Optimize Info Table Provenance Entries (IPEs) Map creation and lookup

Using a hash map reduces the complexity of lookupIPE(), making it non linear.

On registration each IPE list is added to a temporary IPE lists buffer, reducing
registration time. The hash map is built lazily on first lookup.

IPE event output to stderr is added with tests.

For details, please see
Note [The Info Table Provenance Entry (IPE) Map].

A performance test for IPE registration and lookup can be found here:
https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5724#note_370806

1 files changed, 10 insertions, 14 deletions

diff --git a/rts/include/rts/IPE.h b/rts/include/rts/IPE.h
index 81a6d553d0..07026979d8 100644
--- a/rts/include/rts/IPE.h
+++ b/rts/include/rts/IPE.h
@@ -1,6 +1,6 @@
 /* -----------------------------------------------------------------------------
  *
- * (c) The GHC Team, 2017-2018
+ * (c) The GHC Team, 2017-2021
  *
  * IPE API
  *
@@ -13,23 +13,19 @@
 
 #pragma once
 
-
-typedef struct InfoProv_{
-    char * table_name;
-    char * closure_desc;
-    char * ty_desc;
-    char * label;
-    char * module;
-    char * srcloc;
+typedef struct InfoProv_ {
+    char *table_name;
+    char *closure_desc;
+    char *ty_desc;
+    char *label;
+    char *module;
+    char *srcloc;
 } InfoProv;
 
 typedef struct InfoProvEnt_ {
-    StgInfoTable * info;
+    StgInfoTable *info;
     InfoProv prov;
-    struct InfoProvEnt_ *link;
 } InfoProvEnt;
 
-extern InfoProvEnt * RTS_VAR(IPE_LIST);               // registered IP list
-
 void registerInfoProvList(InfoProvEnt **cc_list);
-InfoProvEnt * lookupIPE(StgInfoTable *info);
+InfoProvEnt *lookupIPE(StgInfoTable *info);