Understand roles before names

A register panel contains many unfamiliar names and long hexadecimal values. Start with the program counter, the stack pointer, and the registers used to return results. RIP and RSP are common names on x86-64, while other architectures use different names. GDB’s $pc and $sp aliases are useful for looking at the current instruction and stack memory. A register’s meaning also depends on the target architecture and calling convention. Do not assume that a rule from one platform applies to every executable.

Use the program counter to follow control flow

The current instruction address identifies the next instruction to execute. Arithmetic is often followed by a nearby address, while branches, calls, and returns can move execution much farther. An address jump is not by itself evidence of a corrupt pointer. Check whether the preceding instruction was a call, return, or conditional branch. Following a few function entries and returns helps connect register changes with control flow. Compare snapshots taken while the program is stopped; continuously changing values in a running process are a different kind of observation.

Bits do not carry source-level types

A register value can represent an integer, an address, flags, or a temporary calculation. The same bit pattern can have different meanings in different instructions. On x86-64, EAX and RAX are not independent storage: writing EAX clears the upper 32 bits of RAX, while smaller subregister writes have different rules. Read the operand size before interpreting a change. If a hexadecimal value looks unfamiliar, do not immediately treat it as a pointer. First identify the operation that wrote it and the role it has in the current calculation.

A highlight is a clue, not a verdict

DBG Desk highlights registers that changed since the previous refresh in blue. A change is not necessarily an error. Calls may legitimately overwrite temporary registers, and return locations depend on the calling convention and result type. Check which instruction wrote the value and where that value goes next. Distinguish values that must survive a call from values available for temporary use. The goal is to connect observed bits to the meaning expected by the program.

Trace one small integer

Choose the accumulate call with input 2, which should return 7. There need not be a register named after the source variable value. Follow the instructions that read the input and produce the result, then inspect how the caller adds it to the total. A register may be reused afterward without invalidating the calculation. Compare observations from corresponding stops in the same build.