TotalView Users Guide - CI Wiki

Using Watchpoints
Platform Assembler Code
IBM AIX .csect .data{RW}, 3
.globl TVDB_patch_base_address
.globl TVDB_patch_end_address
TVDB_patch_base_address:
.space PATCH_SIZE
TVDB_patch_end_address:
SGI IRIX .data
.align 3
.globl TVDB_patch_base_address
.globl TVDB_patch_end_address
TVDB_patch_base_address:
.space PATCH_SIZE
TVDB_patch_end_address:
To use the static patch space assembler code:
1 Use an ASCII editor and place the assembler code into a file named
tvdb_patch_space.s.
2 Replace the PATCH_SIZE tag with the decimal number of bytes you want.
This value must be a multiple of 8.
3 Assemble the file into an object file by using a command such as:
cc –c tvdb_patch_space.s
On SGI IRIX, use –n32 or –64 to create the correct object file type.
4 Link the resulting tvdb_patch_space.o into your program.
Using Watchpoints
TotalView lets you monitor the changes that occur to memory locations by
creating a special type of action point called a watchpoint. You most often
use watchpoints to find a statement in your program that is writing to
places to which it shouldn’t be writing. This can occur, for example, when
processes share memory and more than one process writes to the same
location. It can also occur when your program writes off the end of an array
or when your program has a dangling pointer.
Topics in this section are:
� “Using Watchpoints on Different Architectures” on page 374
� “Creating Watchpoints” on page 375
� “Watching Memory” on page 377
� “Triggering Watchpoints” on page 377
� “Using Conditional Watchpoints” on page 378
TotalView watchpoints are called modify watchpoints because TotalView only
triggers a watchpoint when your program modifies a memory location. If a
program writes a value into a location that is the same as what is already
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