US 6,185,597 B2 · Method and system for expanding a buried stack frame

Abstract

A method and system for growing stack frames is described. According to the invention, actual growth of a stack frame buried below the top of the stack is delayed until such time as the frame is returned to the top of the stack. The invention can be applied, for example, in a source code debugger to provide an improved Edit and Continue capability. In one aspect, the invention is implemented in a computer system that includes a processor (CPU), a stack of frames accessible to the processor, and a program for execution by the processor. The program is composed of a set of procedures. The processor begins executing a procedure of the set and places a stack frame associated with the execution of the procedure on top of the stack. This first stack frame includes a reserved location that can be used later to record an amount or increment by which to grow the frame. The processor begins executing another procedure (or another instance of the same procedure) and places a second stack frame associated with this second procedure execution at the top of the stack above the first frame. The processor receives a command to increase the size of the first frame by a specified increment. While the second frame is above the first frame in the stack, the processor saves the specified increment in the reserved frame location of the buried first stack frame. Thereafter, the processor brings the first frame back to the top of the stack, retrieves the saved increment from the reserved frame location of the first frame, and increases the size of the first frame by the specified increment. The processor then can continue the first procedure execution with the first frame thus increased in size.

Claims21

Dependent claims

In a computer system comprising a processor, a stack holding stack frames and having a top, a program having a set of procedures, and a debugging facility for controlling execution of the procedures by the processor, a method of growing one of the stack frames comprising the computer-implemented steps of:

commencing execution of a first of the procedures of the set of procedures on the processor;
in response to commencing execution of the first procedure, placing at the top of the stack a first stack frame associated with execution of the first procedure;
during execution of the first procedure,
suspending execution of the first procedure;
commencing execution of a second of the procedures in the set of procedures on the processor;
and
in response to commencing execution of the second procedure, placing at the top of the stack above the first frame a second stack frame associated with the execution of the second procedure;
during execution of the second procedure,
receiving in the debugging facility a request to add a local variable to the first procedure;
determining an amount by which to increase the size of the first frame to provide adequate working storage for the local variable;
and
saving an indication of the determined amount;
and
after completing the execution of the second procedure,
bringing the first frame to the top of the stack;
retrieving the indication of the determined amount;
with the debugging facility, adding the local variable to the first procedure by increasing the size of the first frame by the determined amount;
and
resuming execution of the first procedure;
and
during the resumed execution of the first procedure, using the added local variable,
whereby the request to add a local variable to the first procedure can be received while the second procedure is executing.

19 more elements

Dependencies are inferred from the claim text.

Method and system for expanding a buried stack frame

Life of this patent

Method and system for expanding a buried stack frame

Life of this patent

Abstract

Claims21