71 lines
2.9 KiB
Rust
71 lines
2.9 KiB
Rust
// .debug_gdb_scripts binary section.
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use crate::llvm;
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use crate::builder::Builder;
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use crate::common::CodegenCx;
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use crate::value::Value;
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use rustc::bug;
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use rustc::session::config::DebugInfo;
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use rustc_codegen_ssa::traits::*;
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use rustc_span::symbol::sym;
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use syntax::attr;
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/// Inserts a side-effect free instruction sequence that makes sure that the
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/// .debug_gdb_scripts global is referenced, so it isn't removed by the linker.
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pub fn insert_reference_to_gdb_debug_scripts_section_global(bx: &mut Builder<'_, '_, '_>) {
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if needs_gdb_debug_scripts_section(bx) {
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let gdb_debug_scripts_section = get_or_insert_gdb_debug_scripts_section_global(bx);
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// Load just the first byte as that's all that's necessary to force
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// LLVM to keep around the reference to the global.
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let indices = [bx.const_i32(0), bx.const_i32(0)];
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let element = bx.inbounds_gep(gdb_debug_scripts_section, &indices);
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let volative_load_instruction = bx.volatile_load(element);
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unsafe {
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llvm::LLVMSetAlignment(volative_load_instruction, 1);
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}
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}
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}
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/// Allocates the global variable responsible for the .debug_gdb_scripts binary
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/// section.
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pub fn get_or_insert_gdb_debug_scripts_section_global(cx: &CodegenCx<'ll, '_>) -> &'ll Value {
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let c_section_var_name = "__rustc_debug_gdb_scripts_section__\0";
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let section_var_name = &c_section_var_name[..c_section_var_name.len() - 1];
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let section_var =
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unsafe { llvm::LLVMGetNamedGlobal(cx.llmod, c_section_var_name.as_ptr().cast()) };
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section_var.unwrap_or_else(|| {
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let section_name = b".debug_gdb_scripts\0";
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let section_contents = b"\x01gdb_load_rust_pretty_printers.py\0";
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unsafe {
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let llvm_type = cx.type_array(cx.type_i8(), section_contents.len() as u64);
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let section_var = cx
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.define_global(section_var_name, llvm_type)
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.unwrap_or_else(|| bug!("symbol `{}` is already defined", section_var_name));
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llvm::LLVMSetSection(section_var, section_name.as_ptr().cast());
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llvm::LLVMSetInitializer(section_var, cx.const_bytes(section_contents));
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llvm::LLVMSetGlobalConstant(section_var, llvm::True);
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llvm::LLVMSetUnnamedAddr(section_var, llvm::True);
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llvm::LLVMRustSetLinkage(section_var, llvm::Linkage::LinkOnceODRLinkage);
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// This should make sure that the whole section is not larger than
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// the string it contains. Otherwise we get a warning from GDB.
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llvm::LLVMSetAlignment(section_var, 1);
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section_var
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}
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})
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}
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pub fn needs_gdb_debug_scripts_section(cx: &CodegenCx<'_, '_>) -> bool {
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let omit_gdb_pretty_printer_section =
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attr::contains_name(&cx.tcx.hir().krate_attrs(), sym::omit_gdb_pretty_printer_section);
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!omit_gdb_pretty_printer_section
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&& cx.sess().opts.debuginfo != DebugInfo::None
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&& cx.sess().target.target.options.emit_debug_gdb_scripts
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}
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