Comment #5 on issue 5555 by [email protected]: UMR in proxy_script_fetcher_unittest http://code.google.com/p/chromium/issues/detail?id=5555
This is interesting. The way valgrind tracks UMR is completely different. The valgrind design works for these cases where you are copy and moving around uninitialized data that is never used. This is because they track and propagate uninitialized data through all operations / arithmetic operations, and they only warn you when you do something conditional on that data, for example if it was used in a compare, etc. http://valgrind.org/docs/origin-tracking2007.pdf """ Memcheck detects dangerous uses of undefined values by shadowing every register and memory byte with 8 V bits (‘V’ for “validity”) that indicate if the value bits are defined (i.e., initialized, or derived from other defined values). It updates and propagates these bits through memory and registers in parallel with normal computation. To minimize false positives Memcheck only warns users about uses of undefined values that can change the program’s behavior. These uses fall into four cases. 1. The program uses an undefined value in a conditional branch or conditionalmove, potentially changing the program’s control flow. 2. The program uses an undefined value as a branch target address, potentially changing the program’s control flow. 3. The program provides an undefined value as an input to a system call, potentially changing the program’s side effects. 4. The program uses an undefined value as the address in a load or store, potentially causing an incorrect value to be used, which could subsequently change the program’s control flow or side effects. """ -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Chromium-bugs" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/chromium-bugs?hl=en -~----------~----~----~----~------~----~------~--~---
