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authorBartosz Nitka <niteria@gmail.com>2016-05-12 05:42:21 -0700
committerBartosz Nitka <niteria@gmail.com>2016-05-12 05:42:36 -0700
commit925b0aea8edc1761fcc16feba1601bea38422c92 (patch)
treec2d53491c4fd4b2b3ef8c3b0212bbb195b0fb588 /compiler/stranal
parentda105ca104f8382c33c01050dd04443c9c2d63ea (diff)
downloadhaskell-925b0aea8edc1761fcc16feba1601bea38422c92.tar.gz
Make absentError not depend on uniques
As explained in the comment it will cause changes in inlining if we don't suppress them. Test Plan: ./validate Reviewers: bgamari, austin, simonpj, goldfire, simonmar Reviewed By: simonmar Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2203 GHC Trac Issues: #4012
Diffstat (limited to 'compiler/stranal')
-rw-r--r--compiler/stranal/WwLib.hs9
1 files changed, 8 insertions, 1 deletions
diff --git a/compiler/stranal/WwLib.hs b/compiler/stranal/WwLib.hs
index 4ec36baa5f..d285159a2f 100644
--- a/compiler/stranal/WwLib.hs
+++ b/compiler/stranal/WwLib.hs
@@ -720,7 +720,14 @@ mk_absent_let dflags arg
where
arg_ty = idType arg
abs_rhs = mkRuntimeErrorApp aBSENT_ERROR_ID arg_ty msg
- msg = showSDoc dflags (ppr arg <+> ppr (idType arg))
+ msg = showSDoc (gopt_set dflags Opt_SuppressUniques)
+ (ppr arg <+> ppr (idType arg))
+ -- We need to suppress uniques here because otherwise they'd
+ -- end up in the generated code as strings. This is bad for
+ -- determinism, because with different uniques the strings
+ -- will have different lengths and hence different costs for
+ -- the inliner leading to different inlining.
+ -- See also Note [Unique Determinism] in Unique
mk_seq_case :: Id -> CoreExpr -> CoreExpr
mk_seq_case arg body = Case (Var arg) (sanitiseCaseBndr arg) (exprType body) [(DEFAULT, [], body)]