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

Timestamp:

08/19/15 21:32:26 (10 years ago)

Author:

fuji

Comment:

—

cypress/Programming/CodeDebugging

@@ -177 +177 @@
 }}}
 
-== valgrid ==
+== Valgrind ==
 [http://valgrind.org/]
 
@@ -183 +183 @@
 
 
-=== Detecting Invalid Access  ===
-
+=== Detect Invalid Access  ===
+
+Example code: (this code has a bug)
 {{{#!c
 #include <stdio.h>
@@ -261 +262 @@
 }}}
 
-
+=== Detect Uninitialized Data Access  ===
+
+Example code: (this code has a bug)
+{{{#!c
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+  double * p = malloc(sizeof(double) * 10);
+  if (p[0] < 1) {
+    printf("p[0] < 1\n");
+  } else {
+    printf("p[1] >= 1\n");
+  }
+  return 0;
+}
+}}}
+
+{{{#!bash
+[fuji@cypress01-089 Valgrind]$ icc uninit.c
+[fuji@cypress01-089 Valgrind]$ ./a.out
+p[0] < 1
+[fuji@cypress01-089 Valgrind]$ icc -O0 -g uninit.c
+[fuji@cypress01-089 Valgrind]$ valgrind ./a.out
+==34643== Memcheck, a memory error detector
+==34643== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
+==34643== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
+==34643== Command: ./a.out
+==34643==
+==34643== Conditional jump or move depends on uninitialised value(s)
+==34643==    at 0x4005A9: main (uninit.c:6)
+==34643==
+==34643== Conditional jump or move depends on uninitialised value(s)
+==34643==    at 0x4005AB: main (uninit.c:6)
+==34643==
+p[0] < 1
+==34643==
+==34643== HEAP SUMMARY:
+==34643==     in use at exit: 80 bytes in 1 blocks
+==34643==   total heap usage: 1 allocs, 0 frees, 80 bytes allocated
+==34643==
+==34643== LEAK SUMMARY:
+==34643==    definitely lost: 80 bytes in 1 blocks
+==34643==    indirectly lost: 0 bytes in 0 blocks
+==34643==      possibly lost: 0 bytes in 0 blocks
+==34643==    still reachable: 0 bytes in 0 blocks
+==34643==         suppressed: 0 bytes in 0 blocks
+==34643== Rerun with --leak-check=full to see details of leaked memory
+==34643==
+==34643== For counts of detected and suppressed errors, rerun with: -v
+==34643== Use --track-origins=yes to see where uninitialised values come from
+==34643== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 6 from 6)
+}}}