Add -finfo-table-map which maps info tables to source positions

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.

1 files changed, 2 insertions, 0 deletions

diff --git a/rts/rts.cabal.in b/rts/rts.cabal.in
index 108b4d6b9b..427c78c40f 100644
--- a/rts/rts.cabal.in
+++ b/rts/rts.cabal.in
@@ -166,6 +166,7 @@ library
                       rts/Parallel.h
                       rts/PrimFloat.h
                       rts/Profiling.h
+                      rts/IPE.h
                       rts/Signals.h
                       rts/SpinLock.h
                       rts/StableName.h
@@ -448,6 +449,7 @@ library
                ProfilerReport.c
                ProfilerReportJson.c
                Profiling.c
+               IPE.c
                Proftimer.c
                RaiseAsync.c
                RetainerProfile.c