Codegen emits dangling LLVM metadata reference (!alias.scope !201) — blocks multi-module compile #71

Summary

Perry 0.5.78 emits a dangling LLVM metadata reference in the IR for some modules, causing clang to fail:

error: use of undefined metadata '!201'
  store i8 %r35, ptr %r34, !alias.scope !201, !noalias !301

The metadata !201 is referenced in the IR but never defined. Happens specifically in src/types/codecs/scalars.ts (the @perry/postgres codec file) but likely affects any module where the new alias-scope metadata from the escape-analysis / scalar-replacement passes (#66, v0.5.76) is emitted without a matching definition.

Repro

perry compile bench/bench-this.ts -o /tmp/bench-this

Error compiling module 'src/types/codecs/scalars.ts':
  .ll:2789:42: error: use of undefined metadata '!201'
    store i8 %r35, ptr %r34, !alias.scope !201, !noalias !301

The failing IR is left at the temp path shown in the error. All other modules in the project compile fine — only scalars.ts triggers it.

Likely cause

The !alias.scope / !noalias metadata was added by the escape-analysis scalar-replacement pass (v0.5.73 / v0.5.76). The metadata numbering is probably emitted assuming a contiguous !0 through !N sequence, but some intermediate pass (dead-code elimination? function inlining?) drops a metadata definition while leaving a reference.

The IR file at the temp path has the full context if needed.

Impact

Blocks compilation of @perry/postgres (and any project whose codegen hits the same path) on 0.5.78. Single-file programs that don't trigger the scalar-replacement pass compile fine.

Environment

• Perry 0.5.78
• macOS 26 / Apple Silicon
• Repro: perry compile bench/bench-this.ts in @perry/postgres repo