A focused walkthrough of Stage 2 in the REX OpenMP pipeline: converting ompparser's OpenMPIR into Sage/ROSE `SgOmp*` nodes with correct nesting, clause structure, and scope-aware expression parsing.

When LLVM offloading changes, a source-to-source compiler can keep building but stop running. This post explains the failure modes, the debugging workflow, and the compatibility strategy REX uses to stay stable across LLVM toolchain migrations.

A deep look at the REX helper/runtime boundary: how offload entries are emitted, how a CUBIN image is registered with libomptarget, how rex_kmp.h rewrites runtime calls, and why init/fini are handled the way they are.

A deep walkthrough of the REX OpenMP GPU lowerer: directive dispatch, outlining, runtime map arrays, `__tgt_kernel_arguments` construction, generated files, and the tests that keep multi-kernel lowering correct.

An end-to-end walkthrough of REX's OpenMP architecture: why it owns OpenMP parsing, how ompparser feeds Sage AST construction, how lowering generates host and device code, and how the test system keeps the pipeline honest.