[PATCH] D115904: [DSE] Remove calls with known writes to dead memory

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/include/llvm/Analysis/MemoryLocation.h:260
+  /// sunk, reordered, etc... solely based on the memory semantics implied by
+  /// the described write, and the def-use chain of the result value (if any).
   static Optional<MemoryLocation> getForDest(const CallBase *CI,
----------------
This might want to highlight that the function can still read other memory.


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Comment at: llvm/lib/Analysis/MemoryLocation.cpp:154
+  // that we can so summarize.
+  if (!CB->onlyAccessesArgMemory() || !CB->willReturn() || !CB->doesNotThrow())
+    return None;
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I'm not sure the willreturn and nounwind checks really belong in here. We should try to separate the modelling of different effects, and MemoryLocation should only be modelling memory effects. The willreturn/nounwind checks can be done in the caller.

After all, the statement that only this one location is written remains true regardless of whether the call unwind or diverge, the latter only affect whether it can be removed.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115904/new/

https://reviews.llvm.org/D115904