The next REX GPU performance post: why scalar target parameters should not be lowered like address-based mapped objects, how REX identifies safe literal parameters, and how host packing plus device unpacking moved the generated code closer to LLVM's modern OpenMP launch ABI.

The next REX GPU performance post: why launch geometry is a compiler policy problem, how REX separates explicit user launch clauses from compiler-owned defaults, and why fair optimization means shrinking only the parts of the launch contract that the user did not freeze.

The second performance-root-cause post in the REX GPU campaign: how the remaining `nn` gap moved from host lifecycle cost to device-loop shape, why the old XOMP static scheduler path was too expensive for canonical target loops, and how REX replaced it with generic direct grid-stride lowering.

The first performance-root-cause post in the REX GPU campaign: how a large early `nn` slowdown turned out to be misplaced one-time offload registration work, why the generated source had to place `rex_offload_init()` before benchmark timing, and how lowering tests now protect that invariant.

A focused walkthrough of the benchmark build contract in REX: how the same application becomes a native LLVM OpenMP-offload binary and a REX-generated binary, why both must share the same LLVM runtime family, and how identical run commands keep the comparison honest.

A focused explanation of the top-layer benchmark contract in REX: same runtime stack, same inputs, normalized correctness, benchmark-appropriate timing, clause-preserving fairness, and results interpreted as evidence rather than a simplistic scoreboard.

A focused case for keeping REX's GPU benchmark layer narrow: benchmarks are the final reality check, but they are the wrong place to first detect parser drift, semantic normalization bugs, or simple lowering-structure regressions.

A focused case for why REX still needs full GPU benchmark runs after parser, AST, lowering, and CPU-equivalence tests already pass: only real applications exposed misplaced offload init, bad timing proxies, baseline drift, and full-stack integration issues.

A focused walkthrough of the correctness side of REX benchmark validation: stripping non-semantic output lines, using reduced-output modes when benchmarks hide their results, and distinguishing current native-versus-REX agreement from stale-baseline drift.

A focused methodology post on fair GPU benchmark comparisons between REX and native LLVM: same runtime stack, clause-preserving launch policy, benchmark-appropriate timing sources, and correctness rules that do not confuse drift with regression.