[PATCH] D19338: New code hoisting pass based on GVN (optimistic approach)

[LuoYuanke via Phabricator via llvm-commits]

LuoYuanke added inline comments.
Herald added subscribers: mgrang, mgorny.
Herald added a project: LLVM.


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Comment at: llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp:285
+        // Stop gathering blocks when it is not possible to hoist.
+        if (hasEH(*I))
+          return false;
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Hi,

I'm trying to understanding why we can hoist instruction across exception handler. Is it because the instruction may raise exception and exception pointer should not be changed? Does this hoist rule on exception handler also apply to PRE?

I watch the video that you present, but still didn't figure it out.

Thanks


Repository:
  rL LLVM

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  https://reviews.llvm.org/D19338/new/

https://reviews.llvm.org/D19338