1 // .debug_gdb_scripts binary section.
5 use crate::builder::Builder;
6 use crate::common::CodegenCx;
7 use crate::value::Value;
9 use rustc::session::config::DebugInfo;
10 use rustc_codegen_ssa::traits::*;
12 use rustc_span::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, '_>) -> &'ll Value {
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];
38 unsafe { llvm::LLVMGetNamedGlobal(cx.llmod, c_section_var_name.as_ptr().cast()) };
40 section_var.unwrap_or_else(|| {
41 let section_name = b".debug_gdb_scripts\0";
42 let section_contents = b"\x01gdb_load_rust_pretty_printers.py\0";
45 let llvm_type = cx.type_array(cx.type_i8(), section_contents.len() as u64);
48 .define_global(section_var_name, llvm_type)
49 .unwrap_or_else(|| bug!("symbol `{}` is already defined", section_var_name));
50 llvm::LLVMSetSection(section_var, section_name.as_ptr().cast());
51 llvm::LLVMSetInitializer(section_var, cx.const_bytes(section_contents));
52 llvm::LLVMSetGlobalConstant(section_var, llvm::True);
53 llvm::LLVMSetUnnamedAddr(section_var, llvm::True);
54 llvm::LLVMRustSetLinkage(section_var, llvm::Linkage::LinkOnceODRLinkage);
55 // This should make sure that the whole section is not larger than
56 // the string it contains. Otherwise we get a warning from GDB.
57 llvm::LLVMSetAlignment(section_var, 1);
63 pub fn needs_gdb_debug_scripts_section(cx: &CodegenCx<'_, '_>) -> bool {
64 let omit_gdb_pretty_printer_section =
65 attr::contains_name(&cx.tcx.hir().krate_attrs(), sym::omit_gdb_pretty_printer_section);
67 !omit_gdb_pretty_printer_section
68 && cx.sess().opts.debuginfo != DebugInfo::None
69 && cx.sess().target.target.options.emit_debug_gdb_scripts