[PATCH] D76010: [ValueTracking] Let isGuaranteedNotToBeUndefOrPoison look into more constants/instructions

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added inline comments.


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Comment at: llvm/lib/Analysis/ValueTracking.cpp:4548
+  // Call stripPointerCastsSameRepresentation to take addrspacecast out of
+  // consideration.
+  auto *StrippedV = V->stripPointerCastsSameRepresentation();
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This is not 100% the idea behind `stripPointerCastsSameRepresentation`:
`stripPointerCastsSameRepresentation` says the bit-representation stays the same, not that there are no addrspacecasts stripped. If we assume an addressspacecast that is known not to modify the bit-representation will also not modify the poison/undef state, which I think is reasonable, we can do tihs.


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Comment at: llvm/lib/Analysis/ValueTracking.cpp:4553
+    // gep inbounds null, 0 is also null.
     return true;
 
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misplaced comment


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  https://reviews.llvm.org/D76010/new/

https://reviews.llvm.org/D76010