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Diffstat (limited to 'llvm/docs/InstCombineContributorGuide.md')
| -rw-r--r-- | llvm/docs/InstCombineContributorGuide.md | 19 |
1 files changed, 3 insertions, 16 deletions
diff --git a/llvm/docs/InstCombineContributorGuide.md b/llvm/docs/InstCombineContributorGuide.md index cee0a7ce446a..12567fc36f1d 100644 --- a/llvm/docs/InstCombineContributorGuide.md +++ b/llvm/docs/InstCombineContributorGuide.md @@ -96,22 +96,9 @@ may be omitted. If the transform involves commutative operations, add tests with commuted (swapped) operands. -Make sure that the operand order stays intact in the CHECK lines of your -pre-commited tests. You should not see something like this: - -```llvm -; CHECK-NEXT: [[OR:%.*]] = or i8 [[X]], [[Y]] -; ... -%or = or i8 %y, %x -``` - -If this happens, you may need to change one of the operands to have higher -complexity (include the "thwart" comment in that case): - -```llvm -%y2 = mul i8 %y, %y ; thwart complexity-based canonicalization -%or = or i8 %y, %x -``` +As an exception, it is not necessary to test commutation if one of the operands +is a constant: In this case, the constant operand is always canonicalized to +the right. ### Add vector tests |