rustc: Disable ThinLTO for LLVM's build #56890
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This commit goes back to disabling ThinLTO for building LLVM and its tools. It turns out that this caused a regression at rust-lang#56849 which I believe we'll definitely want to fix before it goes live. The bisection turned up an [upstream LLVM bug][bug], so hopefully there'll eventually be a fix we can backport. I've also been a little uneasy about how we're only enabling ThinLTO for LLVM on Linux, and we haven't had a chance to turn it on for OSX and Windows (other "Tier 1" platforms) yet. Additionally it had an unexpected hit to CI time we never got around to fixing. I'd ideally prefer that we fix these issues as well before re-landing. Closes rust-lang#56849 [bug]: https://bugs.llvm.org/show_bug.cgi?id=40045
alexcrichton
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(rust_highfive has picked a reviewer for you, use r? to override) |
rust-highfive
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To double check, this is a bug in the clang 7.0 we use to compile LLVM and does not affect our own use of LLVM (which should have https://reviews.llvm.org/rL339301), right? |
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@nikic correct yeah, and since this is already fixed in LLVM I'm going to submit a different PR to fix this. |
Mark-Simulacrum
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De-beta nominating since we're not planning on landing this. |
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This commit goes back to disabling ThinLTO for building LLVM and its
tools. It turns out that this caused a regression at #56849 which I
believe we'll definitely want to fix before it goes live. The bisection
turned up an upstream LLVM bug, so hopefully there'll eventually
be a fix we can backport.
I've also been a little uneasy about how we're only enabling ThinLTO for
LLVM on Linux, and we haven't had a chance to turn it on for OSX and
Windows (other "Tier 1" platforms) yet. Additionally it had an
unexpected hit to CI time we never got around to fixing. I'd ideally
prefer that we fix these issues as well before re-landing.
Closes #56849