[PATCH] D50222: [CodeGen] [SelectionDAG] More efficient code for X % C == 0 (UREM case)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: lib/CodeGen/SelectionDAG/TargetLowering.cpp:3727
+                                        const SDLoc &DL) const {
+  // fold (seteq/ne (urem N, D), 0) -> (setule/gte (rotr (mul N, P), K), Q)
+  // - D must be constant with D = D0 * 2^K where D0 is odd
----------------
lebedev.ri wrote:
> lebedev.ri wrote:
> > ```
> > assert((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
> >        "Only applicable for [in]equality comparisons.");
> > ```
> ```
> // fold (seteq/ne (urem N, D), 0) -> (setule/ugt (rotr (mul N, P), K), Q)
> 
> ```
> (it would be great to use more descriptive names to differentiate between `C`onstants and not constants, too)
> (it would be great to use more descriptive names to differentiate between Constants and not constants, too)

But thinking about it a bit more, probably don't rename the variables. Consistency [with the orig doc] may be best.


Repository:
  rL LLVM

https://reviews.llvm.org/D50222