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

[Matt Arsenault via Phabricator via llvm-commits]

arsenm 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))
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efriedma wrote:
> 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.
This needs to do something to handle the null block. Can it emit an __unnamed symbol or something like for anonymous functions? If this is going to assert on null the verifier at least has to check it


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  https://reviews.llvm.org/D124697/new/

https://reviews.llvm.org/D124697