[PATCH] D108049: [InstCombine] Extend canonicalizeClampLike to handle truncated inputs

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

Sorry, this should not be taking so long.



================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:1350-1351
+  if (Cmp00->getType() != X->getType())
+    if (auto *T = dyn_cast<TruncInst>(X))
+      X = T->getOperand(0);
+
----------------
`match(&X, m_TruncOrSelf(m_Value(X)));` ?


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:1427
+  if (X->getType() != Sel0.getType() &&
+      (!isa<Constant>(ReplacementLow) || !isa<Constant>(ReplacementHigh)))
+    return nullptr;
----------------
This accepts constant exprs too. You probably want `m_ImmConstant()` matcher.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:1441
+      MaybeReplacedLow);
+  return Builder.CreateTrunc(MaybeReplacedHigh, Sel0.getType());
 }
----------------
Hm, so this now creates one more instruction than before,
but i'm not seeing one more one-use check being added.
Perhaps the original `trunc` should be one-use?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108049/new/

https://reviews.llvm.org/D108049