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Analyzing the size of the compiler executable

ARTICLE BY: Russell Gallop
POSTED: Jul 17, 2019
TAGS: 2019 European LLVM Developers Meeting, Compiler

The title of this lighting talk is from a bug filed in the early days of the PS4 compiler. It noted that the LLVM-based PS4 compiler was more than 3 times larger than the PS3 compiler. Since then it has almost doubled to over 40MB. For a compiler which targets one system this seems excessive. Executable size can cost in worse cache performance and cost time if transferring for distributed builds.

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Measuring the User Debug Experience

ARTICLE BY: Greg Bedwell
POSTED: Jul 11, 2019
TAGS: Compiler, Debugger, LLVM

For a game to hit 30 frames-per-second, all of the frame compute has to fit into ~33.3 ms, at 60 frames-per-second it has to fit into ~16.7 ms. Games are reliant on compiler optimizations to get near to these target frame times, without these optimizations the game may be unplayable. Unfortunately, compiler optimizations tend to interfere with the "debuggability" of the code. This can be for legitimate reasons, i.e. some optimizations fundamentally changing the structure of the code and it may no longer resemble the original source code. In other cases, it can be down to the compiler not preserving debug information that could have been preserved. Game developers often need to play the fully optimized game in order to trigger the required condition to reproduce a reported bug. Making it easier to debug fully optimized code is a request that we hear regularly from game developers.

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Understanding the performance of code using LLVM's (llvm-mca)

ARTICLE BY: Andrea Di Biagio
POSTED: Dec 13, 2018
TAGS: Compiler, LLVM, Toolchain

LLVM-mca is a LLVM based tool that uses information available in LLVM’s scheduling models to statically measure the performance of machine code in a specific CPU. The goal of this tool is not just to predict the performance of the code when run on the target, but also to help with diagnosing potential performance issues. In this talk we, will discuss how llvm-mca works and walk the audience through example uses of this tool.

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