[PATCH] D108201: [AggressiveInstCombine] Add logical shift right instr to `TruncInstCombine` DAG

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev marked 2 inline comments as done.
anton-afanasyev added inline comments.


================
Comment at: llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp:297-298
+        KnownBits KnownLHS = computeKnownBits(I->getOperand(0), DL);
+        MinBitWidth =
+            std::max(MinBitWidth, KnownLHS.getMaxValue().getActiveBits());
+        if (MinBitWidth >= OrigBitWidth)
----------------
spatel wrote:
> We already returned if MinBitWdith based on KnownRHS was too big, so this std::max is redundant?
No, it isn't: we still use this updated MinBitWidth by setting it to instruction Info:
```
Itr.second.MinBitWidth = MinBitWidth;
```
This value is then used while computing common MinBitWidth in getMinBitWidth() function.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108201/new/

https://reviews.llvm.org/D108201