[PATCH] D109515: [AggressiveInstCombine] Add `udiv` and `urem` instrs to TruncInstCombine DAG

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev added inline comments.


================
Comment at: llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp:318-319
+        KnownBits Known = computeKnownBits(Op);
+        MinBitWidth =
+            std::max(Known.getMaxValue().getActiveBits(), MinBitWidth);
+        if (MinBitWidth >= OrigBitWidth)
----------------
lebedev.ri wrote:
> Hm, if you swap arguments around, does it lead to better clang-format?
No(
It fixes even my "legal" trials like this one:
```
        MinBitWidth = std::max(Known.getMaxValue().getActiveBits(),
                               MinBitWidth);
```


================
Comment at: llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp:151
+      // 2. phi node(and loop handling)
       // ...
       return false;
----------------
lebedev.ri wrote:
> sdiv, srem; see b289dc530632613edb3eb067895c1981cb77ccd0.
Ok, added to todo.


================
Comment at: llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp:314-323
+      KnownBits KnownLHS = computeKnownBits(I->getOperand(0));
+      unsigned MinBitWidth = KnownLHS.getMaxValue().getActiveBits();
+      if (MinBitWidth >= OrigBitWidth)
+        return nullptr;
+      KnownBits KnownRHS = computeKnownBits(I->getOperand(1));
+      MinBitWidth =
+          std::max(MinBitWidth, KnownRHS.getMaxValue().getActiveBits());
----------------
lebedev.ri wrote:
> 
Ok, done.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D109515/new/

https://reviews.llvm.org/D109515