vmgen: fix incorrect code generation for `lent`/`var` deref

zerbina commented 3 months ago

Summary

Fix reading from a var/lent view of an unsigned integer (with bit- width <= 32) producing incorrect values, when using the VM.

change genDerefView to take the cnkDerefView node as input, so that it has access to the type of the result
the type of the view (not the storage type) was previously passed to the genRegLoad call, resulting in no NarrowU instruction to be emitted for the memory access, and the value thus being sign-extended

saem commented 3 months ago

/merge

github-actions[bot] commented 3 months ago

Merge requested by: @saem

Contents after the first section break of the PR description has been removed and preserved below:

## Notes for Reviewers * it's not feasible at the moment, but `var`/`lent` needs to be the same as pointers, for code reaching the code generators