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* IPE: Give all constructor and function tables locationswip/con-infoMatthew Pickering2021-03-031-18/+12
| | | | | | | | | | During testing it was observed that quite a few info tables were not being given locations (due to not being assigned source locations, because they were not enclosed by a source note). We can at least give the module name and type for such closures even if no more accurate source information. Especially for constructors this helps find them in the STG dumps.
* Add option to give each usage of a data constructor its own info tableMatthew Pickering2021-03-031-8/+114
| | | | | | | | | | | | | The `-fdistinct-constructor-tables` flag will generate a fresh info table for the usage of any data constructor. This is useful for debugging as now by inspecting the info table, you can determine which usage of a constructor caused that allocation rather than the old situation where the info table always mapped to the definition site of the data constructor which is useless. In conjunction with `-hi` and `-finfo-table-map` this gives a more fine grained understanding of where constructor allocations arise from in a program.
* Add -finfo-table-map which maps info tables to source positionsMatthew Pickering2021-03-031-0/+140
This new flag embeds a lookup table from the address of an info table to information about that info table. The main interface for consulting the map is the `lookupIPE` C function > InfoProvEnt * lookupIPE(StgInfoTable *info) The `InfoProvEnt` has the following structure: > typedef struct InfoProv_{ > char * table_name; > char * closure_desc; > char * ty_desc; > char * label; > char * module; > char * srcloc; > } InfoProv; > > typedef struct InfoProvEnt_ { > StgInfoTable * info; > InfoProv prov; > struct InfoProvEnt_ *link; > } InfoProvEnt; The source positions are approximated in a similar way to the source positions for DWARF debugging information. They are only approximate but in our experience provide a good enough hint about where the problem might be. It is therefore recommended to use this flag in conjunction with `-g<n>` for more accurate locations. The lookup table is also emitted into the eventlog when it is available as it is intended to be used with the `-hi` profiling mode. Using this flag will significantly increase the size of the resulting object file but only by a factor of 2-3x in our experience.