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, 18 insertions, 0 deletions

diff --git a/rts/IPE.h b/rts/IPE.h
new file mode 100644
index 0000000000..48b4c62f00
--- /dev/null
+++ b/rts/IPE.h
@@ -0,0 +1,18 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1998-2005
+ *
+ * Support for IPE
+ *
+ * ---------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <stdio.h>
+#include "Rts.h"
+
+#include "BeginPrivate.h"
+
+void dumpIPEToEventLog(void);
+
+#include "EndPrivate.h"