TotalView Users Guide - CI Wiki

Figure 103: Register Union
Debugging IBM Cell Broadband Engine Programs
When you exit from your program or when you manually save breakpoints,
TotalView writes breakpoints for each SPU thread share group. The next
time your program loads an SPU executable into an SPU context, these
breakpoints are read back in.
Within the CLI your focus determines if the breakpoint is shared on
unshared. For example::
Focus Type of Breakpoint
dfocus t 1.-1 dbreakpoint main Unshared breakpoint
dfocus p 1.-1 dbreakpoint main Unshared breakpoint
dfocus d 1.-1 dbreakpoint main Shared breakpoint
dfocus g 1.-1 dbreakpoint main Shared breakpoint
Registers, Unions, and Casting
SPU registers are 128-bits wide. In most cases, you'll be loading data into
the registers in different ways. For example, you might be using the SPU as
a vector processor and be loading 4 32-bit values into a register.
TotalView defines a union that helps you see this data in seven different
ways, as is shown in the following figure.
This picture shows how TotalView displays register R0. TotalView defines
the data type of this register as union $spu_vec128. If you dive (doubleclick)
on a member in the union, TotalView shows the contents of the register
as if they were defined in this way. For example, diving in v4_float tells
TotalView to display this information as an array of four floating point numbers.
After diving on a union member, the displayed values can be edited and
stored back into memory.
If this union doesn't describe your data, you can tell the TotalView to display
it in the way you want by altering the information in this window's Type
field. However, casting the value into a data type smaller than 128-bits
pulls the value from the preferred slot of the register that is appropriate for
the type’s size.
TotalView Reference Guide: version 8.7 143