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Declarative Memory


In addition to physical and virtual memory layers, we add another abstraction, the memory layer associated with source code values. We call it declarative memory. This term is not to be confused with declarative (or explicit) memory in neuropsychology. Memory corresponding to values in source code may be linearly organized but translated to a different layout by a compiler, or different values can be translated to the same virtual memory location. For example, in Rust (which prompted us to introduce this new memory concept), the following tuple is mapped to a different memory layout:

let i: i32 = 1;
let tuple: (bool, i32, &i32) = (true, 0, &i);

0:000> dt tuples!tuple
Local var @ 0x5c3196f2f0 Type tuple$<bool,i32,ref$<i32> >
   +0x004 __0              : 1
   +0x000 __1              : 0n0
   +0x008 __2              : 0x0000005c`3196f2ec  -> 0n1

0:000> dq 0x5c3196f2f0 L2
0000005c`3196f2f0  00000001`00000000 0000005c`3196f2ec

0:000> dd 0x5c3196f2f0 L4
0000005c`3196f2f0  00000000 00000001 3196f2ec 0000005c

Another virtual memory cell reuse example is the Optimized Code (function parameter reuse) memory analysis pattern.

Whereas in trace and log analysis, where there is the Declarative Trace analysis pattern where a declarative trace statement in source code may correspond to many actual trace statements, a kind of 1 to 0..N correspondence, declarative memory is usually M to N, where M >= N.
Similar to virtual-to-physical mapping, where the amount of virtual memory is greater than the amount of physical memory, the amount of declarative memory can be greater than the amount of virtual memory.