[llvm] [CodeExtractor] Terminate callsite blocks to new `noreturn` functions with `unreachable` (PR #84682)

[via llvm-commits]

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@@ -1010,6 +1010,18 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
 
     newFunction->addFnAttr(Attr);
   }
+
+  if (NumExitBlocks == 0) {
+    // Mark the new function `noreturn` if applicable. Terminators which resume
+    // exception propagation are treated as returning instructions. This is to
+    // avoid inserting traps after calls to outlined functions which unwind.
+    if (none_of(Blocks, [](const BasicBlock *BB) {
+          const Instruction *Term = BB->getTerminator();
+          return isa<ReturnInst>(Term) || isa<ResumeInst>(Term);
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goldsteinn wrote:

Think that should be a follow up patch.
FWIW I tested this w/ hotcoldsplitting enabled (+ split all no-returns) on llvm-test-suite/spec/bootstrap and saw no issues.

https://github.com/llvm/llvm-project/pull/84682