We get a lot of issues that basically boil down to "I passed malformed
LLVM IR to clang and it crashed". Clang does not perform IR verification
by default in (non-assertion-enabled) release builds, and that's
sensible for IR that Clang itself produces, which is expected to always
be valid. However, if people pass in their own handwritten IR, we should
report if it is malformed, instead of crashing. We should also report it
in a way that does not produce a crash trace and ask for a bug report,
as currently happens in assertions-enabled builds. This aligns the
behavior with how opt/llc work.
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