[PATCH] gdb 9.1: fix delay when doing -var-list-children From To command

[Паша Клюев]

If some C-program source code has
       int arrayInt[2000000];
Execute the command 
-var-create PD * arrayInt
and then call
-var-list-children --simple-values "VAR" 0 1000
 
The answer we will wait tens of seconds or a minute. We will wait tens of seconds or a minute for an answer. The wait time will depend on the size of the array.
 
 
diff  ./gdb-9.1/gdb/varobj.c ./gdb-9.1-patched/gdb/varobj.c
--- ./gdb-9.1/gdb/varobj.c    2020-02-08 15:50:14.000000000 +0300
+++ ./gdb-9.1-patched/gdb/varobj.c    2020-05-21 17:59:19.053876869 +0300
@@ -865,7 +865,25 @@
   while (var->children.size () < var->num_children)
     var->children.push_back (NULL);
 
-  for (int i = 0; i < var->num_children; i++)
+    /* patch begin
+    Cause:
+        Slow execution of -var-list-children command for big arrays
+    Example of source code:
+        int arrayInt[2000000];
+    Commands:
+        -var-create PD * arrayInt
+        -var-list-children --simple-values "PD" 0 1000
+    Output:
+         The -var-list-children command waits a very long time
+    Fix:
+        Implements cycle for only needed childrens, from 'from' to 'to' numbers
+        varobj_restrict_range function shift top for correct the 'from' and 'to' numbers
+    After fixing:
+        Command -var-list-children runs without delay
+     */
+  varobj_restrict_range (var->children, from, to);
+  for (int i = *from; i < *to; i++)
+    /* patch end */
     {
       if (var->children[i] == NULL)
     {
@@ -877,7 +895,13 @@
     }
     }
 
-  varobj_restrict_range (var->children, from, to);
+    /* patch begin
+    Cause:
+        see above
+    */
+    // varobj_restrict_range (var->children, from, to);
+    /* PD patch end */
+
   return var->children;
 }
 
 
 
--
Regards Pavel.