[llvm] [DFAJumpThreading] Unify equivalent states (PR #162447)

[Nikita Popov via llvm-commits]

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@@ -384,6 +384,22 @@ inline raw_ostream &operator<<(raw_ostream &OS, const PathType &Path) {
   return OS;
 }
 
+/// Helper to get the successor corresponding to a particular case value for
+/// a switch statement.
+static BasicBlock *getNextCaseSuccessor(SwitchInst *Switch,
+                                        const APInt &NextState) {
+  BasicBlock *NextCase = nullptr;
+  for (auto Case : Switch->cases()) {
+    if (Case.getCaseValue()->getValue() == NextState) {
+      NextCase = Case.getCaseSuccessor();
+      break;
+    }
+  }
+  if (!NextCase)
+    NextCase = Switch->getDefaultDest();
+  return NextCase;
+}
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nikic wrote:

I realize you only moved this code, but it would probably make sense to compute the value => successor mapping once instead of scanning the whole switch each time.

https://github.com/llvm/llvm-project/pull/162447