1 // .debug_gdb_scripts binary section.
5 use crate::common::CodegenCx;
6 use crate::builder::Builder;
7 use crate::value::Value;
8 use rustc::session::config::DebugInfo;
9 use rustc_codegen_ssa::traits::*;
14 /// Inserts a side-effect free instruction sequence that makes sure that the
15 /// .debug_gdb_scripts global is referenced, so it isn't removed by the linker.
16 pub fn insert_reference_to_gdb_debug_scripts_section_global(bx: &mut Builder<'_, '_, '_>) {
17 if needs_gdb_debug_scripts_section(bx) {
18 let gdb_debug_scripts_section = get_or_insert_gdb_debug_scripts_section_global(bx);
19 // Load just the first byte as that's all that's necessary to force
20 // LLVM to keep around the reference to the global.
21 let indices = [bx.const_i32(0), bx.const_i32(0)];
22 let element = bx.inbounds_gep(gdb_debug_scripts_section, &indices);
23 let volative_load_instruction = bx.volatile_load(element);
25 llvm::LLVMSetAlignment(volative_load_instruction, 1);
30 /// Allocates the global variable responsible for the .debug_gdb_scripts binary
32 pub fn get_or_insert_gdb_debug_scripts_section_global(cx: &CodegenCx<'ll, '_>)
34 let c_section_var_name = "__rustc_debug_gdb_scripts_section__\0";
35 let section_var_name = &c_section_var_name[..c_section_var_name.len()-1];
37 let section_var = unsafe {
38 llvm::LLVMGetNamedGlobal(cx.llmod,
39 c_section_var_name.as_ptr() as *const _)
42 section_var.unwrap_or_else(|| {
43 let section_name = b".debug_gdb_scripts\0";
44 let section_contents = b"\x01gdb_load_rust_pretty_printers.py\0";
47 let llvm_type = cx.type_array(cx.type_i8(),
48 section_contents.len() as u64);
50 let section_var = cx.define_global(section_var_name,
51 llvm_type).unwrap_or_else(||{
52 bug!("symbol `{}` is already defined", section_var_name)
54 llvm::LLVMSetSection(section_var, section_name.as_ptr() as *const _);
55 llvm::LLVMSetInitializer(section_var, cx.const_bytes(section_contents));
56 llvm::LLVMSetGlobalConstant(section_var, llvm::True);
57 llvm::LLVMSetUnnamedAddr(section_var, llvm::True);
58 llvm::LLVMRustSetLinkage(section_var, llvm::Linkage::LinkOnceODRLinkage);
59 // This should make sure that the whole section is not larger than
60 // the string it contains. Otherwise we get a warning from GDB.
61 llvm::LLVMSetAlignment(section_var, 1);
67 pub fn needs_gdb_debug_scripts_section(cx: &CodegenCx<'_, '_>) -> bool {
68 let omit_gdb_pretty_printer_section =
69 attr::contains_name(&cx.tcx.hir().krate_attrs(),
70 "omit_gdb_pretty_printer_section");
72 !omit_gdb_pretty_printer_section &&
73 cx.sess().opts.debuginfo != DebugInfo::None &&
74 cx.sess().target.target.options.emit_debug_gdb_scripts