What Every Programmer Should Know About Compiler Optimizations

High level programming languages ​​have many abstract programming constructs like functions, conditional statements and loops that make us very productive. However, one of the disadvantages of writing code in a high-level language is the possibility of a significant decrease in program speed.

Today, optimization logic has become very complex: compilers modify loops, conditions, and recursive functions; Remove entire blocks of code. They optimised the code architecture of the processor to be fast and compact. Also, manual optimizations prevent the compiler from performing more and more efficient automatic optimizations.

Instead of writing optimizations by hand, it’s better to focus on architectural design and efficient algorithms, including parallelism and the use of library functions. Back-end developer work is very important to optimise compilers. You need to hire backend developer who is well versed in this topic.

Definition Of Optimizations Compilers

Optimization is the process of converting one piece of code into another piece equivalent to the original in order to improve one or more of its features, the most important of which is the speed and size of the code.

Other characteristics include the amount of power used to run the code and the compilation time (and the JIT compilation time if the resulting code uses JIT).

Compilers are constantly evolving, and the methods they use are also evolving. Even if not perfect, often the best approach is to stick to low-level compiler optimization instead of trying it manually.

Link-Time Code Generation

Link-Time Code Generation (LTCG) is a technique for performing full program optimizations (WPO) on C/C++ code. The C/C++ compiler processes each source code file separately and creates the corresponding object file. In other words, the compiler can only optimize a single file instead of optimising the entire program.

However, some important optimizations can only be applied to the entire program. You can only use these optimizations at link time, not at compile time, since the linker is fully program-aware.

Debug Configuration

Debug configuration is primarily used because if you specify the /od switch without the /GL switch, all core optimizations will be disabled. In this configuration, the resulting object files have binary code that exactly matches the source code.

You can view the assembler output files and the resulting mapping file to see for yourself. The setting corresponds to the debug setting in Visual Studio.

Compile-Time Code Generation Release Configuration

This setting is similar to the version setting (which specifies /O1, /O2, or /Ox), but does not include the /GL switch. In this configuration, the resulting object files contain the optimized binary, but no program-wide optimizations are performed.

Optimizations In .NET

No .NET linker is included in the build model. However, there is a source code compiler (C# compiler) and a JIT compiler. Very few optimizations were made to the source code. For example, at this level you won’t see any inline or loop optimization for functions. However, these optimizations are performed at the JIT level. The JIT compiler prior to .NET 4.5 did not support SIMD. But the JIT compiler since .NET 4.5.1 (called RyuJIT) does support SIMD.

All of the optimization techniques discussed in this article can improve the performance of your code by a double digit percentage. All this is supported by the Visual C ++ compiler. What makes these techniques important is that once used, the compiler can perform further optimization. This article is not a complete discussion of all the optimizations performed in Visual C ++. However, I hope you are now happy with the Collector’s capabilities. Visual C ++ can do much, much more. We’ll talk more about this here.