SV2 | Support Vector Structural Variation Genotyper | Genomics library

Not sure if I understand the goal.

Do you want this?

Here is the code that does this:

For a while I was looking for a similar problem in reviews of popular live wallpapers. I found similar reviews only for one application. I updated my phone today. All my live wallpapers stopped working as expected. Then I installed "Earth & Moon" and this app works fine. It means that we are doing something wrong or, on the contrary, we are not doing something :) In the near future I will begin to investigate this problem.

It's interesting that it points to .dart_tool/flutter_gen/pubspec.yaml. This issue mentions this problem when generate: true is set in the pubspec.yaml.

If you don't need that, try removing it. Also, a flutter clean and flutter pub get might be necessary.

TL;DR: The problem mainly comes from the constant loop bound and not directly from Eigen. Indeed, in the first case, Eigen store the size of the vectors in vector attributes while in the second case, you explicitly use the constant N.

Clever compilers can use this information to unroll loops more aggressively because they know that N is quite big. Unrolling a loop with a small N is a bad idea since the code will be bigger and has to read by the processor. If the code is not already loaded in the L1 cache, it must be loaded from the other caches, the RAM or even the storage device in the worst case. The added latency is often bigger than executing a sequential loop with a small unroll factor. This is why compilers do not always unroll loops (at least not with a big unroll factor).

Inlining also plays an important role in this code. Indeed, if the functions are inlined, the compiler can propagate constants and know the size of the vector enabling it to further optimize the code by unrolling the loop more aggressively. However, if the functions are not inlined, then there is no way the compiler can know the loop bounds. Clever compilers can still generate conditional algorithm to optimize both small loops and big ones but this makes the program bigger and introduces a small overhead. Compilers like ICC and Clang do generate the different code alternatives when the code can be vectorized but the loop bounds are unknown or also when aliasing is not known at compile time (the number of generated variants can quickly be huge and so the code size).

Note that inlining functions may not be enough since the constant propagation can be trapped by a complex conditionals dealing with runtime-defined variables or non-inlined function calls. Alternatively, the quality of the constant propagation may not be sufficient for the target example.

Finally, aliasing also play a critical role in the ability of compilers to generate SIMD instructions (and possibly better unroll the loop) in this code. Indeed, aliasing often prevent the use of SIMD instructions and it is not always easy for compilers to check aliasing and generate fast implementations accordingly.

If the vector-based implementation use a loop bound stored in the vector objects, then the code generated by MSVC is not vectorized in the benchmark: the constant is not propagated correctly despite the inlining of the function. The resulting code should be much slower. Here is the generated code:

This is a bug in clang's diagnosis. The use of curly braces in your last two cases does not 'fix' the dangling pointer issue.

By way of 'confirmation', the Code Analysis tool (static analyser) in Visual Studio/MSVC gives the following warnings for all five svX variables:

Well... given that trim_left() doesn't change data, I suppose that you can write the main trim_left() receiving a T const &

Maybe something like the following?

To change the size from right to left, you have to move the whole page with direction: rtl; Adjust it.

As per the method docs, split_whitespace returns std::str::SplitWhitespace, which is An iterator over the non-whitespace substrings of a string, separated by any amount of whitespace. which means it can split on multiple whitespaces, and doesn't include empty string in the result.

While for split method, Contiguous separators are separated by the empty string. as well as Separators at the start or end of a string are neighbored by empty strings.

So in your example, split_whitespace gives ["a"] but split gives ["a", ""].