[PATCH] D124697: Distinguish between different forms of "address-taken" MachineBasicBlocks

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


================
Comment at: llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:3481
 
-    // MBBs can have their address taken as part of CodeGen without having
-    // their corresponding BB's address taken in IR
-    if (BB && BB->hasAddressTaken())
-      for (MCSymbol *Sym : getAddrLabelSymbolToEmit(BB))
-        OutStreamer->emitLabel(Sym);
+    assert(BB && BB->hasAddressTaken() && "Missing BB");
+    for (MCSymbol *Sym : getAddrLabelSymbolToEmit(BB))
----------------
arsenm wrote:
> I don't like this hard requirement on the IR. CodeGen passes should try to avoid depending on the block being present (In particular llvm-reduce is now stripping out IR block references).
I'm not sure what alternative you're suggesting here.  There's a contract based on the BasicBlock: we emit a symbol here, and uses of the BlockAddress constant refer to it.  To emit the correct symbol we need the BasicBlock.  If we skip emitting the symbol here, we miscompile.


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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124697/new/

https://reviews.llvm.org/D124697