Refined Input, Degraded Output: The Counterintuitive World of Compiler Behavior
The study delves into compiler behavior when given extra information for program optimization. Surprisingly, more data can sometimes lead to poorer optimization due to intricate compiler interactions. Testing identified 59 cases in popular compilers, emphasizing the need for better understanding.
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The article "Refined Input, Degraded Output: The Counterintuitive World of Compiler Behavior" explores the impact of providing additional information to compilers on program optimization. Contrary to the common belief that more information leads to better optimization, the study reveals that in some cases, extra information can actually result in worse optimization due to unexpected interactions between compiler components. The research focuses on two types of information: dead code and value ranges. By refining seed programs with extra information, the study developed a testing method to identify instances where optimization deteriorates. The evaluation found 59 cases in widely used compilers like GCC and LLVM, with 55 cases confirmed or resolved. This work sheds light on the complexities of compiler behavior and emphasizes the need for a deeper understanding to enhance compiler performance.
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2 commentsAs a vaguely related similar idea, once upon a time at a hardware company we had a regression suite that failed if our chip was less performant than a competitor’s. But that test suite was largely hand crafted. The ability to generate these cases randomly is super cool.
It even git bisects to the commit introducing a regression
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