1 files changed, 114 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/global_asm.rs b/compiler/rustc_codegen_cranelift/src/global_asm.rs
new file mode 100644
index 000000000..dcbcaba30
--- /dev/null
+++ b/compiler/rustc_codegen_cranelift/src/global_asm.rs
@@ -0,0 +1,114 @@
+//! The AOT driver uses [`cranelift_object`] to write object files suitable for linking into a
+//! standalone executable.
+
+use std::io::Write;
+use std::path::PathBuf;
+use std::process::{Command, Stdio};
+use std::sync::Arc;
+
+use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
+use rustc_hir::ItemId;
+use rustc_session::config::{OutputFilenames, OutputType};
+
+use crate::prelude::*;
+
+pub(crate) fn codegen_global_asm_item(tcx: TyCtxt<'_>, global_asm: &mut String, item_id: ItemId) {
+    let item = tcx.hir().item(item_id);
+    if let rustc_hir::ItemKind::GlobalAsm(asm) = item.kind {
+        if !asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
+            global_asm.push_str("\n.intel_syntax noprefix\n");
+        } else {
+            global_asm.push_str("\n.att_syntax\n");
+        }
+        for piece in asm.template {
+            match *piece {
+                InlineAsmTemplatePiece::String(ref s) => global_asm.push_str(s),
+                InlineAsmTemplatePiece::Placeholder { .. } => todo!(),
+            }
+        }
+        global_asm.push_str("\n.att_syntax\n\n");
+    } else {
+        bug!("Expected GlobalAsm found {:?}", item);
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct GlobalAsmConfig {
+    asm_enabled: bool,
+    assembler: PathBuf,
+    pub(crate) output_filenames: Arc<OutputFilenames>,
+}
+
+impl GlobalAsmConfig {
+    pub(crate) fn new(tcx: TyCtxt<'_>) -> Self {
+        let asm_enabled = cfg!(feature = "inline_asm") && !tcx.sess.target.is_like_windows;
+
+        GlobalAsmConfig {
+            asm_enabled,
+            assembler: crate::toolchain::get_toolchain_binary(tcx.sess, "as"),
+            output_filenames: tcx.output_filenames(()).clone(),
+        }
+    }
+}
+
+pub(crate) fn compile_global_asm(
+    config: &GlobalAsmConfig,
+    cgu_name: &str,
+    global_asm: &str,
+) -> Result<Option<PathBuf>, String> {
+    if global_asm.is_empty() {
+        return Ok(None);
+    }
+
+    if !config.asm_enabled {
+        if global_asm.contains("__rust_probestack") {
+            return Ok(None);
+        }
+
+        // FIXME fix linker error on macOS
+        if cfg!(not(feature = "inline_asm")) {
+            return Err(
+                "asm! and global_asm! support is disabled while compiling rustc_codegen_cranelift"
+                    .to_owned(),
+            );
+        } else {
+            return Err("asm! and global_asm! are not yet supported on Windows".to_owned());
+        }
+    }
+
+    // Remove all LLVM style comments
+    let global_asm = global_asm
+        .lines()
+        .map(|line| if let Some(index) = line.find("//") { &line[0..index] } else { line })
+        .collect::<Vec<_>>()
+        .join("\n");
+
+    let output_object_file = config.output_filenames.temp_path(OutputType::Object, Some(cgu_name));
+
+    // Assemble `global_asm`
+    let global_asm_object_file = add_file_stem_postfix(output_object_file.clone(), ".asm");
+    let mut child = Command::new(&config.assembler)
+        .arg("-o")
+        .arg(&global_asm_object_file)
+        .stdin(Stdio::piped())
+        .spawn()
+        .expect("Failed to spawn `as`.");
+    child.stdin.take().unwrap().write_all(global_asm.as_bytes()).unwrap();
+    let status = child.wait().expect("Failed to wait for `as`.");
+    if !status.success() {
+        return Err(format!("Failed to assemble `{}`", global_asm));
+    }
+
+    Ok(Some(global_asm_object_file))
+}
+
+pub(crate) fn add_file_stem_postfix(mut path: PathBuf, postfix: &str) -> PathBuf {
+    let mut new_filename = path.file_stem().unwrap().to_owned();
+    new_filename.push(postfix);
+    if let Some(extension) = path.extension() {
+        new_filename.push(".");
+        new_filename.push(extension);
+    }
+    path.set_file_name(new_filename);
+    path
+}