tree dd1708c2bcb3c03322c185b0bb49e888acb9493a
parent a9d6c34d868affa55c403ce82428882b825441a2
author David Neto <dneto@google.com> 1640018815 +0000
committer Tint LUCI CQ <tint-scoped@luci-project-accounts.iam.gserviceaccount.com> 1640018815 +0000

spirv-writer: Fix termination of basic blocks

There are a few places where a branch or return is created,
conditionally on whether a terminator was the last thing seen.
The goal is to generate a SPIR-V basic block terminator exactly
when needed, and to avoid generating a branch or return immediately
after a prior terminator.

Previously, the decision was based on the last thing seen in the AST.
But we should instead check the emitted SPIR-V instead.

This fixes cases such as a break or return inside an else-if.
That's because an if/elseif is actually a selection inside a selection.
Looking at the AST only works when trying to terminate the *inside*
selection.  In the outer recursive call, the last AST node is
no longer a terminator, and we would skip generating the branch
to the merge block.

Fixed: tint:1315
Change-Id: I6b886ce85d1d681f2063997e469e0c1b4e5973a2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/73480
Kokoro: Kokoro <noreply+kokoro@google.com>
Auto-Submit: David Neto <dneto@google.com>
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: James Price <jrprice@google.com>