[PATCH] D39954: [IRCE] Smart range intersection

[Anna Thomas via Phabricator via llvm-commits]

anna added a comment.

Max, the patch explanation and logic of using SCEV subtraction LGTM. I'll need to take a closer look at your rules and the calculation in subtraction lambda.



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Comment at: lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp:1658
+           "We can only substract from values in [0; SINT_MAX]!");
+    if (IsLatchSigned) {
+      // X is a number from signed range, Y is interpreted as signed.
----------------
To clarify: In both cases - signed and unsigned latch, the SCEV subtraction and rules you have below will always give us a value in range [0, SINT_MAX], i.e. we will never cross the signed border.
Here we are just "strengthening" the range and using unambiguous values for range intersection later on IRCE. 


https://reviews.llvm.org/D39954