[PATCH] D84547: [ConstraintElimination] Add constraint elimination pass.

Sanjay Patel via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Aug 27 08:42:33 PDT 2020


spatel added a reviewer: reames.
spatel added a comment.

I'm not familiar with the underying ConstraintSystem (Fourier–Motzkin elimination), so if anyone else has experience with it and can chime in, that would be nice.

Would the overflow concerns mentioned in the description be handled more easily by changing the ConstraintSystem to use APInt?

Given that this is off-by-default, I don't think this needs detailed review at this stage - we have sufficient optimization motivation, and the cost of keeping it in trunk while making improvements isn't high. Either we'll eventually flip it to default-on because it will be shown to be worth its compile-time cost, or it will be dismissed and removed.



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Comment at: llvm/test/Transforms/ConstraintElimination/uge.ll:2
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S %s | FileCheck %s
+; RUN: opt -instcombine -S %s | FileCheck %s
 
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