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::*;
12 use syntax::symbol::sym;
15 /// Inserts a side-effect free instruction sequence that makes sure that the
16 /// .debug_gdb_scripts global is referenced, so it isn't removed by the linker.
17 pub fn insert_reference_to_gdb_debug_scripts_section_global(bx: &mut Builder<'_, '_, '_>) {
18 if needs_gdb_debug_scripts_section(bx) {
19 let gdb_debug_scripts_section = get_or_insert_gdb_debug_scripts_section_global(bx);
20 // Load just the first byte as that's all that's necessary to force
21 // LLVM to keep around the reference to the global.
22 let indices = [bx.const_i32(0), bx.const_i32(0)];
23 let element = bx.inbounds_gep(gdb_debug_scripts_section, &indices);
24 let volative_load_instruction = bx.volatile_load(element);
26 llvm::LLVMSetAlignment(volative_load_instruction, 1);
31 /// Allocates the global variable responsible for the .debug_gdb_scripts binary
33 pub fn get_or_insert_gdb_debug_scripts_section_global(cx: &CodegenCx<'ll, '_>)
35 let c_section_var_name = "__rustc_debug_gdb_scripts_section__\0";
36 let section_var_name = &c_section_var_name[..c_section_var_name.len()-1];
38 let section_var = unsafe {
39 llvm::LLVMGetNamedGlobal(cx.llmod,
40 c_section_var_name.as_ptr() as *const _)
43 section_var.unwrap_or_else(|| {
44 let section_name = b".debug_gdb_scripts\0";
45 let section_contents = b"\x01gdb_load_rust_pretty_printers.py\0";
48 let llvm_type = cx.type_array(cx.type_i8(),
49 section_contents.len() as u64);
51 let section_var = cx.define_global(section_var_name,
52 llvm_type).unwrap_or_else(||{
53 bug!("symbol `{}` is already defined", section_var_name)
55 llvm::LLVMSetSection(section_var, section_name.as_ptr() as *const _);
56 llvm::LLVMSetInitializer(section_var, cx.const_bytes(section_contents));
57 llvm::LLVMSetGlobalConstant(section_var, llvm::True);
58 llvm::LLVMSetUnnamedAddr(section_var, llvm::True);
59 llvm::LLVMRustSetLinkage(section_var, llvm::Linkage::LinkOnceODRLinkage);
60 // This should make sure that the whole section is not larger than
61 // the string it contains. Otherwise we get a warning from GDB.
62 llvm::LLVMSetAlignment(section_var, 1);
68 pub fn needs_gdb_debug_scripts_section(cx: &CodegenCx<'_, '_>) -> bool {
69 let omit_gdb_pretty_printer_section =
70 attr::contains_name(&cx.tcx.hir().krate_attrs(), sym::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