compiler/rustc_codegen_cranelift/src/global_asm.rs

   1 //! The AOT driver uses [`cranelift_object`] to write object files suitable for linking into a
   2 //! standalone executable.
   3
   4 use std::io::Write;
   5 use std::path::PathBuf;
   6 use std::process::{Command, Stdio};
   7 use std::sync::Arc;
   8
   9 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
  10 use rustc_hir::ItemId;
  11 use rustc_session::config::{OutputFilenames, OutputType};
  12
  13 use crate::prelude::*;
  14
  15 pub(crate) fn codegen_global_asm_item(tcx: TyCtxt<'_>, global_asm: &mut String, item_id: ItemId) {
  16     let item = tcx.hir().item(item_id);
  17     if let rustc_hir::ItemKind::GlobalAsm(asm) = item.kind {
  18         if !asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
  19             global_asm.push_str("\n.intel_syntax noprefix\n");
  20         } else {
  21             global_asm.push_str("\n.att_syntax\n");
  22         }
  23         for piece in asm.template {
  24             match *piece {
  25                 InlineAsmTemplatePiece::String(ref s) => global_asm.push_str(s),
  26                 InlineAsmTemplatePiece::Placeholder { .. } => todo!(),
  27             }
  28         }
  29         global_asm.push_str("\n.att_syntax\n\n");
  30     } else {
  31         bug!("Expected GlobalAsm found {:?}", item);
  32     }
  33 }
  34
  35 #[derive(Debug)]
  36 pub(crate) struct GlobalAsmConfig {
  37     asm_enabled: bool,
  38     assembler: PathBuf,
  39     pub(crate) output_filenames: Arc<OutputFilenames>,
  40 }
  41
  42 impl GlobalAsmConfig {
  43     pub(crate) fn new(tcx: TyCtxt<'_>) -> Self {
  44         let asm_enabled = cfg!(feature = "inline_asm") && !tcx.sess.target.is_like_windows;
  45
  46         GlobalAsmConfig {
  47             asm_enabled,
  48             assembler: crate::toolchain::get_toolchain_binary(tcx.sess, "as"),
  49             output_filenames: tcx.output_filenames(()).clone(),
  50         }
  51     }
  52 }
  53
  54 pub(crate) fn compile_global_asm(
  55     config: &GlobalAsmConfig,
  56     cgu_name: &str,
  57     global_asm: &str,
  58 ) -> Result<Option<PathBuf>, String> {
  59     if global_asm.is_empty() {
  60         return Ok(None);
  61     }
  62
  63     if !config.asm_enabled {
  64         if global_asm.contains("__rust_probestack") {
  65             return Ok(None);
  66         }
  67
  68         // FIXME fix linker error on macOS
  69         if cfg!(not(feature = "inline_asm")) {
  70             return Err(
  71                 "asm! and global_asm! support is disabled while compiling rustc_codegen_cranelift"
  72                     .to_owned(),
  73             );
  74         } else {
  75             return Err("asm! and global_asm! are not yet supported on Windows".to_owned());
  76         }
  77     }
  78
  79     // Remove all LLVM style comments
  80     let global_asm = global_asm
  81         .lines()
  82         .map(|line| if let Some(index) = line.find("//") { &line[0..index] } else { line })
  83         .collect::<Vec<_>>()
  84         .join("\n");
  85
  86     let output_object_file = config.output_filenames.temp_path(OutputType::Object, Some(cgu_name));
  87
  88     // Assemble `global_asm`
  89     let global_asm_object_file = add_file_stem_postfix(output_object_file.clone(), ".asm");
  90     let mut child = Command::new(&config.assembler)
  91         .arg("-o")
  92         .arg(&global_asm_object_file)
  93         .stdin(Stdio::piped())
  94         .spawn()
  95         .expect("Failed to spawn `as`.");
  96     child.stdin.take().unwrap().write_all(global_asm.as_bytes()).unwrap();
  97     let status = child.wait().expect("Failed to wait for `as`.");
  98     if !status.success() {
  99         return Err(format!("Failed to assemble `{}`", global_asm));
 100     }
 101
 102     Ok(Some(global_asm_object_file))
 103 }
 104
 105 pub(crate) fn add_file_stem_postfix(mut path: PathBuf, postfix: &str) -> PathBuf {
 106     let mut new_filename = path.file_stem().unwrap().to_owned();
 107     new_filename.push(postfix);
 108     if let Some(extension) = path.extension() {
 109         new_filename.push(".");
 110         new_filename.push(extension);
 111     }
 112     path.set_file_name(new_filename);
 113     path
 114 }