[PATCH] D75755: [AArch64][Fix] LdSt optimization generate premature stack-popping

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

I think there's a secondary problem here: if we move an SP adjustment, we might also need to adjust the unwind/debug info.  This is particularly nasty on Windows, where messing up the unwind info can actually cause a miscompile.

If you don't want to spend the time to try to figure that out, I'd be happy to just completely forbid optimizing sp adjustments here.  It should be rare enough that it doesn't matter much in practice.



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Comment at: llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp:1832
+        }
+        if (PSVa->mayAlias(MFI)){
+          MayAliasFP = true;
----------------
I'm not sure what you think this mayAlias check is doing?


Repository:
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  https://reviews.llvm.org/D75755/new/

https://reviews.llvm.org/D75755