[PATCH] D91343: [InstCombine] Optimize away the unnecessary multi-use sign-extend

[Jeroen Dobbelaere via Phabricator via llvm-commits]

jeroen.dobbelaere added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp:922-925
+    // If this user is only demanding bits that we know, return the known
+    // constant.
+    if (DemandedMask.isSubsetOf(Known.Zero | Known.One))
+      return Constant::getIntegerValue(ITy, Known.One);
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Maybe this should be moved between line 904 and 906 ? (After the computKnownBits, but before checking the signextend pattern). This brings it more in line how the other cases are handled, preferring to return a constant when that is possible.



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  https://reviews.llvm.org/D91343/new/

https://reviews.llvm.org/D91343