1 //! Declare various LLVM values.
3 //! Prefer using functions and methods from this module rather than calling LLVM
4 //! functions directly. These functions do some additional work to ensure we do
5 //! the right thing given the preconceptions of codegen.
7 //! Some useful guidelines:
9 //! * Use declare_* family of methods if you are declaring, but are not
10 //! interested in defining the Value they return.
11 //! * Use define_* family of methods when you might be defining the Value.
12 //! * When in doubt, define.
14 use crate::abi::{FnAbi, FnAbiLlvmExt};
15 use crate::attributes;
16 use crate::context::CodegenCx;
18 use crate::llvm::AttributePlace::Function;
19 use crate::type_::Type;
20 use crate::value::Value;
23 use rustc_codegen_ssa::traits::*;
24 use rustc_data_structures::small_c_str::SmallCStr;
26 /// Declare a function.
28 /// If there’s a value with the same name already declared, the function will
29 /// update the declaration and return existing Value instead.
31 cx: &CodegenCx<'ll, '_>,
33 callconv: llvm::CallConv,
36 debug!("declare_raw_fn(name={:?}, ty={:?})", name, ty);
37 let namebuf = SmallCStr::new(name);
38 let llfn = unsafe { llvm::LLVMRustGetOrInsertFunction(cx.llmod, namebuf.as_ptr(), ty) };
40 llvm::SetFunctionCallConv(llfn, callconv);
41 // Function addresses in Rust are never significant, allowing functions to
43 llvm::SetUnnamedAddr(llfn, true);
45 if cx.tcx.sess.opts.cg.no_redzone.unwrap_or(cx.tcx.sess.target.target.options.disable_redzone) {
46 llvm::Attribute::NoRedZone.apply_llfn(Function, llfn);
49 attributes::default_optimisation_attrs(cx.tcx.sess, llfn);
50 attributes::non_lazy_bind(cx.sess(), llfn);
54 impl DeclareMethods<'tcx> for CodegenCx<'ll, 'tcx> {
55 fn declare_global(&self, name: &str, ty: &'ll Type) -> &'ll Value {
56 debug!("declare_global(name={:?})", name);
57 unsafe { llvm::LLVMRustGetOrInsertGlobal(self.llmod, name.as_ptr().cast(), name.len(), ty) }
60 fn declare_cfn(&self, name: &str, fn_type: &'ll Type) -> &'ll Value {
61 declare_raw_fn(self, name, llvm::CCallConv, fn_type)
64 fn declare_fn(&self, name: &str, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> &'ll Value {
65 debug!("declare_rust_fn(name={:?}, fn_abi={:?})", name, fn_abi);
67 let llfn = declare_raw_fn(self, name, fn_abi.llvm_cconv(), fn_abi.llvm_type(self));
68 fn_abi.apply_attrs_llfn(self, llfn);
72 fn define_global(&self, name: &str, ty: &'ll Type) -> Option<&'ll Value> {
73 if self.get_defined_value(name).is_some() {
76 Some(self.declare_global(name, ty))
80 fn define_private_global(&self, ty: &'ll Type) -> &'ll Value {
81 unsafe { llvm::LLVMRustInsertPrivateGlobal(self.llmod, ty) }
84 fn get_declared_value(&self, name: &str) -> Option<&'ll Value> {
85 debug!("get_declared_value(name={:?})", name);
86 let namebuf = SmallCStr::new(name);
87 unsafe { llvm::LLVMRustGetNamedValue(self.llmod, namebuf.as_ptr()) }
90 fn get_defined_value(&self, name: &str) -> Option<&'ll Value> {
91 self.get_declared_value(name).and_then(|val| {
92 let declaration = unsafe { llvm::LLVMIsDeclaration(val) != 0 };
93 if !declaration { Some(val) } else { None }