Consistent Views at Recommended Breakpoints

When users of source-level debugging and monitoring programs choose to inspect the state of the program at a certain line number, it is desirable that effects of logically prior source statements be in the picture presented to the user, and that effects of subsequent statements not be in it. However, as optimizations change, drop and reorder code fragments, concerted effort is required of the compiler and the debug information consumer to select appropriate inspection points, and to reconstruct coherent pictures for the user. We propose a robust method for the compiler to select and annotate meaningful, consistent inspection points, and debug information extensions to support multiple coherent pictures at a single program location. They enable debug information consumers to stop at inspection points that could not be represented otherwise, and to advance to the user-visible states of subsequent source lines, even in the absence of intervening executable instructions.