable = enterIdLabel thunk_id caf +-} +{- UNUSED: enterApLabel :: Bool -> Int -> CLabel enterApLabel is_updatable arity | tablesNextToCode = mkApInfoTableLabel is_updatable arity | otherwise = mkApEntryLabel is_updatable arity +-} +{- UNUSED: enterSelectorLabel :: Bool -> Int -> CLabel enterSelectorLabel upd_flag offset | tablesNextToCode = mkSelectorInfoLabel upd_flag offset | otherwise = mkSelectorEntryLabel upd_flag offset +-} enterIdLabel :: Name -> CafInfo -> CLabel enterIdLabel id -- 1.7.10.4