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4560efe46c
This makes load generation compatible with opaque pointers. The generation of nontemporal copies still accesses the pointer element type, as fixing this requires more movement.
72 lines
3.0 KiB
Rust
72 lines
3.0 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_codegen_ssa::traits::*;
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use rustc_middle::bug;
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use rustc_session::config::DebugInfo;
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use rustc_span::symbol::sym;
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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(bx.type_i8(), 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::LLVMSetUnnamedAddress(section_var, llvm::UnnamedAddr::Global);
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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 = cx
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.tcx
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.sess
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.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.emit_debug_gdb_scripts
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}
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