[lld] Ensure NoTrapAfterNoreturn is false for the wasm backend (PR #65876)

[Heejin Ahn via llvm-commits]

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@@ -159,6 +207,9 @@ bool WebAssemblyPeephole::runOnMachineFunction(MachineFunction &MF) {
       case WebAssembly::RETURN:
         Changed |= maybeRewriteToFallthrough(MI, MBB, MF, MFI, MRI, TII);
         break;
+      case WebAssembly::UNREACHABLE:
+        Changed |= eraseDeadCodeAroundUnreachable(MI, MBB);
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aheejin wrote:

+1 on splitting them, but I'm not sure if we should turn `NoTrapAfterNoreturn` off in the first place. The peephole optimization itself can be added regardless of whether we have `NoTrapAfterNoreturn` on or off I guess. (We need to check `noreturn` calls along with `UNREACHABLE`s)

https://github.com/llvm/llvm-project/pull/65876