eventlog: Dump cost centre stack on each samplewip/ccs-sample-events

With this change it is possible to reconstruct the timing portion of a
`.prof` file after the fact. By logging the stacks at each time point
a more precise executation trace of the program can be observed rather
than all identical cost centres being identified in the report.

There are two new events:

1. `EVENT_PROF_BEGIN` - emitted at the start of profiling to communicate
the tick interval
2. `EVENT_PROF_SAMPLE_COST_CENTRE` - emitted on each tick to communicate the
current call stack.

Fixes #17322

1 files changed, 16 insertions, 0 deletions

diff --git a/rts/Trace.c b/rts/Trace.c
index de647f762b..c8a951a510 100644
--- a/rts/Trace.c
+++ b/rts/Trace.c
@@ -656,6 +656,7 @@ void traceHeapProfCostCentre(StgWord32 ccID,
     }
 }
 
+// This one is for .hp samples
 void traceHeapProfSampleCostCentre(StgWord8 profile_id,
                                    CostCentreStack *stack, StgWord residency)
 {
@@ -663,6 +664,21 @@ void traceHeapProfSampleCostCentre(StgWord8 profile_id,
         postHeapProfSampleCostCentre(profile_id, stack, residency);
     }
 }
+
+// This one is for .prof samples
+void traceProfSampleCostCentre(Capability *cap,
+                               CostCentreStack *stack, StgWord tick)
+{
+    if (eventlog_enabled) {
+        postProfSampleCostCentre(cap, stack, tick);
+    }
+}
+void traceProfBegin(void)
+{
+    if (eventlog_enabled) {
+        postProfBegin();
+    }
+}
 #endif
 
 #if defined(DEBUG)