Rollup merge of #109515 - bzEq:aix-linker, r=petrochenkov

Add AixLinker to support linking on AIX

AIX linker has a different cli style from other existing linkers.
It is documented in https://www.ibm.com/docs/en/aix/7.1?topic=l-ld-command.

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -133,6 +133,9 @@ pub fn get_linker<'a>(
         LinkerFlavor::Unix(Cc::No) if sess.target.os == "l4re" => {
             Box::new(L4Bender::new(cmd, sess)) as Box<dyn Linker>
         }
+        LinkerFlavor::Unix(Cc::No) if sess.target.os == "aix" => {
+            Box::new(AixLinker::new(cmd, sess)) as Box<dyn Linker>
+        }
         LinkerFlavor::WasmLld(Cc::No) => Box::new(WasmLd::new(cmd, sess)) as Box<dyn Linker>,
         LinkerFlavor::Gnu(cc, _)
         | LinkerFlavor::Darwin(cc, _)
@@ -1474,6 +1477,177 @@ impl<'a> L4Bender<'a> {
     }
 }
 
+/// Linker for AIX.
+pub struct AixLinker<'a> {
+    cmd: Command,
+    sess: &'a Session,
+    hinted_static: bool,
+}
+
+impl<'a> AixLinker<'a> {
+    pub fn new(cmd: Command, sess: &'a Session) -> AixLinker<'a> {
+        AixLinker { cmd: cmd, sess: sess, hinted_static: false }
+    }
+
+    fn hint_static(&mut self) {
+        if !self.hinted_static {
+            self.cmd.arg("-bstatic");
+            self.hinted_static = true;
+        }
+    }
+
+    fn hint_dynamic(&mut self) {
+        if self.hinted_static {
+            self.cmd.arg("-bdynamic");
+            self.hinted_static = false;
+        }
+    }
+
+    fn build_dylib(&mut self, _out_filename: &Path) {
+        self.cmd.arg("-bM:SRE");
+        self.cmd.arg("-bnoentry");
+        // FIXME: Use CreateExportList utility to create export list
+        // and remove -bexpfull.
+        self.cmd.arg("-bexpfull");
+    }
+}
+
+impl<'a> Linker for AixLinker<'a> {
+    fn link_dylib(&mut self, lib: &str, _verbatim: bool, _as_needed: bool) {
+        self.hint_dynamic();
+        self.cmd.arg(format!("-l{}", lib));
+    }
+
+    fn link_staticlib(&mut self, lib: &str, _verbatim: bool) {
+        self.hint_static();
+        self.cmd.arg(format!("-l{}", lib));
+    }
+
+    fn link_rlib(&mut self, lib: &Path) {
+        self.hint_static();
+        self.cmd.arg(lib);
+    }
+
+    fn include_path(&mut self, path: &Path) {
+        self.cmd.arg("-L").arg(path);
+    }
+
+    fn framework_path(&mut self, _: &Path) {
+        bug!("frameworks are not supported on AIX");
+    }
+
+    fn output_filename(&mut self, path: &Path) {
+        self.cmd.arg("-o").arg(path);
+    }
+
+    fn add_object(&mut self, path: &Path) {
+        self.cmd.arg(path);
+    }
+
+    fn full_relro(&mut self) {}
+
+    fn partial_relro(&mut self) {}
+
+    fn no_relro(&mut self) {}
+
+    fn cmd(&mut self) -> &mut Command {
+        &mut self.cmd
+    }
+
+    fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path) {
+        match output_kind {
+            LinkOutputKind::DynamicDylib => {
+                self.hint_dynamic();
+                self.build_dylib(out_filename);
+            }
+            LinkOutputKind::StaticDylib => {
+                self.hint_static();
+                self.build_dylib(out_filename);
+            }
+            _ => {}
+        }
+    }
+
+    fn link_rust_dylib(&mut self, lib: &str, _: &Path) {
+        self.hint_dynamic();
+        self.cmd.arg(format!("-l{}", lib));
+    }
+
+    fn link_framework(&mut self, _framework: &str, _as_needed: bool) {
+        bug!("frameworks not supported on AIX");
+    }
+
+    fn link_whole_staticlib(&mut self, lib: &str, verbatim: bool, search_path: &[PathBuf]) {
+        self.hint_static();
+        let lib = find_native_static_library(lib, verbatim, search_path, &self.sess);
+        self.cmd.arg(format!("-bkeepfile:{}", lib.to_str().unwrap()));
+    }
+
+    fn link_whole_rlib(&mut self, lib: &Path) {
+        self.hint_static();
+        self.cmd.arg(format!("-bkeepfile:{}", lib.to_str().unwrap()));
+    }
+
+    fn gc_sections(&mut self, _keep_metadata: bool) {
+        self.cmd.arg("-bgc");
+    }
+
+    fn no_gc_sections(&mut self) {
+        self.cmd.arg("-bnogc");
+    }
+
+    fn optimize(&mut self) {}
+
+    fn pgo_gen(&mut self) {}
+
+    fn control_flow_guard(&mut self) {}
+
+    fn debuginfo(&mut self, strip: Strip, _: &[PathBuf]) {
+        match strip {
+            Strip::None => {}
+            // FIXME: -s strips the symbol table, line number information
+            // and relocation information.
+            Strip::Debuginfo | Strip::Symbols => {
+                self.cmd.arg("-s");
+            }
+        }
+    }
+
+    fn no_crt_objects(&mut self) {}
+
+    fn no_default_libraries(&mut self) {}
+
+    fn export_symbols(&mut self, tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
+        let path = tmpdir.join("list.exp");
+        let res: io::Result<()> = try {
+            let mut f = BufWriter::new(File::create(&path)?);
+            // TODO: use llvm-nm to generate export list.
+            for symbol in symbols {
+                debug!("  _{}", symbol);
+                writeln!(f, "  {}", symbol)?;
+            }
+        };
+        if let Err(e) = res {
+            self.sess.fatal(&format!("failed to write export file: {}", e));
+        }
+        self.cmd.arg(format!("-bE:{}", path.to_str().unwrap()));
+    }
+
+    fn subsystem(&mut self, _subsystem: &str) {}
+
+    fn reset_per_library_state(&mut self) {
+        self.hint_dynamic();
+    }
+
+    fn linker_plugin_lto(&mut self) {}
+
+    fn add_eh_frame_header(&mut self) {}
+
+    fn add_no_exec(&mut self) {}
+
+    fn add_as_needed(&mut self) {}
+}
+
 fn for_each_exported_symbols_include_dep<'tcx>(
     tcx: TyCtxt<'tcx>,
     crate_type: CrateType,