> LTO was available in llvm forever, and well predates GCC, clang is just a particular frontend.
For the initial version of this guide, I chose to focus on features as they are exposed in specific tools, as it's easier to pin down a "first available" date that way. Basic LTO for Clang is listed as first available in Clang 2.6, which is also the first LLVM release to officially include Clang.
> It also misses the function summary vs non summary modes, which is fairly important.
Are you talking about the module summaries LLVM uses in its parallel / thin LTO mode, or something else?
LTO was available in llvm forever, and well predates GCC, clang is just a particular frontend.
RMS finally allowed the GCC IR to be saved to disk in part as a response to llvm doing it and becoming popular
(I worked on both GCC and llvm forever)
It also misses the function summary vs non summary modes, which is fairly important.