Description
I noticed that the size of rustc_driver.dll for the windows x86_64-pc-windows-gnu toolchain seems suprisingly large compared to the x86-64-pc-windows-msvc toolchain. It's also been growing quickly in recent releases.
See chart below comparing the size of rustc_driver.dll for these two targets for stable releases since 1.40:
Some size difference is obviously expected, however the huge jump around Rust 1.54 (slightly over doubling of the file size) looks suspect.
Bisecting on nightlies around that time, it looks like the jump happened in nightly 2021-06-05:
| nightly | x86_64-pc-windows-gnu rustc_driver size (bytes) |
|---|---|
| 2021-06-03 | 199015985 |
| 2021-06-04 | 199027556 |
| 2021-06-05 | 442938696 |
| 2021-06-06 | 442876820 |
I've recently been working in an environment where the file size matters. I don't know much about the compiler packaging process, however I'd be happy to help investigate and (if possible) undo this jump in file size, with the help of someone willing to guide me where to look.
So far, I started out by looking at PRs merged on 2021-06-04 (i.e. the day before the size bump).
The only PR that stands out to me as potentially affecting file size is #84449. I am wildly speculating; this could be a red herring. I'm going to investigate this a little further. Input from others more knowledgeable than myself is very welcome!