u/mttdin r/Compilers • Recommends
C++ Switch Statements Under the Hood in LLVM - Hans Wennborg
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Hans Wennborg: C++ switch statements under the hood in LLVM
SwedenCpp
4.8K subscribers • 2 videos on Hallway
- Recommended by 2 people: 2 in engineering communities.
- Presented by Hans Wennborg
Advanced. Deep dive for people who know the field.
4.3K views1 year ago2 recommendations
Systems programmingProgramming languagesCompilers and interpretersC++Performance and optimization
Hans Wennborg explores how Clang and LLVM optimize and compile C++ switch statements into lookup tables, bitmasks, and decision trees.
Are switch statements more efficient than if-else chains? How do they get optimized? This deep dive into Clang/LLVM's handling of the switch construct will tell you everything you wanted to know, and probably more. The event was kindly hosted by think-cell, think-cell.com Event page: meetup.com/stockholmcpp/events/304293099/ More information about C++ in Sweden and around the world at swedencpp.seWhy it's here
2 people recommend thisWhat people say. Recommended as an interesting deep dive into compiler optimizations for switch statements.
u/PeanutHungry5293in r/C_Programming • Recommends
On “Are switch statements faster than if statements?”
Very true! Because of the compiler optimizations like using lookup tables, bitmasking, and BSTs for switch statements, they are relatively faster than if-else statements most of the time.
Also, depending on the compiler optimizations set, it might convert the if-else statements to switch statements if it thinks the switch statement is faster.
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An interesting video explaining a bunch of these compiler optimizations for the switch statement in the LLVM.