[llvm-dev] [ConstantExpr] Adding folding tests

Cameron McInally via llvm-dev llvm-dev at lists.llvm.org
Fri May 3 07:52:42 PDT 2019

On Fri, May 3, 2019 at 10:32 AM Cameron McInally <cameron.mcinally at nyu.edu>

> On Fri, May 3, 2019 at 9:56 AM Tim Northover <t.p.northover at gmail.com>
> wrote:
>> Hi Cameron,
>> On Fri, 3 May 2019 at 14:46, Cameron McInally via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>> > I'd like to add some new constant foldings to ConstantExpr -- in
>> particular ConstantExpr::get(...) and friends. But, I'm having trouble
>> finding the correct place for adding IR tests in the /test directory.
>> test/Analysis/ConstantFolding looks promising. You could also use
> Ah, I should have mentioned that. So Matt and I looked into this, but that
> directory appears to be testing the constant folding in InstructionSimplify
> (and one or two other opt passes). That's a different set of folds.
> Looking closer now, hooking up this instruction (namely FNeg) in
> InstCombine to call ConstantExpr to do the folds is probably the best
> option. There's prior art for this
> in test/Analysis/ConstantFolding/min-max.ll. Does anyone see problems with
> that plan?

Matt was correct from the start. InstructionSimplify ends up calling
ConstantExpr to fold the constants. So the new folds are being exercised

Sorry for the noise! *^_^*
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