SN Systems Tech Blog


Targeting a statically compiled program repository with LLVM

ARTICLE BY: Russell Gallop & Phil Camp
POSTED: Jul 17, 2019
TAGS: LLVM Developers Meeting, Toolchain

Following on from the 2016 talk "Demo of a repository for statically compiled programs", this lightning talk will present a brief overview of how LLVM was modified to target a program repository. This includes adding a new target output format and a new optimization pass to skip program elements already present in the repository.


Analyzing the size of the compiler executable

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

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.


Measuring the User Debug Experience

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

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.