[PATCH] D88316: [InstCombine] recognizeBSwapOrBitReverseIdiom - recognise zext(bswap(trunc(x))) patterns (PR39793)

[Sanjay Patel via Phabricator via llvm-commits]

spatel added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/Local.cpp:3027
+  // If the upper bits are zero, then attempt to perform as a truncated op.
+  if (BitProvenance[BitProvenance.size() - 1] < 0) {
+    unsigned NumBits = BitProvenance.size();
----------------
Should this check and the later one be for `== BitPart::Unset` rather than <0?
Can we assert that BitProvenance is not <0 other than Unset?


Repository:
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  https://reviews.llvm.org/D88316/new/

https://reviews.llvm.org/D88316