valgrind use cases

[ejrgilbert]

e.g. track liveness with mallocs (what memory regions are currently live) along with memory accesses (am I accessing a region of memory that is currently live?)

General

• Output commentary should have clear marking as not program output, e.g.:

  ==12345== some-message-from-Valgrind
  

• Print a stack trace for each error and warning
• When an error is reported, it is given the full commentary for only 1 instance, e.g.:

  ==25832== Invalid read of size 4
  ==25832==    at 0x8048724: BandMatrix::ReSize(int, int, int) (bogon.cpp:45)
  ==25832==    by 0x80487AF: main (bogon.cpp:66)
  ==25832==  Address 0xBFFFF74C is not stack'd, malloc'd or free'd
  ==25832== Invalid read of size 4
  ==25832==    at 0x8048724: BandMatrix::ReSize(int, int, int) (bogon.cpp:45)
  ==25832==    by 0x80487DD: main (bogon.cpp:69)
  

• Give errors in the order users should fix them
  • For example, a program which copies uninitialised values to several memory locations, and later uses them, will generate several error messages. The first such error message should give the most direct clue to the root cause of the problem.
• Have a quiet mode that only outputs errors (not warnings)
• Create option to stop after a certain number of errors
• Timestamp option using sys.time or similar

Memcheck

• Invalid read: say size, memory location, and where in the code it is
• A comment is given for what the likely error cause is
• Output the error before the code executes, as it will likely segfault
• Set a limit for the number of errors you collect in order to not bloat it
• Have toggleable warnings for unsafe things (incrementing pointers and the like)
• Create option to stop after a certain number of errors

[wavid-b]

Here is where I'm going to be putting the info https://docs.google.com/document/d/1dpfPOlc9bpuV2BuPVpwjU-3xXUa50yNfixyTND91p7Q/edit?usp=sharing

DM me for edit access and I'll add you