1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // .debug_gdb_scripts binary section.
15 use common::CodegenCx;
17 use rustc::session::config::DebugInfo;
19 use rustc_codegen_ssa::interfaces::*;
24 /// Inserts a side-effect free instruction sequence that makes sure that the
25 /// .debug_gdb_scripts global is referenced, so it isn't removed by the linker.
26 pub fn insert_reference_to_gdb_debug_scripts_section_global(bx: &mut Builder) {
27 if needs_gdb_debug_scripts_section(bx.cx()) {
28 let gdb_debug_scripts_section = get_or_insert_gdb_debug_scripts_section_global(bx.cx());
29 // Load just the first byte as that's all that's necessary to force
30 // LLVM to keep around the reference to the global.
31 let indices = [bx.cx().const_i32(0), bx.cx().const_i32(0)];
32 let element = bx.inbounds_gep(gdb_debug_scripts_section, &indices);
33 let volative_load_instruction = bx.volatile_load(element);
35 llvm::LLVMSetAlignment(volative_load_instruction, 1);
40 /// Allocates the global variable responsible for the .debug_gdb_scripts binary
42 pub fn get_or_insert_gdb_debug_scripts_section_global(cx: &CodegenCx<'ll, '_>)
44 let c_section_var_name = "__rustc_debug_gdb_scripts_section__\0";
45 let section_var_name = &c_section_var_name[..c_section_var_name.len()-1];
47 let section_var = unsafe {
48 llvm::LLVMGetNamedGlobal(cx.llmod,
49 c_section_var_name.as_ptr() as *const _)
52 section_var.unwrap_or_else(|| {
53 let section_name = b".debug_gdb_scripts\0";
54 let section_contents = b"\x01gdb_load_rust_pretty_printers.py\0";
57 let llvm_type = cx.type_array(cx.type_i8(),
58 section_contents.len() as u64);
60 let section_var = cx.define_global(section_var_name,
61 llvm_type).unwrap_or_else(||{
62 bug!("symbol `{}` is already defined", section_var_name)
64 llvm::LLVMSetSection(section_var, section_name.as_ptr() as *const _);
65 llvm::LLVMSetInitializer(section_var, cx.const_bytes(section_contents));
66 llvm::LLVMSetGlobalConstant(section_var, llvm::True);
67 llvm::LLVMSetUnnamedAddr(section_var, llvm::True);
68 llvm::LLVMRustSetLinkage(section_var, llvm::Linkage::LinkOnceODRLinkage);
69 // This should make sure that the whole section is not larger than
70 // the string it contains. Otherwise we get a warning from GDB.
71 llvm::LLVMSetAlignment(section_var, 1);
77 pub fn needs_gdb_debug_scripts_section(cx: &CodegenCx) -> bool {
78 let omit_gdb_pretty_printer_section =
79 attr::contains_name(&cx.tcx.hir.krate_attrs(),
80 "omit_gdb_pretty_printer_section");
82 !omit_gdb_pretty_printer_section &&
83 cx.sess().opts.debuginfo != DebugInfo::None &&
84 cx.sess().target.target.options.emit_debug_gdb_scripts