Changes between Version 3 and Version 4 of cypress/Programming/CodeDebugging


Ignore:
Timestamp:
Aug 19, 2015 9:32:26 PM (6 years ago)
Author:
fuji
Comment:

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  • cypress/Programming/CodeDebugging

    v3 v4  
    177177}}}
    178178
    179 == valgrid ==
     179== Valgrind ==
    180180[http://valgrind.org/]
    181181
     
    183183
    184184
    185 === Detecting Invalid Access  ===
    186 
     185=== Detect Invalid Access  ===
     186
     187Example code: (this code has a bug)
    187188{{{#!c
    188189#include <stdio.h>
     
    261262}}}
    262263
    263 
     264=== Detect Uninitialized Data Access  ===
     265
     266Example code: (this code has a bug)
     267{{{#!c
     268#include <stdio.h>
     269#include <stdlib.h>
     270
     271int main() {
     272  double * p = malloc(sizeof(double) * 10);
     273  if (p[0] < 1) {
     274    printf("p[0] < 1\n");
     275  } else {
     276    printf("p[1] >= 1\n");
     277  }
     278  return 0;
     279}
     280}}}
     281
     282{{{#!bash
     283[fuji@cypress01-089 Valgrind]$ icc uninit.c
     284[fuji@cypress01-089 Valgrind]$ ./a.out
     285p[0] < 1
     286[fuji@cypress01-089 Valgrind]$ icc -O0 -g uninit.c
     287[fuji@cypress01-089 Valgrind]$ valgrind ./a.out
     288==34643== Memcheck, a memory error detector
     289==34643== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
     290==34643== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
     291==34643== Command: ./a.out
     292==34643==
     293==34643== Conditional jump or move depends on uninitialised value(s)
     294==34643==    at 0x4005A9: main (uninit.c:6)
     295==34643==
     296==34643== Conditional jump or move depends on uninitialised value(s)
     297==34643==    at 0x4005AB: main (uninit.c:6)
     298==34643==
     299p[0] < 1
     300==34643==
     301==34643== HEAP SUMMARY:
     302==34643==     in use at exit: 80 bytes in 1 blocks
     303==34643==   total heap usage: 1 allocs, 0 frees, 80 bytes allocated
     304==34643==
     305==34643== LEAK SUMMARY:
     306==34643==    definitely lost: 80 bytes in 1 blocks
     307==34643==    indirectly lost: 0 bytes in 0 blocks
     308==34643==      possibly lost: 0 bytes in 0 blocks
     309==34643==    still reachable: 0 bytes in 0 blocks
     310==34643==         suppressed: 0 bytes in 0 blocks
     311==34643== Rerun with --leak-check=full to see details of leaked memory
     312==34643==
     313==34643== For counts of detected and suppressed errors, rerun with: -v
     314==34643== Use --track-origins=yes to see where uninitialised values come from
     315==34643== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 6 from 6)
     316}}}