1 //! Code that is useful in various codegen modules.
3 use crate::consts::{self, const_alloc_to_llvm};
4 pub use crate::context::CodegenCx;
5 use crate::llvm::{self, BasicBlock, Bool, ConstantInt, False, OperandBundleDef, True};
6 use crate::type_::Type;
7 use crate::type_of::LayoutLlvmExt;
8 use crate::value::Value;
10 use rustc_ast::Mutability;
11 use rustc_codegen_ssa::mir::place::PlaceRef;
12 use rustc_codegen_ssa::traits::*;
13 use rustc_middle::bug;
14 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
15 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
16 use rustc_middle::ty::ScalarInt;
17 use rustc_span::symbol::Symbol;
18 use rustc_target::abi::{self, AddressSpace, HasDataLayout, Pointer, Size};
20 use libc::{c_char, c_uint};
24 * A note on nomenclature of linking: "extern", "foreign", and "upcall".
26 * An "extern" is an LLVM symbol we wind up emitting an undefined external
27 * reference to. This means "we don't have the thing in this compilation unit,
28 * please make sure you link it in at runtime". This could be a reference to
29 * C code found in a C library, or rust code found in a rust crate.
31 * Most "externs" are implicitly declared (automatically) as a result of a
32 * user declaring an extern _module_ dependency; this causes the rust driver
33 * to locate an extern crate, scan its compilation metadata, and emit extern
34 * declarations for any symbols used by the declaring crate.
36 * A "foreign" is an extern that references C (or other non-rust ABI) code.
37 * There is no metadata to scan for extern references so in these cases either
38 * a header-digester like bindgen, or manual function prototypes, have to
39 * serve as declarators. So these are usually given explicitly as prototype
40 * declarations, in rust code, with ABI attributes on them noting which ABI to
43 * An "upcall" is a foreign call generated by the compiler (not corresponding
44 * to any user-written call in the code) into the runtime library, to perform
45 * some helper task such as bringing a task to life, allocating memory, etc.
49 /// A structure representing an active landing pad for the duration of a basic
52 /// Each `Block` may contain an instance of this, indicating whether the block
53 /// is part of a landing pad or not. This is used to make decision about whether
54 /// to emit `invoke` instructions (e.g., in a landing pad we don't continue to
55 /// use `invoke`) and also about various function call metadata.
57 /// For GNU exceptions (`landingpad` + `resume` instructions) this structure is
58 /// just a bunch of `None` instances (not too interesting), but for MSVC
59 /// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data.
60 /// When inside of a landing pad, each function call in LLVM IR needs to be
61 /// annotated with which landing pad it's a part of. This is accomplished via
62 /// the `OperandBundleDef` value created for MSVC landing pads.
63 pub struct Funclet<'ll> {
64 cleanuppad: &'ll Value,
65 operand: OperandBundleDef<'ll>,
68 impl<'ll> Funclet<'ll> {
69 pub fn new(cleanuppad: &'ll Value) -> Self {
70 Funclet { cleanuppad, operand: OperandBundleDef::new("funclet", &[cleanuppad]) }
73 pub fn cleanuppad(&self) -> &'ll Value {
77 pub fn bundle(&self) -> &OperandBundleDef<'ll> {
82 impl<'ll> BackendTypes for CodegenCx<'ll, '_> {
83 type Value = &'ll Value;
84 // FIXME(eddyb) replace this with a `Function` "subclass" of `Value`.
