I have seen move semantics applied to constructors, but in this bit of code, I'm wondering if the big struct is copied entirely when returned or not. I'm not even sure it is related to move semantics. Does C++ always copies this kind of data, or is it optimized? Could...
Here is my code: If I compile this with O0 option, g++ -O0 main.cpp -o main, the result is 1. If I compile with O2 option, g++ -O2 main.cpp -o main, this will give a result of 0.
With Java instruction reordering the execution order of the code is changed by the JVM at compile time or run time, possibly causing unrelated statements to be executed out-of-order.
With most C/C++ compilers, there's a flag passable to the compiler, -march=native, which tells the compiler to tune generated code for the micro-architecture and ISA extensions of the host CPU. Even if it doesn't go by the same name, there's typically an equivalent option for LLVM-based compilers, like rustc or...
Fully knowing that these completely artificial benchmarks don't mean much, I am nonetheless a bit surprised by the several ways the "big 4" compilers chose to compile a trivial snippet.
I finished a small Rust project (about 300 lines of code) with the following dependencies:When using cargo build --release without further configuration, a 2.942.744 bytes (= 2,8 MiB) binary is generated. I tried to optimize this by enabling Link Time Optimization (LTO) in my Cargo.toml:
I have a Main method like this:Since I am accessing a local variable b here the compiler creates a class to capture that variable and b becomes the field of that class. Then the b lives as long as the life time of the compiler generated class and it causes...
While writing a function using iterate in Haskell, I found that an equivalent version with explicit recursion seemed noticeably faster - even though I believed that explicit recursion ought to be frowned upon in Haskell.
Most popular example to illustrate why virtual dispatch happens at runtime is when it cannot be determined at compile time which Derived class is going to be created. For example:
I have a very weird compiler behavior where G++ pulls computations into a hot loop, severly reducing the performance of the resulting code. What is going on here?