i#6444 mid-rseq-exit: Handle at-exit trace exit (#6456)

Augments the mid-rseq-trace-exit case to handle the rseq final instr
being reached but not passed. Adds a test case.

Issue: #6444

clients/drcachesim/tests/raw2trace_unit_tests.cpp

@@ -1984,9 +1984,12 @@ test_rseq_side_exit_inverted_with_timestamp(void *drcontext)
         check_entry(entries, idx, TRACE_TYPE_FOOTER, -1));
 }
 
-/* Tests a trace ending mid-rseq (i#6444). */
+/* Tests a trace ending mid-rseq (i#6444).
+ * If at_end is true, tests the endpoint just being reached but not pased;
+ * else tests the endpoint not being reached.
+ */
 bool
-test_midrseq_end(void *drcontext)
+test_midrseq_end_helper(void *drcontext, bool at_end)
 {
     std::cerr << "\n===============\nTesting mid-rseq trace end\n";
     instrlist_t *ilist = instrlist_create(drcontext);
@@ -2021,7 +2024,8 @@ test_midrseq_end(void *drcontext)
     raw.push_back(make_line_size());
     raw.push_back(make_timestamp());
     raw.push_back(make_core());
-    raw.push_back(make_marker(TRACE_MARKER_TYPE_RSEQ_ENTRY, offs_move3));
+    raw.push_back(
+        make_marker(TRACE_MARKER_TYPE_RSEQ_ENTRY, at_end ? offs_move2 : offs_move3));
     raw.push_back(make_block(offs_move1, 2));
     raw.push_back(make_block(offs_store, 1));
     raw.push_back(make_memref(42));
@@ -2060,6 +2064,13 @@ test_midrseq_end(void *drcontext)
         check_entry(entries, idx, TRACE_TYPE_FOOTER, -1));
 }
 
+bool
+test_midrseq_end(void *drcontext)
+{
+    return test_midrseq_end_helper(drcontext, /*at_end=*/false) &&
+        test_midrseq_end_helper(drcontext, /*at_end=*/true);
+}
+
 /* Tests pre-OFFLINE_FILE_VERSION_XFER_ABS_PC (module offset) handling. */
 bool
 test_xfer_modoffs(void *drcontext)

clients/drcachesim/tracer/raw2trace.cpp

@@ -579,11 +579,21 @@ raw2trace_t::process_offline_entry(raw2trace_thread_data_t *tdata,
                 tdata->error = "Missing thread id";
                 return false;
             }
-            if (tdata->rseq_buffering_enabled_ &&
-                // Deliberately pass 0 as the PC so it's treated as an instru
-                // exit and we just dump the buffer as-is.
-                !adjust_and_emit_rseq_buffer(tdata, 0, 0))
-                return false;
+            if (tdata->rseq_buffering_enabled_) {
+                // Finish off the rseq buffer.
+                addr_t next_pc;
+                if (tdata->rseq_past_end_) {
+                    // The thread exited right as we hit the lst instr.
+                    next_pc = tdata->rseq_end_pc_;
+                } else {
+                    // We exited mid-sequence.
+                    // Deliberately pass 0 as the PC so it's treated as an instru
+                    // exit and we just dump the buffer as-is.
+                    next_pc = 0;
+                }
+                if (!adjust_and_emit_rseq_buffer(tdata, next_pc, 0))
+                    return false;
+            }
             log(2, "Thread %d exit\n", (uint)tid);
             buf += trace_metadata_writer_t::write_thread_exit(buf, tid);
             *end_of_record = true;