85 type Function = &'ll Value;
87 type BasicBlock = &'ll BasicBlock;
88 type Type = &'ll Type;
89 type Funclet = Funclet<'ll>;
91 type DIScope = &'ll llvm::debuginfo::DIScope;
92 type DILocation = &'ll llvm::debuginfo::DILocation;
93 type DIVariable = &'ll llvm::debuginfo::DIVariable;
96 impl<'ll> CodegenCx<'ll, '_> {
97 pub fn const_array(&self, ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value {
98 unsafe { llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint) }
101 pub fn const_vector(&self, elts: &[&'ll Value]) -> &'ll Value {
102 unsafe { llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint) }
105 pub fn const_bytes(&self, bytes: &[u8]) -> &'ll Value {
106 bytes_in_context(self.llcx, bytes)
109 pub fn const_get_elt(&self, v: &'ll Value, idx: u64) -> &'ll Value {
111 assert_eq!(idx as c_uint as u64, idx);
112 let us = &[idx as c_uint];
113 let r = llvm::LLVMConstExtractValue(v, us.as_ptr(), us.len() as c_uint);
115 debug!("const_get_elt(v={:?}, idx={}, r={:?})", v, idx, r);
122 impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
123 fn const_null(&self, t: &'ll Type) -> &'ll Value {
124 unsafe { llvm::LLVMConstNull(t) }
127 fn const_undef(&self, t: &'ll Type) -> &'ll Value {
128 unsafe { llvm::LLVMGetUndef(t) }
131 fn const_int(&self, t: &'ll Type, i: i64) -> &'ll Value {
132 unsafe { llvm::LLVMConstInt(t, i as u64, True) }
135 fn const_uint(&self, t: &'ll Type, i: u64) -> &'ll Value {
136 unsafe { llvm::LLVMConstInt(t, i, False) }
139 fn const_uint_big(&self, t: &'ll Type, u: u128) -> &'ll Value {
141 let words = [u as u64, (u >> 64) as u64];
142 llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr())
146 fn const_bool(&self, val: bool) -> &'ll Value {
147 self.const_uint(self.type_i1(), val as u64)
150 fn const_i16(&self, i: i16) -> &'ll Value {
151 self.const_int(self.type_i16(), i as i64)
154 fn const_i32(&self, i: i32) -> &'ll Value {
155 self.const_int(self.type_i32(), i as i64)
158 fn const_u32(&self, i: u32) -> &'ll Value {
159 self.const_uint(self.type_i32(), i as u64)
162 fn const_u64(&self, i: u64) -> &'ll Value {
163 self.const_uint(self.type_i64(), i)
166 fn const_usize(&self, i: u64) -> &'ll Value {
167 let bit_size = self.data_layout().pointer_size.bits();
169 // make sure it doesn't overflow
170 assert!(i < (1 << bit_size));
173 self.const_uint(self.isize_ty, i)
176 fn const_u8(&self, i: u8) -> &'ll Value {
177 self.const_uint(self.type_i8(), i as u64)
180 fn const_real(&self, t: &'ll Type, val: f64) -> &'ll Value {
181 unsafe { llvm::LLVMConstReal(t, val) }
184 fn const_str(&self, s: Symbol) -> (&'ll Value, &'ll Value) {
185 let s_str = s.as_str();
186 let str_global = *self.const_str_cache.borrow_mut().entry(s).or_insert_with(|| {
187 let sc = self.const_bytes(s_str.as_bytes());
188 let sym = self.generate_local_symbol_name("str");
189 let g = self.define_global(&sym, self.val_ty(sc)).unwrap_or_else(|| {
190 bug!("symbol `{}` is already defined", sym);
193 llvm::LLVMSetInitializer(g, sc);
194 llvm::LLVMSetGlobalConstant(g, True);
195 llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
199 let len = s_str.len();
200 let cs = consts::ptrcast(
202 self.type_ptr_to(self.layout_of(self.tcx.types.str_).llvm_type(self)),
204 (cs, self.const_usize(len as u64))
207 fn const_struct(&self, elts: &[&'ll Value], packed: bool) -> &'ll Value {
208 struct_in_context(self.llcx, elts, packed)
211 fn const_to_opt_uint(&self, v: &'ll Value) -> Option<u64> {
212 try_as_const_integral(v).map(|v| unsafe { llvm::LLVMConstIntGetZExtValue(v) })
215 fn const_to_opt_u128(&self, v: &'ll Value, sign_ext: bool) -> Option<u128> {
