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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2021-04-16 15:11:43 +0100 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2021-11-23 20:59:53 -0500 |
| commit | b71da5fe871f0236b4033c7cac523fe776a56b29 (patch) | |
| tree | 1c07bb1bcbd639c402bf0e910292e55683441eda /compiler/GHC/Core/Opt/Simplify.hs | |
| parent | 9dcb2ad15df54e209cfae3dd1f51cf8e8d6c69d5 (diff) | |
| download | haskell-wip/T3781.tar.gz | |
Make UnfoldingGuidance account for free variableswip/T3781
For over a decade (#3781) I've wondered whether GHC's
UnfoldingGuidance should take account of free variables. For example:
f x = let g y = case x of ....
in
...(case x of ....g e....)...
If we inline the call to g in the body of the case x, we can save
re-evaluating (and case analysis of) x. This very similar to the
"discounts" we give for arguments. All we need is to do it for
free variables.
It turned out to be rather easy.
* Beef up GHC.Core.Unfold.sizeExpr to accumulate discounts for
free variables.
* Beef up GHC.Core.Unfold.callSiteInline to compute those
discounts, based on info in the InScopeSet
Fixes #3781
Also fixes #19643 (which reminded me of this issue)
Diffstat (limited to 'compiler/GHC/Core/Opt/Simplify.hs')
| -rw-r--r-- | compiler/GHC/Core/Opt/Simplify.hs | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/compiler/GHC/Core/Opt/Simplify.hs b/compiler/GHC/Core/Opt/Simplify.hs index 1398bfd6e7..d046e44a11 100644 --- a/compiler/GHC/Core/Opt/Simplify.hs +++ b/compiler/GHC/Core/Opt/Simplify.hs @@ -2008,7 +2008,7 @@ simplIdF env var cont completeCall :: SimplEnv -> OutId -> SimplCont -> SimplM (SimplFloats, OutExpr) completeCall env var cont - | Just expr <- callSiteInline logger uf_opts case_depth var active_unf + | Just expr <- callSiteInline logger uf_opts in_scope case_depth var active_unf lone_variable arg_infos interesting_cont -- Inline the variable's RHS = do { checkedTick (UnfoldingDone var) @@ -2027,6 +2027,7 @@ completeCall env var cont where uf_opts = seUnfoldingOpts env case_depth = seCaseDepth env + in_scope = seInScope env logger = seLogger env (lone_variable, arg_infos, call_cont) = contArgs cont n_val_args = length arg_infos |