1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
10 //! Declare various LLVM values.
12 //! Prefer using functions and methods from this module rather than calling LLVM
13 //! functions directly. These functions do some additional work to ensure we do
14 //! the right thing given the preconceptions of trans.
16 //! Some useful guidelines:
18 //! * Use declare_* family of methods if you are declaring, but are not
19 //! interested in defining the ValueRef they return.
20 //! * Use define_* family of methods when you might be defining the ValueRef.
21 //! * When in doubt, define.
23 use llvm::{self, ValueRef};
24 use llvm::AttributePlace::Function;
26 use abi::{Abi, FnType};
28 use context::CrateContext;
34 use std::ffi::CString;
37 /// Declare a global value.
39 /// If there’s a value with the same name already declared, the function will
40 /// return its ValueRef instead.
41 pub fn declare_global(ccx: &CrateContext, name: &str, ty: Type) -> llvm::ValueRef {
42 debug!("declare_global(name={:?})", name);
43 let namebuf = CString::new(name).unwrap_or_else(|_|{
44 bug!("name {:?} contains an interior null byte", name)
47 llvm::LLVMRustGetOrInsertGlobal(ccx.llmod(), namebuf.as_ptr(), ty.to_ref())
52 /// Declare a function.
54 /// If there’s a value with the same name already declared, the function will
55 /// update the declaration and return existing ValueRef instead.
56 fn declare_raw_fn(ccx: &CrateContext, name: &str, callconv: llvm::CallConv, ty: Type) -> ValueRef {
57 debug!("declare_raw_fn(name={:?}, ty={:?})", name, ty);
58 let namebuf = CString::new(name).unwrap_or_else(|_|{
59 bug!("name {:?} contains an interior null byte", name)
62 llvm::LLVMRustGetOrInsertFunction(ccx.llmod(), namebuf.as_ptr(), ty.to_ref())
65 llvm::SetFunctionCallConv(llfn, callconv);
66 // Function addresses in Rust are never significant, allowing functions to
68 llvm::SetUnnamedAddr(llfn, true);
70 if ccx.tcx().sess.opts.cg.no_redzone
71 .unwrap_or(ccx.tcx().sess.target.target.options.disable_redzone) {
72 llvm::Attribute::NoRedZone.apply_llfn(Function, llfn);
75 // If we're compiling the compiler-builtins crate, e.g. the equivalent of
76 // compiler-rt, then we want to implicitly compile everything with hidden
77 // visibility as we're going to link this object all over the place but
78 // don't want the symbols to get exported.
79 if attr::contains_name(ccx.tcx().hir.krate_attrs(), "compiler_builtins") {
81 llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
85 match ccx.tcx().sess.opts.cg.opt_level.as_ref().map(String::as_ref) {
87 llvm::Attribute::OptimizeForSize.apply_llfn(Function, llfn);
90 llvm::Attribute::MinSize.apply_llfn(Function, llfn);
91 llvm::Attribute::OptimizeForSize.apply_llfn(Function, llfn);
100 /// Declare a C ABI function.
102 /// Only use this for foreign function ABIs and glue. For Rust functions use
103 /// `declare_fn` instead.
105 /// If there’s a value with the same name already declared, the function will
106 /// update the declaration and return existing ValueRef instead.
107 pub fn declare_cfn(ccx: &CrateContext, name: &str, fn_type: Type) -> ValueRef {
108 declare_raw_fn(ccx, name, llvm::CCallConv, fn_type)
112 /// Declare a Rust function.
114 /// If there’s a value with the same name already declared, the function will
115 /// update the declaration and return existing ValueRef instead.
116 pub fn declare_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, name: &str,
117 fn_type: ty::Ty<'tcx>) -> ValueRef {
118 debug!("declare_rust_fn(name={:?}, fn_type={:?})", name, fn_type);
119 let ty::BareFnTy { abi, ref sig, .. } = *common::ty_fn_ty(ccx, fn_type);
120 let sig = ccx.tcx().erase_late_bound_regions_and_normalize(sig);
121 debug!("declare_rust_fn (after region erasure) sig={:?}", sig);
123 let fty = FnType::new(ccx, abi, &sig, &[]);
124 let llfn = declare_raw_fn(ccx, name, fty.cconv, fty.llvm_type(ccx));
126 // FIXME(canndrew): This is_never should really be an is_uninhabited
127 if sig.output().is_never() {
128 llvm::Attribute::NoReturn.apply_llfn(Function, llfn);
131 if abi != Abi::Rust && abi != Abi::RustCall {
132 attributes::unwind(llfn, false);
135 fty.apply_attrs_llfn(llfn);
141 /// Declare a global with an intention to define it.
143 /// Use this function when you intend to define a global. This function will
144 /// return None if the name already has a definition associated with it. In that
145 /// case an error should be reported to the user, because it usually happens due
146 /// to user’s fault (e.g. misuse of #[no_mangle] or #[export_name] attributes).
147 pub fn define_global(ccx: &CrateContext, name: &str, ty: Type) -> Option<ValueRef> {
148 if get_defined_value(ccx, name).is_some() {
151 Some(declare_global(ccx, name, ty))
155 /// Declare a Rust function with an intention to define it.
157 /// Use this function when you intend to define a function. This function will
158 /// return panic if the name already has a definition associated with it. This
159 /// can happen with #[no_mangle] or #[export_name], for example.
160 pub fn define_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
162 fn_type: ty::Ty<'tcx>) -> ValueRef {
163 if get_defined_value(ccx, name).is_some() {
164 ccx.sess().fatal(&format!("symbol `{}` already defined", name))
166 declare_fn(ccx, name, fn_type)
170 /// Declare a Rust function with an intention to define it.
172 /// Use this function when you intend to define a function. This function will
173 /// return panic if the name already has a definition associated with it. This
174 /// can happen with #[no_mangle] or #[export_name], for example.
175 pub fn define_internal_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
177 fn_type: ty::Ty<'tcx>) -> ValueRef {
178 let llfn = define_fn(ccx, name, fn_type);
179 unsafe { llvm::LLVMRustSetLinkage(llfn, llvm::Linkage::InternalLinkage) };
184 /// Get declared value by name.
185 pub fn get_declared_value(ccx: &CrateContext, name: &str) -> Option<ValueRef> {
186 debug!("get_declared_value(name={:?})", name);
187 let namebuf = CString::new(name).unwrap_or_else(|_|{
188 bug!("name {:?} contains an interior null byte", name)
190 let val = unsafe { llvm::LLVMRustGetNamedValue(ccx.llmod(), namebuf.as_ptr()) };
192 debug!("get_declared_value: {:?} value is null", name);
195 debug!("get_declared_value: {:?} => {:?}", name, Value(val));
200 /// Get defined or externally defined (AvailableExternally linkage) value by
202 pub fn get_defined_value(ccx: &CrateContext, name: &str) -> Option<ValueRef> {
203 get_declared_value(ccx, name).and_then(|val|{
204 let declaration = unsafe {
205 llvm::LLVMIsDeclaration(val) != 0