[PATCH] D81151: [InstCombine] Simplify compare of Phi with constant inputs against a constant

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev marked an inline comment as done.
mkazantsev added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp:1463
+  if (auto *Phi = dyn_cast<PHINode>(Op0))
+    if (Phi->hasOneUse() &&
+        all_of(Phi->operands(), [](Value *V) { return isa<ConstantInt>(V); })) {
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lebedev.ri wrote:
> I don't think you need one-use check - you produce a single instruction,
> and root icmp from which you started matching always goes away (is replaced by new phi)
Yeah, I wasn't sure if it's ok to change icmp for a phi, but it should be (phis are free if RA makes good job).


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https://reviews.llvm.org/D81151