[PATCH] D131672: [instcombine] Optimise for zero initialisation of product given fast flags are enabled

[Zain Jaffal via Phabricator via llvm-commits]

zjaffal added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp:492
+    if (Constant *StartConst = dyn_cast<Constant>(Start)) {
+      if (StartConst->isZeroValue())
+        return replaceInstUsesWith(I, StartConst);
----------------
spatel wrote:
> Was there a reason to not use the shorter and suggested m_Zero() matcher? 
> It probably doesn't make a difference for this particular pattern, but that code handles things like vector constants, so we won't miss any unusual types.
I didn't know it existed. I will push a change now


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  https://reviews.llvm.org/D131672/new/

https://reviews.llvm.org/D131672