diff options
Diffstat (limited to 'compiler/GHC/Core/Opt/Simplify.hs')
| -rw-r--r-- | compiler/GHC/Core/Opt/Simplify.hs | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/compiler/GHC/Core/Opt/Simplify.hs b/compiler/GHC/Core/Opt/Simplify.hs index d1ca3e3f9c..6c7379faa2 100644 --- a/compiler/GHC/Core/Opt/Simplify.hs +++ b/compiler/GHC/Core/Opt/Simplify.hs @@ -544,14 +544,17 @@ Wrinkles Notice that the stable unfolding moves to the worker! Now demand analysis will work fine on $wf, whereas it has trouble with the original f. c.f. Note [Worker/wrapper for INLINABLE functions] in GHC.Core.Opt.WorkWrap. + This point also applies to strong loopbreakers with INLINE pragmas, see + wrinkle (4). -4. We should /not/ do cast w/w for INLINE functions (hence isInlineUnfolding in - tryCastWorkerWrapper) becuase they'll be inlined, cast and all anyway. And - if we do cast w/w for an INLINE function with arity zero, we get something - really silly: we inline that "worker" right back into the wrapper! Worse than - a no-op, because we haev then lost the stable unfolding. +4. We should /not/ do cast w/w for non-loop-breaker INLINE functions (hence + hasInlineUnfolding in tryCastWorkerWrapper, which responds False to + loop-breakers) because they'll definitely be inlined anyway, cast and + all. And if we do cast w/w for an INLINE function with arity zero, we get + something really silly: we inline that "worker" right back into the wrapper! + Worse than a no-op, because we have then lost the stable unfolding. -Both these wrinkles are exactly like worker/wrapper for strictness analysis: +All these wrinkles are exactly like worker/wrapper for strictness analysis: f is the wrapper and must inline like crazy $wf is the worker and must carry f's original pragma See Note [Worker/wrapper for INLINABLE functions] @@ -600,10 +603,10 @@ tryCastWorkerWrapper env top_lvl old_bndr occ_info bndr (Cast rhs co) | not (isJoinId bndr) -- Not for join points , not (isDFunId bndr) -- nor DFuns; cast w/w is no help, and we can't transform -- a DFunUnfolding in mk_worker_unfolding - , not (exprIsTrivial rhs) -- Not x = y |> co; Wrinkle 1 - , not (isInlineUnfolding unf) -- Not INLINE things: Wrinkle 4 - , not (isUnliftedType rhs_ty) -- Not if rhs has an unlifted type; - -- see Note [Cast w/w: unlifted] + , not (exprIsTrivial rhs) -- Not x = y |> co; Wrinkle 1 + , not (hasInlineUnfolding info) -- Not INLINE things: Wrinkle 4 + , not (isUnliftedType rhs_ty) -- Not if rhs has an unlifted type; + -- see Note [Cast w/w: unlifted] = do { (rhs_floats, work_rhs) <- prepareRhs mode top_lvl occ_fs rhs ; uniq <- getUniqueM ; let work_name = mkSystemVarName uniq occ_fs @@ -637,7 +640,6 @@ tryCastWorkerWrapper env top_lvl old_bndr occ_info bndr (Cast rhs co) occ_fs = getOccFS bndr rhs_ty = coercionLKind co info = idInfo bndr - unf = unfoldingInfo info worker_info = vanillaIdInfo `setDmdSigInfo` dmdSigInfo info `setCprSigInfo` cprSigInfo info @@ -654,8 +656,8 @@ tryCastWorkerWrapper env top_lvl old_bndr occ_info bndr (Cast rhs co) -- Non-stable case: use work_rhs -- Wrinkle 3 of Note [Cast worker/wrapper] mk_worker_unfolding work_id work_rhs - = case unf of - CoreUnfolding { uf_tmpl = unf_rhs, uf_src = src } + = case realUnfoldingInfo info of -- NB: the real one, even for loop-breakers + unf@(CoreUnfolding { uf_tmpl = unf_rhs, uf_src = src }) | isStableSource src -> return (unf { uf_tmpl = mkCast unf_rhs (mkSymCo co) }) _ -> mkLetUnfolding (sm_uf_opts mode) top_lvl InlineRhs work_id work_rhs @@ -895,7 +897,7 @@ completeBind env top_lvl mb_cont old_bndr new_bndr new_rhs | otherwise = assert (isId new_bndr) $ do { let old_info = idInfo old_bndr - old_unf = unfoldingInfo old_info + old_unf = realUnfoldingInfo old_info occ_info = occInfo old_info mode = getMode env |