From 5ff0a171aa199f34054092e728b56ddf6d58a093 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Fri, 21 Jun 2019 11:24:50 -0400
Subject: [PATCH] CoreToStg: Enable CAFfyness checking with -dstg-lint
The debugging involved in finding #16846 wouldn't have been necessary
had the consistentCafInfo check been enabled. However, :wq
---
compiler/stgSyn/CoreToStg.hs | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/compiler/stgSyn/CoreToStg.hs b/compiler/stgSyn/CoreToStg.hs
index 6717ad9587a..caa012124b4 100644
--- a/compiler/stgSyn/CoreToStg.hs
+++ b/compiler/stgSyn/CoreToStg.hs
@@ -268,7 +268,7 @@ coreTopBindToStg dflags this_mod env ccs (NonRec id rhs)
bind = StgTopLifted $ StgNonRec id stg_rhs
in
- ASSERT2(consistentCafInfo id bind, ppr id )
+ assertConsistentCaInfo dflags id bind (ppr bind)
-- NB: previously the assertion printed 'rhs' and 'bind'
-- as well as 'id', but that led to a black hole
-- where printing the assertion error tripped the
@@ -296,9 +296,18 @@ coreTopBindToStg dflags this_mod env ccs (Rec pairs)
bind = StgTopLifted $ StgRec (zip binders stg_rhss)
in
- ASSERT2(consistentCafInfo (head binders) bind, ppr binders)
+ assertConsistentCaInfo dflags (head binders) bind (ppr binders)
(env', ccs', bind)
+-- | CAF consistency issues will generally result in segfaults and are quite
+-- difficult to debug (see #16846). We enable checking of the
+-- 'consistentCafInfo' invariant with @-dstg-lint@ to increase the chance that
+-- we catch these issues.
+assertConsistentCaInfo :: DynFlags -> Id -> StgTopBinding -> SDoc -> a -> a
+assertConsistentCaInfo dflags id bind err_doc result
+ | gopt Opt_DoStgLinting dflags || debugIsOn
+ , not $ consistentCafInfo id bind = pprPanic "assertConsistentCaInfo" err_doc
+ | otherwise = result
-- Assertion helper: this checks that the CafInfo on the Id matches
-- what CoreToStg has figured out about the binding's SRT. The
--
GitLab