[PATCH] D35010: [IRCE] Recognize loops with ne/eq latch conditions

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added inline comments.


================
Comment at: lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp:810
+    if (Pred == ICmpInst::ICMP_NE && LatchBrExitIdx == 1)
+      // while (++i != len) {         while (++i < len) {
+      //   ...                 --->     ...
----------------
mkazantsev wrote:
> sanjoy wrote:
> > I don't think this equivalence holds if the RHS is negative.
> What's the problem with negative RHS? There is no conceptual difference between
>   while (++i != 5) ---> while (++i < 5)
> and
>   while (++i != -5) ---> while (++i < -5)
> Maybe what you meant was "if the RHS is less than the IV's initial value"? Such loops get rejected earlier, test_02 exercises this situation. Will add an assert on that.
Actually not earlier, but under this condition we will bail out on line 842.


https://reviews.llvm.org/D35010