rustc_codegen_llvm: tease out functions to avoid duplication of bitcode section names

Author: durin42

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -1,4 +1,7 @@
-use crate::back::write::{self, save_temp_bitcode, CodegenDiagnosticsStage, DiagnosticHandlers};
+use crate::back::write::{
+    self, bitcode_section_name, save_temp_bitcode, target_is_aix, target_is_apple,
+    CodegenDiagnosticsStage, DiagnosticHandlers,
+};
 use crate::errors::{
     DynamicLinkingWithLTO, LlvmError, LtoBitcodeFromRlib, LtoDisallowed, LtoDylib,
 };
@@ -121,8 +124,12 @@ fn prepare_lto(
                 .filter(|&(name, _)| looks_like_rust_object_file(name));
             for (name, child) in obj_files {
                 info!("adding bitcode from {}", name);
+                let is_apple = target_is_apple(cgcx);
+                let is_aix = target_is_aix(cgcx);
                 match get_bitcode_slice_from_object_data(
                     child.data(&*archive_data).expect("corrupt rlib"),
+                    is_apple,
+                    is_aix,
                 ) {
                     Ok(data) => {
                         let module = SerializedModule::FromRlib(data.to_vec());
@@ -144,19 +151,19 @@ fn prepare_lto(
     Ok((symbols_below_threshold, upstream_modules))
 }
 
-fn get_bitcode_slice_from_object_data(obj: &[u8]) -> Result<&[u8], LtoBitcodeFromRlib> {
+fn get_bitcode_slice_from_object_data(
+    obj: &[u8],
+    is_apple: bool,
+    is_aix: bool,
+) -> Result<&[u8], LtoBitcodeFromRlib> {
     // The object crate doesn't understand bitcode files, but we can just sniff for the possible
     // magic strings here and return the whole slice directly.
     if obj.starts_with(b"\xDE\xC0\x17\x0B") || obj.starts_with(b"BC\xC0\xDE") {
         return Ok(obj);
     }
+    let section = bitcode_section_name(is_apple, is_aix).trim_end_matches('\0');
     match object::read::File::parse(obj) {
-        Ok(f) => match f
-            .section_by_name(".llvmbc")
-            .or_else(|| f.section_by_name(".llvm.lto"))
-            .or_else(|| f.section_by_name("__LLVM,__bitcode"))
-            .or_else(|| f.section_by_name(".ipa"))
-        {
+        Ok(f) => match f.section_by_name(section) {
             Some(d) => Ok(d.data().unwrap()),
             None => Err(LtoBitcodeFromRlib {
                 llvm_err: "Bitcode section not found in object file".to_string(),

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -853,6 +853,27 @@ fn create_section_with_flags_asm(section_name: &str, section_flags: &str, data:
     asm
 }
 
+pub(crate) fn bitcode_section_name(is_apple: bool, is_aix: bool) -> &'static str {
+    if is_apple {
+        "__LLVM,__bitcode\0"
+    } else if is_aix {
+        ".ipa\0"
+    } else {
+        ".llvmbc\0"
+    }
+}
+
+pub(crate) fn target_is_apple(cgcx: &CodegenContext<LlvmCodegenBackend>) -> bool {
+    cgcx.opts.target_triple.triple().contains("-ios")
+        || cgcx.opts.target_triple.triple().contains("-darwin")
+        || cgcx.opts.target_triple.triple().contains("-tvos")
+        || cgcx.opts.target_triple.triple().contains("-watchos")
+}
+
+pub(crate) fn target_is_aix(cgcx: &CodegenContext<LlvmCodegenBackend>) -> bool {
+    cgcx.opts.target_triple.triple().contains("-aix")
+}
+
 /// 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
@@ -913,11 +934,8 @@ unsafe fn embed_bitcode(
     // Unfortunately, LLVM provides no way to set custom section flags. For ELF
     // and COFF we emit the sections using module level inline assembly for that
     // reason (see issue #90326 for historical background).
-    let is_aix = cgcx.opts.target_triple.triple().contains("-aix");
-    let is_apple = cgcx.opts.target_triple.triple().contains("-ios")
-        || cgcx.opts.target_triple.triple().contains("-darwin")
-        || cgcx.opts.target_triple.triple().contains("-tvos")
-        || cgcx.opts.target_triple.triple().contains("-watchos");
+    let is_aix = target_is_aix(cgcx);
+    let is_apple = target_is_apple(cgcx);
     if is_apple
         || is_aix
         || cgcx.opts.target_triple.triple().starts_with("wasm")
@@ -932,13 +950,7 @@ unsafe fn embed_bitcode(
         );
         llvm::LLVMSetInitializer(llglobal, llconst);
 
-        let section = if is_apple {
-            "__LLVM,__bitcode\0"
-        } else if is_aix {
-            ".ipa\0"
-        } else {
-            ".llvmbc\0"
-        };
+        let section = bitcode_section_name(is_apple, is_aix);
         llvm::LLVMSetSection(llglobal, section.as_ptr().cast());
         llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
         llvm::LLVMSetGlobalConstant(llglobal, llvm::True);