Multiplicity — Allocation Multiplicity Classification

Allocation multiplicity classifies each allocation site (global, stack, or heap) as either Unique (executed at most once per program invocation) or Summary (potentially executed multiple times).

Headers: include/Analysis/Multiplicity/

Implementation: lib/Analysis/Multiplicity/

Public API: - lotus::analysis::multiplicity::classifyModuleMultiplicity

— classify all allocations in a module

Overview

The analysis inspects every allocation site in a module and assigns a multiplicity classification:

• Unique — the allocation executes at most once per program run. Applies to: - All global variables (always Unique) - Stack allocations (alloca) in functions without loops - Heap allocations (malloc/calloc/realloc) in functions that are

  both loop-free and called from at most one call site

• Summary — the allocation may execute multiple times. Applies to: - Allocations inside loop-bearing functions - Heap allocations in functions called from multiple call sites

Heap Allocation Detection

Heap allocation functions are identified using the AliasSpecManager, which recognizes standard allocators (malloc, calloc, realloc, operator new, etc.) by their known function roles.

Usage

#include "Analysis/Multiplicity/MultiplicityClassifier.h"

llvm::Module &M = ...;
auto result = lotus::analysis::multiplicity::
    classifyModuleMultiplicity(M);

for (const auto &[value, mult] : result.allocations) {
  if (mult == lotus::analysis::multiplicity::AllocationMultiplicity::Unique)
    errs() << "Unique allocation: " << *value << "\n";
}