Comment by solarexplorer

Yes, I think the conclusion was that it did improve performance on binaries that were not compiled with optimizations, but didn't generate enough gains on optimized binaries to set of the cost of re-compilation.

https://dl.acm.org/doi/10.1145/358438.349303

(this is not about x86 but PA-RISC, but the conclusions would likely be very similar...)