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| author | Austin Seipp <aseipp@pobox.com> | 2013-08-10 22:39:15 -0500 |
|---|---|---|
| committer | Austin Seipp <aseipp@pobox.com> | 2013-08-10 23:12:27 -0500 |
| commit | e2b72cadce3ae799a74981f9957b40bb201f1ba1 (patch) | |
| tree | bba6e9247351c4ef646a758422458946132f0c28 | |
| parent | 94be58893b084af0dc1a65b0faaa453a23fe6750 (diff) | |
| download | haskell-e2b72cadce3ae799a74981f9957b40bb201f1ba1.tar.gz | |
Mark retry# as returning bottom.
This change helps the simplifier eliminate unreachable code, since
retry# technically doesn't return.
This closes ticket #8091.
Authored-by: Patrick Palka <patrick@parcs.ath.cx>
Signed-off-by: Austin Seipp <aseipp@pobox.com>
| -rw-r--r-- | compiler/prelude/primops.txt.pp | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/compiler/prelude/primops.txt.pp b/compiler/prelude/primops.txt.pp index 3d3518b095..0c325a6259 100644 --- a/compiler/prelude/primops.txt.pp +++ b/compiler/prelude/primops.txt.pp @@ -1611,9 +1611,24 @@ primop AtomicallyOp "atomically#" GenPrimOp out_of_line = True has_side_effects = True +-- NB: retry#'s strictness information specifies it to return bottom. +-- This lets the compiler perform some extra simplifications, since retry# +-- will technically never return. +-- +-- This allows the simplifier to replace things like: +-- +-- case retry# s1 +-- (# s2, a #) -> e +-- +-- with: +-- +-- retry# s1 +-- +-- where 'e' would be unreachable anyway. primop RetryOp "retry#" GenPrimOp State# RealWorld -> (# State# RealWorld, a #) with + strictness = { \ _arity -> mkStrictSig (mkTopDmdType [topDmd] botRes) } out_of_line = True has_side_effects = True |