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Rollup merge of #133297 - DianQK:embed-bitcode-ios, r=nikic

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Remove legacy bitcode for iOS

Follow #117364.
This commit is contained in:
许杰友 Jieyou Xu (Joe) 2024-11-25 00:39:05 +08:00 committed by GitHub
commit 8d20d71256
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4 changed files with 8 additions and 35 deletions
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19
compiler/rustc_codegen_llvm/src/back/write.rs
View File

@ -955,24 +955,7 @@ pub(crate) fn bitcode_section_name(cgcx: &CodegenContext<LlvmCodegenBackend>) ->
}
}
/// Embed the bitcode of an LLVM module in the LLVM module itself.
///
/// This is done primarily for iOS where it appears to be standard to compile C
/// code at least with `-fembed-bitcode` which creates two sections in the
/// executable:
///
/// * __LLVM,__bitcode
/// * __LLVM,__cmdline
///
/// It appears *both* of these sections are necessary to get the linker to
/// recognize what's going on. A suitable cmdline value is taken from the
/// target spec.
///
/// Furthermore debug/O1 builds don't actually embed bitcode but rather just
/// embed an empty section.
///
/// Basically all of this is us attempting to follow in the footsteps of clang
/// on iOS. See #35968 for lots more info.
/// Embed the bitcode of an LLVM module for LTO in the LLVM module itself.
unsafe fn embed_bitcode(
cgcx: &CodegenContext<LlvmCodegenBackend>,
llcx: &llvm::Context,

6
compiler/rustc_codegen_ssa/src/back/write.rs
View File

@ -432,11 +432,9 @@ struct CompiledModules {
fn need_bitcode_in_object(tcx: TyCtxt<'_>) -> bool {
let sess = tcx.sess;
let requested_for_rlib = sess.opts.cg.embed_bitcode
sess.opts.cg.embed_bitcode
&& tcx.crate_types().contains(&CrateType::Rlib)
&& sess.opts.output_types.contains_key(&OutputType::Exe);
let forced_by_target = sess.target.forces_embed_bitcode;
requested_for_rlib || forced_by_target
&& sess.opts.output_types.contains_key(&OutputType::Exe)
}
fn need_pre_lto_bitcode_for_incr_comp(sess: &Session) -> bool {

5
compiler/rustc_target/src/spec/mod.rs
View File

@ -2327,8 +2327,6 @@ pub struct TargetOptions {
/// If we give emcc .o files that are actually .bc files it
/// will 'just work'.
pub obj_is_bitcode: bool,
/// Whether the target requires that emitted object code includes bitcode.
pub forces_embed_bitcode: bool,
/// Content of the LLVM cmdline section associated with embedded bitcode.
pub bitcode_llvm_cmdline: StaticCow<str>,
@ -2671,7 +2669,6 @@ impl Default for TargetOptions {
allow_asm: true,
has_thread_local: false,
obj_is_bitcode: false,
forces_embed_bitcode: false,
bitcode_llvm_cmdline: "".into(),
min_atomic_width: None,
max_atomic_width: None,
@ -3412,7 +3409,6 @@ impl Target {
key!(main_needs_argc_argv, bool);
key!(has_thread_local, bool);
key!(obj_is_bitcode, bool);
key!(forces_embed_bitcode, bool);
key!(bitcode_llvm_cmdline);
key!(max_atomic_width, Option<u64>);
key!(min_atomic_width, Option<u64>);
@ -3687,7 +3683,6 @@ impl ToJson for Target {
target_option_val!(main_needs_argc_argv);
target_option_val!(has_thread_local);
target_option_val!(obj_is_bitcode);
target_option_val!(forces_embed_bitcode);
target_option_val!(bitcode_llvm_cmdline);
target_option_val!(min_atomic_width);
target_option_val!(max_atomic_width);

13
src/doc/rustc/src/codegen-options/index.md
View File

@ -119,17 +119,14 @@ files. It takes one of the following values:
* `n`, `no`, `off` or `false`: omit bitcode from rlibs.
LLVM bitcode is required when rustc is performing link-time optimization (LTO).
It is also required on some targets like iOS ones where vendors look for LLVM
bitcode. Embedded bitcode will appear in rustc-generated object files inside of
a section whose name is defined by the target platform. Most of the time this is
`.llvmbc`.
Embedded bitcode will appear in rustc-generated object files inside of a section
whose name is defined by the target platform. Most of the time this is `.llvmbc`.
The use of `-C embed-bitcode=no` can significantly improve compile times and
reduce generated file sizes if your compilation does not actually need bitcode
(e.g. if you're not compiling for iOS or you're not performing LTO). For these
reasons, Cargo uses `-C embed-bitcode=no` whenever possible. Likewise, if you
are building directly with `rustc` we recommend using `-C embed-bitcode=no`
whenever you are not using LTO.
(e.g. if you're not performing LTO). For these reasons, Cargo uses `-C embed-bitcode=no`
whenever possible. Likewise, if you are building directly with `rustc` we recommend
using `-C embed-bitcode=no` whenever you are not using LTO.
If combined with `-C lto`, `-C embed-bitcode=no` will cause `rustc` to abort
at start-up, because the combination is invalid.