[llvm] [llvm/llvm-project][Coroutines] Improve debugging and minor refactoring (PR #104642)

[Yuxuan Chen via llvm-commits]

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@@ -52,6 +53,16 @@ extern cl::opt<bool> UseNewDbgInfoFormat;
 
 enum { SmallVectorThreshold = 32 };
 
+static std::string getBasicBlockLabel(const BasicBlock *BB) {
+  if (BB->hasName())
+    return BB->getName().str();
+
+  std::string S;
+  raw_string_ostream OS(S);
+  BB->printAsOperand(OS, false);
+  return OS.str().substr(1);
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yuxuanchen1997 wrote:

Under the hood, `printAsOperand` uses `SlotTracker`. (https://github.com/llvm/llvm-project/blob/main/llvm/lib/IR/AsmWriter.cpp#L2599-L2629)

However, it's not entirely clear to me that this slot number will be stable across passes. Looking at the code, it's `printAsOperand` creates the `SlotTracker`. For immediate dumping of the code this may work fine but if you do this again in another pass you may get a different number for the same BB because values can be inserted above. 

https://github.com/llvm/llvm-project/pull/104642