[llvm] [Bitcode] Fix incomplete deduplication of PHI entries (PR #162860)

[Nikita Popov via llvm-commits]

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@@ -658,6 +658,26 @@ void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
   this->replaceSuccessorsPhiUsesWith(this, New);
 }
 
+void BasicBlock::deduplicatePhiUsesOf(BasicBlock *BB) {
+  // N.B. This might not be a complete BasicBlock, so don't assume
+  // that it ends with a non-phi instruction.
+  for (Instruction &I : *this) {
+    PHINode *PN = dyn_cast<PHINode>(&I);
+    if (!PN)
+      break;
+    // Since the order of basic blocks in a PHINode are sorted we can
+    // use the index of \p BB + 1 as the first index to check for duplicates.
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nikic wrote:

The blocks are generally not sorted.

https://github.com/llvm/llvm-project/pull/162860