In D88363#2319157, @jmorse wrote:

In D88363#2317241, @Mordante wrote:

Can you explain the kind of issues you're having?

At the shallowest level, our -O1 produces different IR and fails the test, which is more or less our problem; however my understanding is that tests in the LLVM project / subprojects should aim to test as little amount of code as possible. Relying on all of -O1 makes it a brittle test -- changes to any optimisation pass enabled in -O1 could cause this test to fail spuriously.

Instead, I believe the test should be in two parts:

• One checking clang produces the correct /unoptimised/ IR output
• One or more checking that the consuming IR passes do-the-right-thing

Looks good. Good idea to add tests to verify that we match __builtin_except().