[memprof] Fix the text format print for live on exit blocks.

[snehasish]

Summary

We dropped the printing of live on exit blocks in rG1243cef245f6 -
the commit changed the insertOrMerge logic. This regression was
hard to catch since there was no further text printed out to indicate
the subsequent blocks were from the block table. This commit adds
another print to separate out these two printed sections. When post
processing the text profiles, the "live on exit" is informative only. The
actual MIBs are printed again as part of the recorded MIBs.

[tejohnson]

compiler-rt/lib/memprof/memprof_allocator.cpp

257

I'm confused - shouldn't this handling print any MIB blocks merged during InsertLiveBlocks (i.e. so include the live on exit blocks)?

I think the print I had of "Live on exit:" below was misleading/incorrect - I meant to distinguish those that we evicted from the MIB table when it was finite from the full table at the end which included the live on exit blocks. We should simply remove that "Live on exit" message below, since it isn't needed anymore and wasn't really correct before. I don't believe we were ever printing just those live on exit, separately from the full MIB table.

[snehasish]

Remove the live on exit print statement.
Update the memprof_profile_dump.cpp test.

[snehasish]

Actually update the test this time.

[snehasish]

Remove -Wl,-build-id from the test (meant to be a local change).

[snehasish]

Thanks, PTAL.

compiler-rt/lib/memprof/memprof_allocator.cpp

257

Yes, it does. I interpreted the prior "Live on exit" print statements as a snapshot of what was live followed by all the recorded mibs (incl. live mibs). I assumed it was used for debugging etc so I wanted to retain the behaviour. I noted this in the description of the patch. Removing this sounds good to me.

[tejohnson]

lgtm, sorry for the confusion!

compiler-rt/lib/memprof/memprof_allocator.cpp

struct Allocator {
   void FinishAndWrite() {
     if (print_text && common_flags()->print_module_map)
       DumpProcessMap();
 
     allocator.ForceLock();
 
     InsertLiveBlocks();
     if (print_text) {
+      if (!flags()->print_terse)
+        Printf("Recorded MIBs (incl. live on exit):\n");
       MIBMap.ForEach(PrintCallback,
                      reinterpret_cast<void *>(flags()->print_terse));
       StackDepotPrintAll();
     } else {
       // Serialize the contents to a raw profile. Format documented in
       // memprof_rawprofile.h.
       char *Buffer = nullptr;
 
       MemoryMappingLayout Layout(/*cache_enabled=*/true);
       u64 BytesSerialized = SerializeToRawProfile(MIBMap, Layout, Buffer);
       CHECK(Buffer && BytesSerialized && "could not serialize to buffer");
       report_file.Write(Buffer, BytesSerialized);
     }
 
     allocator.ForceUnlock();
   }
 
   // Inserts any blocks which have been allocated but not yet deallocated.
   void InsertLiveBlocks() {
-    if (print_text && !flags()->print_terse)
-      Printf("Live on exit:\n");
-
     allocator.ForEachChunk(
         [](uptr chunk, void *alloc) {
           u64 user_requested_size;
           Allocator *A = (Allocator *)alloc;
           MemprofChunk *m =
               A->GetMemprofChunk((void *)chunk, user_requested_size);
           if (!m)
             return;

compiler-rt/test/memprof/TestCases/memprof_profile_dump.cpp

-// RUN: %clangxx_memprof  %s -o %t
+// RUN: %clangxx_memprof %s -o %t
 
 // RUN: %env_memprof_opts=print_text=true:log_path=stdout %run %t | FileCheck --check-prefix=CHECK-TEXT %s
-// RUN: %env_memprof_opts=print_text=true:log_path=stdout,print_text=false %run %t > %t.memprofraw
+// RUN: %env_memprof_opts=log_path=stdout %run %t > %t.memprofraw
 // RUN: od -c -N 8 %t.memprofraw | FileCheck --check-prefix=CHECK-RAW %s
 
 #include <sanitizer/memprof_interface.h>
 #include <stdlib.h>
 #include <string.h>
 int main(int argc, char **argv) {
   char *x = (char *)malloc(10);
   memset(x, 0, 10);
   free(x);
   __memprof_profile_dump();
   x = (char *)malloc(10);
   memset(x, 0, 10);
   free(x);
   return 0;
 }
 // We should get 2 rounds of profile info, one from the explicit dump request,
 // and one at exit.
+//
+// CHECK-TEXT: Recorded MIBs (incl. live on exit):
 // CHECK-TEXT: Memory allocation stack id
 // CHECK-TEXT: Stack for id
+//
+// CHECK-TEXT: Recorded MIBs (incl. live on exit):
 // CHECK-TEXT: Memory allocation stack id
 // CHECK-TEXT: Stack for id
 //
 // For the raw profile just check the header magic. The following check assumes that memprof
 // runs on little endian architectures.
 // CHECK-RAW: 0000000 201   r   f   o   r   p   m 377