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| author | Björn Gustavsson <[email protected]> | 2018-04-04 15:14:54 +0200 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2018-04-04 15:34:34 +0200 |
| commit | 282fb67730e1bafe722e7149a35e272398f88b34 (patch) | |
| tree | 5e7882c457fc8e480e369b878ab8b43d2f0cf9af /lib/compiler | |
| parent | f99860259ee557851acc865519a315f04d1d4d51 (diff) | |
| download | otp-282fb67730e1bafe722e7149a35e272398f88b34.tar.gz otp-282fb67730e1bafe722e7149a35e272398f88b34.tar.bz2 otp-282fb67730e1bafe722e7149a35e272398f88b34.zip | |
Fix unsafe optimization of record test
beam_record would make an unsafe optimization for the
not_used_p/4 function added to beam_utils_SUITE in this
commit. The bug is in beam_utils, which would falsely
report that {x,4} was unused when it in fact was used.
The bug was in the function not_used/1. The purpose of
not_used/1 is to return a 'not_used' result unless the
actual result is 'used'. Unfortunately it was not
implemented in that way. It would let a 'transparent'
result slip through, which the caller in this case would
convert to 'killed' (because the register was killed on
all other paths).
Reported-by: Richard Carlsson
Diffstat (limited to 'lib/compiler')
| -rw-r--r-- | lib/compiler/src/beam_utils.erl | 5 | ||||
| -rw-r--r-- | lib/compiler/test/beam_utils_SUITE.erl | 24 |
2 files changed, 24 insertions, 5 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl index 047cd5a569..1ddad30328 100644 --- a/lib/compiler/src/beam_utils.erl +++ b/lib/compiler/src/beam_utils.erl @@ -655,9 +655,8 @@ check_liveness_at(R, Lbl, #live{lbl=Ll,res=ResMemorized}=St0) -> {Res,St#live{res=gb_trees:insert(Lbl, Res, St#live.res)}} end. -not_used({exit_not_used,St}) -> {not_used,St}; -not_used({killed,St}) -> {not_used,St}; -not_used({_,_}=Res) -> Res. +not_used({used,_}=Res) -> Res; +not_used({_,St}) -> {not_used,St}. check_liveness_ret(R, R, St) -> {used,St}; check_liveness_ret(_, _, St) -> {killed,St}. diff --git a/lib/compiler/test/beam_utils_SUITE.erl b/lib/compiler/test/beam_utils_SUITE.erl index 7686e69b63..b2a5cada3d 100644 --- a/lib/compiler/test/beam_utils_SUITE.erl +++ b/lib/compiler/test/beam_utils_SUITE.erl @@ -25,7 +25,7 @@ is_not_killed/1,is_not_used_at/1, select/1,y_catch/1,otp_8949_b/1,liveopt/1,coverage/1, y_registers/1,user_predef/1,scan_f/1,cafu/1, - receive_label/1,read_size_file_version/1]). + receive_label/1,read_size_file_version/1,not_used/1]). -export([id/1]). suite() -> [{ct_hooks,[ts_install_cth]}]. @@ -51,7 +51,8 @@ groups() -> user_predef, scan_f, cafu, - read_size_file_version + read_size_file_version, + not_used ]}]. init_per_suite(Config) -> @@ -507,5 +508,24 @@ do_read_size_file_version(E) -> {ok,MaxFiles} end. +-record(s, { a, b }). +-record(k, { v }). + +not_used(_Config) -> + [] = not_used_p(any, #s{b=true}, #k{}, ignored), + #k{v=42} = not_used_p(any, #s{b=false}, #k{v=42}, ignored), + #k{v=42} = not_used_p(any, #s{b=bad}, #k{v=42}, ignored), + ok. + +not_used_p(_C, S, K, L) when is_record(K, k) -> + if ((S#s.b) and + (S#s.b)) -> + []; + true -> + id(L), + id(K#k.v), + id(K) + end. + %% The identity function. id(I) -> I. |