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| author | klebinger.andreas@gmx.at <klebinger.andreas@gmx.at> | 2019-04-02 14:20:12 +0200 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-04-03 00:34:57 -0400 |
| commit | 5a75ccd0993ff2fdf827824e28ae7db4ad9c25ad (patch) | |
| tree | efae16bdc9be651f85148a6ef68fc38d2664215b | |
| parent | bf73419518ca550e85188616f860961c7e2a336b (diff) | |
| download | haskell-5a75ccd0993ff2fdf827824e28ae7db4ad9c25ad.tar.gz | |
Fix faulty substitutions in StgCse (#11532).
`substBndr` should rename bindings which shadow existing ids.
However while it was renaming the bindings it was not adding proper substitutions
for renamed bindings.
Instead of adding a substitution of the form `old -> new` for renamed
bindings it mistakenly added `old -> old` if no replacement had taken
place while adding none if `old` had been renamed.
As a byproduct this should improve performance, as we no longer add
useless substitutions for unshadowed bindings.
| -rw-r--r-- | compiler/simplStg/StgCse.hs | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/compiler/simplStg/StgCse.hs b/compiler/simplStg/StgCse.hs index 386515ee27..269738e488 100644 --- a/compiler/simplStg/StgCse.hs +++ b/compiler/simplStg/StgCse.hs @@ -245,8 +245,8 @@ substBndr env old_id new_id = uniqAway (ce_in_scope env) old_id no_change = new_id == old_id env' = env { ce_in_scope = ce_in_scope env `extendInScopeSet` new_id } - new_env | no_change = env' { ce_subst = extendVarEnv (ce_subst env) old_id new_id } - | otherwise = env' + new_env | no_change = env' + | otherwise = env' { ce_subst = extendVarEnv (ce_subst env) old_id new_id } substBndrs :: CseEnv -> [InVar] -> (CseEnv, [OutVar]) substBndrs env bndrs = mapAccumL substBndr env bndrs |