compiler: Don't apply beam_ssa_type to unreachable functions #7512
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
RobinMorisset
approved these changes
Jul 26, 2023
lib/compiler/src/beam_ssa_type.erl
Outdated
| @@ -109,8 +109,40 @@ opt_start_1([Id | Ids], ArgDb, StMap0, FuncDb0, MetaCache) -> | |||
| opt_start_1(Ids, ArgDb, StMap, FuncDb, MetaCache) | |||
| end; | |||
| opt_start_1([], _CommittedArgs, StMap, FuncDb, _MetaCache) -> | |||
| %% Although unreachable functions are pruned when the list of | |||
| %% functions is first traversed above, it doesn't handle they case | |||
The beam_ssa_type:opt_continue/4 pass requires that type information is available for all arguments or else it will crash with a back trace similar to this: Sub pass ssa_opt_type_continue Function: '-f3/1-lc$^0/1-3-'/1 test362604.erl: internal error in pass beam_ssa_opt: exception error: no function clause matching beam_types:join([]) in function beam_ssa_type:join_arg_types/3 (beam_ssa_type.erl, line 449) in call from beam_ssa_type:opt_continue/4 (beam_ssa_type.erl, line 432) in call from beam_ssa_opt:ssa_opt_type_continue/1 (beam_ssa_opt.erl, line 449) in call from compile:run_sub_passes_1/3 (compile.erl, line 424) in call from beam_ssa_opt:phase/4 (beam_ssa_opt.erl, line 116) in call from beam_ssa_opt:fixpoint/6 (beam_ssa_opt.erl, line 99) in call from beam_ssa_opt:run_phases/3 (beam_ssa_opt.erl, line 85) If type analysis during beam_ssa_type:opt_start/2 concludes that a function is never called, type information for the callee will never be recorded, thus leaving no type information for the arguments in the function's entry in the function database, leading to the crash above. Although naively unreachable functions are pruned when the list of functions is first traversed in beam_ssa_type:opt_start/2, it doesn't handle they case when type inference concludes that a function is never called. This patch extends beam_ssa_type:opt_start/2 to, when all functions have been processed, prune non-exported functions for which #func_info.arg_types is just a list of empty dictionaries. That a function of zero arity is always considered reachable, is harmless as it won't crash opt_continue/4. Closes erlang#7509 Closes erlang#7478
|
Withdrawn as it masks the real bug. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The
beam_ssa_type:opt_continue/4pass requires that type information is available for all arguments or else it will crash with a back trace similar to this:If type analysis during
beam_ssa_type:opt_start/2concludes that a function is never called, type information for the callee will never be recorded, thus leaving no type information for the arguments in the function's entry in the function database, leading to the crash above.Although naively unreachable functions are pruned when the list of functions is first traversed in
beam_ssa_type:opt_start/2, it doesn't handle they case when type inference concludes that a function is never called. This patch extendsbeam_ssa_type:opt_start/2to, when all functions have been processed, prune non-exported functions for which#func_info.arg_typesis just a list of empty dictionaries. That a function of zero arity is always considered reachable, is harmless as it won't crash opt_continue/4.Closes #7509
Closes #7478