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, 35 insertions, 0 deletions

diff --git a/testsuite/tests/rts/ipeEventLog_fromMap.c b/testsuite/tests/rts/ipeEventLog_fromMap.c
new file mode 100644
index 0000000000..5bd9e4d034
--- /dev/null
+++ b/testsuite/tests/rts/ipeEventLog_fromMap.c
@@ -0,0 +1,35 @@
+#include "Rts.h"
+#include "RtsAPI.h"
+#include "rts/IPE.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+extern void dumpIPEToEventLog(void);
+InfoProvEnt *makeAnyProvEntry(Capability *cap, int i);
+
+int main(int argc, char *argv[]) {
+    hs_init(&argc, &argv);
+    Capability *cap = rts_lock();
+
+    HaskellObj one = rts_mkInt(cap, 1);
+
+    InfoProvEnt *provEnt_0 = makeAnyProvEntry(cap, 0);
+    InfoProvEnt *provEnt_1 = makeAnyProvEntry(cap, 1);
+
+    InfoProvEnt **ipeList_1 = malloc(sizeof(InfoProvEnt *) * 3);
+    ipeList_1[0] = provEnt_0;
+    ipeList_1[1] = provEnt_1;
+    ipeList_1[2] = NULL;
+
+    registerInfoProvList(ipeList_1);
+
+    // Query an IPE to initialize the underlying hash map.
+    lookupIPE(ipeList_1[0]->info);
+
+    // Trace all IPE events.
+    dumpIPEToEventLog();
+
+    rts_unlock(cap);
+    hs_exit();
+}