[PATCH] D57982: [SanitizierCoverage] Avoid splitting critical edges when destination is a basic block containing unreachable

[Matt Morehouse via Phabricator via llvm-commits]

morehouse added a comment.

In D57982#1412282 <https://reviews.llvm.org/D57982#1412282>, @craig.topper wrote:

> A block can end in unreachable, but still have reachable code at the beginning. If the block calls a function that is known not to return, the next instruction after the call will be UnreachableInst. For example https://godbolt.org/z/6AGtOf


Sure, but that block is generally still not useful to instrument (for fuzzing).  When fuzzing, we save all inputs that either (1) increase coverage as measured by SanitizerCoverage, or (2) crash.  So if case 2 happens every time we touch a block that ends in unreachable, there's no point in instrumenting it so that case 1 happens too.


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