Remove bitcode_llvm_cmdline

It used to be necessary on Apple platforms to ship with the App Store,
but XCode 15 has stopped embedding LLVM bitcode and the App Store no
longer accepts apps with bitcode embedded.

Author: bjorn3

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -862,7 +862,7 @@ pub(crate) fn codegen(
                     .generic_activity_with_arg("LLVM_module_codegen_embed_bitcode", &*module.name);
                 let thin_bc =
                     module.thin_lto_buffer.as_deref().expect("cannot find embedded bitcode");
-                embed_bitcode(cgcx, llcx, llmod, &config.bc_cmdline, &thin_bc);
+                embed_bitcode(cgcx, llcx, llmod, &thin_bc);
             }
         }
 
@@ -1058,7 +1058,6 @@ fn embed_bitcode(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     llcx: &llvm::Context,
     llmod: &llvm::Module,
-    cmdline: &str,
     bitcode: &[u8],
 ) {
     // We're adding custom sections to the output object file, but we definitely
@@ -1074,7 +1073,9 @@ fn embed_bitcode(
     // * Mach-O - this is for macOS. Inspecting the source code for the native
     //   linker here shows that the `.llvmbc` and `.llvmcmd` sections are
     //   automatically skipped by the linker. In that case there's nothing extra
-    //   that we need to do here.
+    //   that we need to do here. We do need to make sure that the
+    //   `__LLVM,__cmdline` section exists even though it is empty as otherwise
+    //   ld64 rejects the object file.
     //
     // * Wasm - the native LLD linker is hard-coded to skip `.llvmbc` and
     //   `.llvmcmd` sections, so there's nothing extra we need to do.
@@ -1111,7 +1112,7 @@ fn embed_bitcode(
         llvm::set_linkage(llglobal, llvm::Linkage::PrivateLinkage);
         llvm::LLVMSetGlobalConstant(llglobal, llvm::True);
 
-        let llconst = common::bytes_in_context(llcx, cmdline.as_bytes());
+        let llconst = common::bytes_in_context(llcx, &[]);
         let llglobal = llvm::add_global(llmod, common::val_ty(llconst), c"rustc.embedded.cmdline");
         llvm::set_initializer(llglobal, llconst);
         let section = if cgcx.target_is_like_darwin {
@@ -1128,7 +1129,7 @@ fn embed_bitcode(
         let section_flags = if cgcx.is_pe_coff { "n" } else { "e" };
         let asm = create_section_with_flags_asm(".llvmbc", section_flags, bitcode);
         llvm::append_module_inline_asm(llmod, &asm);
-        let asm = create_section_with_flags_asm(".llvmcmd", section_flags, cmdline.as_bytes());
+        let asm = create_section_with_flags_asm(".llvmcmd", section_flags, &[]);
         llvm::append_module_inline_asm(llmod, &asm);
     }
 }

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -99,7 +99,6 @@ pub struct ModuleConfig {
     pub emit_obj: EmitObj,
     pub emit_thin_lto: bool,
     pub emit_thin_lto_summary: bool,
-    pub bc_cmdline: String,
 
     // Miscellaneous flags. These are mostly copied from command-line
     // options.
@@ -216,7 +215,6 @@ impl ModuleConfig {
                 sess.opts.output_types.contains_key(&OutputType::ThinLinkBitcode),
                 false
             ),
-            bc_cmdline: sess.target.bitcode_llvm_cmdline.to_string(),
 
             verify_llvm_ir: sess.verify_llvm_ir(),
             lint_llvm_ir: sess.opts.unstable_opts.lint_llvm_ir,

compiler/rustc_target/src/spec/json.rs

@@ -167,7 +167,6 @@ impl Target {
         forward!(main_needs_argc_argv);
         forward!(has_thread_local);
         forward!(obj_is_bitcode);
-        forward!(bitcode_llvm_cmdline);
         forward_opt!(max_atomic_width);
         forward_opt!(min_atomic_width);
         forward!(atomic_cas);
@@ -359,7 +358,6 @@ 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!(bitcode_llvm_cmdline);
         target_option_val!(min_atomic_width);
         target_option_val!(max_atomic_width);
         target_option_val!(atomic_cas);
@@ -552,7 +550,6 @@ struct TargetSpecJson {
     main_needs_argc_argv: Option<bool>,
     has_thread_local: Option<bool>,
     obj_is_bitcode: Option<bool>,
-    bitcode_llvm_cmdline: Option<StaticCow<str>>,
     max_atomic_width: Option<u64>,
     min_atomic_width: Option<u64>,
     atomic_cas: Option<bool>,

compiler/rustc_target/src/spec/mod.rs

@@ -2620,8 +2620,6 @@ pub struct TargetOptions {
     /// If we give emcc .o files that are actually .bc files it
     /// will 'just work'.
     pub obj_is_bitcode: bool,
-    /// Content of the LLVM cmdline section associated with embedded bitcode.
-    pub bitcode_llvm_cmdline: StaticCow<str>,
 
     /// Don't use this field; instead use the `.min_atomic_width()` method.
     pub min_atomic_width: Option<u64>,
@@ -2984,7 +2982,6 @@ impl Default for TargetOptions {
             allow_asm: true,
             has_thread_local: false,
             obj_is_bitcode: false,
-            bitcode_llvm_cmdline: "".into(),
             min_atomic_width: None,
             max_atomic_width: None,
             atomic_cas: true,