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Rollup merge of #81255 - sunfishcode:wasi-no-export-dynamic, r=alexcrichton

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Don't link with --export-dynamic on wasm32-wasi

Remove --export-dynamic from the link arguments on the wasm32-wasi
target, as it emits spurious exports and increases code size.

Leave it in place for wasm32-unknown-unknown and
wasm32-unknown-emscripten. Even though it isn't a great solution
there, users are likely depending on its behavior there.
This commit is contained in:
Jonas Schievink 2021-01-31 16:36:44 +01:00 • committed by GitHub
commit ed5614599a
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3 changed files with 24 additions and 15 deletions
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9
compiler/rustc_target/src/spec/wasm32_base.rs
View file

@ -55,15 +55,6 @@ pub fn options() -> TargetOptions {
// to do so.
arg("--no-demangle");
// The symbol visibility story is a bit in flux right now with LLD.
// It's... not entirely clear to me what's going on, but this looks to
// make everything work when `export_symbols` isn't otherwise called for
// things like executables.
//
// This is really only here to get things working. If it can be removed and
// basic tests still work, then sounds like it should be removed!
arg("--export-dynamic");
let mut pre_link_args = BTreeMap::new();
pre_link_args.insert(LinkerFlavor::Lld(LldFlavor::Wasm), lld_args);
pre_link_args.insert(LinkerFlavor::Gcc, clang_args);

13
compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs
View file

@ -2,6 +2,17 @@ use super::wasm32_base;
use super::{LinkArgs, LinkerFlavor, PanicStrategy, Target, TargetOptions};
pub fn target() -> Target {
let mut options = wasm32_base::options();
let clang_args = options.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap();
// Rust really needs a way for users to specify exports and imports in
// the source code. --export-dynamic isn't the right tool for this job,
// however it does have the side effect of automatically exporting a lot
// of symbols, which approximates what people want when compiling for
// wasm32-unknown-unknown expect, so use it for now.
clang_args.push("--export-dynamic".to_string());
let mut post_link_args = LinkArgs::new();
post_link_args.insert(
LinkerFlavor::Em,
@ -28,7 +39,7 @@ pub fn target() -> Target {
panic_strategy: PanicStrategy::Unwind,
post_link_args,
os_family: Some("unix".to_string()),
..wasm32_base::options()
..options
};
Target {
llvm_target: "wasm32-unknown-emscripten".to_string(),

17
compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
View file

@ -26,11 +26,18 @@ pub fn target() -> Target {
// For now this target just never has an entry symbol no matter the output
// type, so unconditionally pass this.
clang_args.push("-Wl,--no-entry".to_string());
options
.pre_link_args
.get_mut(&LinkerFlavor::Lld(LldFlavor::Wasm))
.unwrap()
.push("--no-entry".to_string());
// Rust really needs a way for users to specify exports and imports in
// the source code. --export-dynamic isn't the right tool for this job,
// however it does have the side effect of automatically exporting a lot
// of symbols, which approximates what people want when compiling for
// wasm32-unknown-unknown expect, so use it for now.
clang_args.push("-Wl,--export-dynamic".to_string());
// Add the flags to wasm-ld's args too.
let lld_args = options.pre_link_args.get_mut(&LinkerFlavor::Lld(LldFlavor::Wasm)).unwrap();
lld_args.push("--no-entry".to_string());
lld_args.push("--export-dynamic".to_string());
Target {
llvm_target: "wasm32-unknown-unknown".to_string(),