Method and apparatus using variable ranges to support symbolic debugging of optimized code

A method for determining and recording, during optimization of computer programming code compiled for execution on a computing system, ranges of instructions within the computer programming code for which user resources reside in certain locations within the computing system, the method comprising the following steps performed by a computer of:

• (a) dividing the computer programming code up into basic blocks of straight line code sequences of instructions with a single entry point and a single exit point;
• (b) calculating webs for each user resource;
• (c) determining a range of instructions within each basic block when webs for each user resource are alive;
• (d) allocating, for each determined range of instructions for each web, locations in which user resources are stored;
• and,
• (e) storing in a table a description of allocated locations for each determined range of instructions.

In a computing system which includes a debugger which is used to debug compiled code generated by a compiler from source code, an improvement to the computing system comprising:

• a resource table generated by the computer system during compilation of the compiled code, the resource table including a plurality of resource table entries, the entries describing resources in the compiled code;
• a debug symbol table generated by the computer system during compilation of the compiled code, the debug symbol table including a plurality of debug symbol table entries, each debug symbol table entry including data which describes a resource in the source code, wherein when a first resource table entry from the plurality of resource table entries describes a first resource in the compiled code which is equivalent to a first resource in the source code, the first resource table entry will contain a pointer which points to a first debug symbol table entry which describes the first resource in the source code;
• and,
• a range table generated by the computing system during compilation of the compiled code, the range table including a range list for at least one of the resources in the source code, the range list including at least one range of instructions executable by the computing system, and for each of the at least one range of instructions, a location where the resource resides in the computing system when the computing system executes the at least one range of instructions,
• wherein when a first range list for the first resource in the source code is in the range table, the first debug symbol table entry will contain a pointer which points to the first range list.