216 try_as_const_integral(v).and_then(|v| unsafe {
217 let (mut lo, mut hi) = (0u64, 0u64);
218 let success = llvm::LLVMRustConstInt128Get(v, sign_ext, &mut hi, &mut lo);
219 success.then_some(hi_lo_to_u128(lo, hi))
223 fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: &'ll Type) -> &'ll Value {
224 let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
226 Scalar::Int(ScalarInt::ZST) => {
227 assert_eq!(0, layout.size(self).bytes());
228 self.const_undef(self.type_ix(0))
230 Scalar::Int(int) => {
231 let data = int.assert_bits(layout.size(self));
232 let llval = self.const_uint_big(self.type_ix(bitsize), data);
233 if layout.primitive() == Pointer {
234 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
236 self.const_bitcast(llval, llty)
239 Scalar::Ptr(ptr, _size) => {
240 let (alloc_id, offset) = ptr.into_parts();
241 let (base_addr, base_addr_space) = match self.tcx.global_alloc(alloc_id) {
242 GlobalAlloc::Memory(alloc) => {
243 let init = const_alloc_to_llvm(self, alloc);
244 let alloc = alloc.inner();
245 let value = match alloc.mutability {
246 Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
247 _ => self.static_addr_of(init, alloc.align, None),
249 if !self.sess().fewer_names() {
250 llvm::set_value_name(value, format!("{:?}", alloc_id).as_bytes());
252 (value, AddressSpace::DATA)
254 GlobalAlloc::Function(fn_instance) => (
255 self.get_fn_addr(fn_instance.polymorphize(self.tcx)),
256 self.data_layout().instruction_address_space,
258 GlobalAlloc::Static(def_id) => {
259 assert!(self.tcx.is_static(def_id));
260 assert!(!self.tcx.is_thread_local_static(def_id));
261 (self.get_static(def_id), AddressSpace::DATA)
265 llvm::LLVMRustConstInBoundsGEP2(
267 self.const_bitcast(base_addr, self.type_i8p_ext(base_addr_space)),
268 &self.const_usize(offset.bytes()),
272 if layout.primitive() != Pointer {
273 unsafe { llvm::LLVMConstPtrToInt(llval, llty) }
275 self.const_bitcast(llval, llty)
281 fn const_data_from_alloc(&self, alloc: ConstAllocation<'tcx>) -> Self::Value {
282 const_alloc_to_llvm(self, alloc)
287 layout: TyAndLayout<'tcx>,
288 alloc: ConstAllocation<'tcx>,
290 ) -> PlaceRef<'tcx, &'ll Value> {
291 let alloc_align = alloc.inner().align;
292 assert_eq!(alloc_align, layout.align.abi);
293 let llty = self.type_ptr_to(layout.llvm_type(self));
294 let llval = if layout.size == Size::ZERO {
295 let llval = self.const_usize(alloc_align.bytes());
296 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
298 let init = const_alloc_to_llvm(self, alloc);
299 let base_addr = self.static_addr_of(init, alloc_align, None);
302 llvm::LLVMRustConstInBoundsGEP2(
304 self.const_bitcast(base_addr, self.type_i8p()),
305 &self.const_usize(offset.bytes()),
309 self.const_bitcast(llval, llty)
311 PlaceRef::new_sized(llval, layout)
314 fn const_ptrcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
315 consts::ptrcast(val, ty)
319 /// Get the [LLVM type][Type] of a [`Value`].
320 pub fn val_ty(v: &Value) -> &Type {
321 unsafe { llvm::LLVMTypeOf(v) }
324 pub fn bytes_in_context<'ll>(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
326 let ptr = bytes.as_ptr() as *const c_char;
327 llvm::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True)
331 pub fn struct_in_context<'ll>(
332 llcx: &'ll llvm::Context,
337 llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), elts.len() as c_uint, packed as Bool)
342 fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
343 ((hi as u128) << 64) | (lo as u128)
346 fn try_as_const_integral(v: &Value) -> Option<&ConstantInt> {
347 unsafe { llvm::LLVMIsAConstantInt(v) }