Enable LLVM zlib #72696
Enable LLVM zlib #72696
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src/bootstrap/native.rs
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| @@ -175,6 +174,12 @@ impl Step for Llvm { | |||
| } | |||
| } | |||
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| if builder.config.lld_enabled { | |||
| cfg.define("LLVM_ENABLE_ZLIB", "ON"); | |||
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It's not clear to me if this setting has repercussions beyond LLD.
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Can you think of a reason we wouldn't want to support zlib even if lld isn't enabled? I imagine it's more broadly useful and not measurably slower to compile.
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I looked at the git history and couldn't find a reason for it being off. It may just have been a case of "we don't use it, so why enabled it?"
src/bootstrap/native.rs
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| @@ -175,6 +174,12 @@ impl Step for Llvm { | |||
| } | |||
| } | |||
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| if builder.config.lld_enabled { | |||
| cfg.define("LLVM_ENABLE_ZLIB", "ON"); | |||
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Can you think of a reason we wouldn't want to support zlib even if lld isn't enabled? I imagine it's more broadly useful and not measurably slower to compile.
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@bors r+ |
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📌 Commit 8541213c95ef77bd91f73c75771652710940fc9d has been approved by |
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@bors r+ I think we raced there :) |
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📌 Commit 44b5f53 has been approved by |
…acrum Enable LLVM zlib Compilers may generate ELF objects with compressed sections (although rustc currently doesn't do this). Currently, when linking these with `rust-lld`, you'll get this error: `rust-lld: error: ...: contains a compressed section, but zlib is not available` This enables zlib when building LLVM.
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I think this is responsible for the failure in #72809 (comment) |
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@bors rollup=never |
Out of curiosity, can you elaborate a bit further on this? How can a program compiled with EDIT: this is from the SGX toolchain I guess, but can you elaborate on which parts of it that end up generating compressed sections? |
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You're right the Rust compiler doesn't do this. But C compilers do, for example I believe GCC does this by default on Ubuntu 18.04. So if you're trying to link native code and you're using |
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Who is the NetBSD maintainer? @gandro ? How would we install zlib in the NetBSD build container? |
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cc @MartinHusemann @jakllsch @bgermann @Niacat since you had a NetBSD PR somewhat recently |
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I do not think the problem is that zlib is not installed. The check for the header says: "Looking for zlib.h - found". Maybe it is a missing -lz linker flag. |
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rust maintainer for NetBSD is @he32. i'm responsible for repackaging rust binary releases, however. zlib is part of the NetBSD base system so you shouldn't need to install anything. instead the problem seems to be that the -lz linker flag is missing. semi-relatedly from a NetBSD packaging point of view I'm wondering why rust binaries for NetBSD aren't linked statically, or at a minimum with --static-libstdc++ |
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So which libraries need to be linked is determined by @Niacat Looks like NetBSD is actually specifically excluded from statically linking libstdc++. Although there's some other netbsd-specific stuff at https://github.com/rust-lang/rust/blob/master/src/librustc_llvm/build.rs#L270 . |
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@bors r+ |
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📌 Commit 8caa14f has been approved by |
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Uhhm, this is all very cryptic and totally undebuggable (from my POV). To make it possible to file a bug against llvm upstream, what invocation of llvm-config is supposed to output -lz (and why?) |
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It's not LLVM bug. rust/src/librustc_llvm/build.rs Lines 184 to 186 in 0a675c5 |
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To be clear I'm happy to (in the future) accept a PR fixing this and changing things, but I don't want to block progress for fixes to tier-2 platforms that seem non trivial. |
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According to the git history, passing |
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@bors p=1 letting rollup=never PRs flush out |
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☀️ Test successful - checks-azure |
(Rust now has a dynamic library dependence on zlib. (see rust-lang/rust#72696))
(Rust now has a dynamic library dependence on zlib. (see rust-lang/rust#72696))
PR rust-lang#72696 enabled the option LLVM_ENABLE_ZLIB for the LLVM builds. On Haiku, zlib is linked as a shared library. When cross-compiling LLVM, rustbuild should be instructed to explicitly linking to libz.
…ulacrum Disable zlib in LLVM on Haiku PR rust-lang#72696 enabled the option LLVM_ENABLE_ZLIB for the LLVM builds. Like NetBSD and aarch64-apple-darwin (see PR rust-lang#75500), the LLVM build system not explicitly linking to libz on these platforms cause issues. For Haiku, this meant the runtime loader complaining about undefined symbols..
PR rust-lang#72696 enabled the option LLVM_ENABLE_ZLIB for the LLVM builds. Like NetBSD and aarch64-apple-darwin (see PR rust-lang#75500), the LLVM build system not explicitly linking to libz on these platforms cause issues. For Haiku, this meant the runtime loader complaining about undefined symbols..
@jethrogb I've hit this while futzing around with DragonFly and Solaris builds as well. From what I can tell the issue is that in a cross compiling context (e.g. the NetBSD builds) the host I think it's potentially more appropriate to check for a cross compilation and link to e.g. diff --git a/compiler/rustc_llvm/build.rs b/compiler/rustc_llvm/build.rs
index b0783d75..2bfc421b 100644
--- a/compiler/rustc_llvm/build.rs
+++ b/compiler/rustc_llvm/build.rs
@@ -251,7 +251,7 @@ fn main() {
} else if target.contains("windows-gnu") {
println!("cargo:rustc-link-lib=shell32");
println!("cargo:rustc-link-lib=uuid");
- } else if target.contains("netbsd") || target.contains("haiku") || target.contains("darwin") {
+ } else if is_crossed {
println!("cargo:rustc-link-lib=z");
}
cmd.args(&components); |
Compilers may generate ELF objects with compressed sections (although rustc currently doesn't do this). Currently, when linking these with
rust-lld, you'll get this error:rust-lld: error: ...: contains a compressed section, but zlib is not availableThis enables zlib when building LLVM.