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_target::abi::{self, AddressSpace, HasDataLayout, Pointer, Size};
18 use libc::{c_char, c_uint};
22 * A note on nomenclature of linking: "extern", "foreign", and "upcall".
24 * An "extern" is an LLVM symbol we wind up emitting an undefined external
25 * reference to. This means "we don't have the thing in this compilation unit,
26 * please make sure you link it in at runtime". This could be a reference to
27 * C code found in a C library, or rust code found in a rust crate.
29 * Most "externs" are implicitly declared (automatically) as a result of a
30 * user declaring an extern _module_ dependency; this causes the rust driver
31 * to locate an extern crate, scan its compilation metadata, and emit extern
32 * declarations for any symbols used by the declaring crate.
34 * A "foreign" is an extern that references C (or other non-rust ABI) code.
35 * There is no metadata to scan for extern references so in these cases either
36 * a header-digester like bindgen, or manual function prototypes, have to
37 * serve as declarators. So these are usually given explicitly as prototype
38 * declarations, in rust code, with ABI attributes on them noting which ABI to
41 * An "upcall" is a foreign call generated by the compiler (not corresponding
42 * to any user-written call in the code) into the runtime library, to perform
43 * some helper task such as bringing a task to life, allocating memory, etc.
47 /// A structure representing an active landing pad for the duration of a basic
50 /// Each `Block` may contain an instance of this, indicating whether the block
51 /// is part of a landing pad or not. This is used to make decision about whether
52 /// to emit `invoke` instructions (e.g., in a landing pad we don't continue to
53 /// use `invoke`) and also about various function call metadata.
55 /// For GNU exceptions (`landingpad` + `resume` instructions) this structure is
56 /// just a bunch of `None` instances (not too interesting), but for MSVC
57 /// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data.
58 /// When inside of a landing pad, each function call in LLVM IR needs to be
59 /// annotated with which landing pad it's a part of. This is accomplished via
60 /// the `OperandBundleDef` value created for MSVC landing pads.
61 pub struct Funclet<'ll> {
62 cleanuppad: &'ll Value,
63 operand: OperandBundleDef<'ll>,
66 impl<'ll> Funclet<'ll> {
67 pub fn new(cleanuppad: &'ll Value) -> Self {
68 Funclet { cleanuppad, operand: OperandBundleDef::new("funclet", &[cleanuppad]) }
71 pub fn cleanuppad(&self) -> &'ll Value {
75 pub fn bundle(&self) -> &OperandBundleDef<'ll> {
80 impl<'ll> BackendTypes for CodegenCx<'ll, '_> {
81 type Value = &'ll Value;
82 // FIXME(eddyb) replace this with a `Function` "subclass" of `Value`.
83 type Function = &'ll Value;
85 type BasicBlock = &'ll BasicBlock;
86 type Type = &'ll Type;
87 type Funclet = Funclet<'ll>;
89 type DIScope = &'ll llvm::debuginfo::DIScope;
90 type DILocation = &'ll llvm::debuginfo::DILocation;
91 type DIVariable = &'ll llvm::debuginfo::DIVariable;
94 impl<'ll> CodegenCx<'ll, '_> {
95 pub fn const_array(&self, ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value {
96 unsafe { llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint) }
99 pub fn const_vector(&self, elts: &[&'ll Value]) -> &'ll Value {
100 unsafe { llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint) }
103 pub fn const_bytes(&self, bytes: &[u8]) -> &'ll Value {
104 bytes_in_context(self.llcx, bytes)
107 pub fn const_get_elt(&self, v: &'ll Value, idx: u64) -> &'ll Value {
109 assert_eq!(idx as c_uint as u64, idx);
110 let r = llvm::LLVMGetAggregateElement(v, idx as c_uint).unwrap();
112 debug!("const_get_elt(v={:?}, idx={}, r={:?})", v, idx, r);
119 impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
120 fn const_null(&self, t: &'ll Type) -> &'ll Value {
121 unsafe { llvm::LLVMConstNull(t) }
124 fn const_undef(&self, t: &'ll Type) -> &'ll Value {
125 unsafe { llvm::LLVMGetUndef(t) }
128 fn const_int(&self, t: &'ll Type, i: i64) -> &'ll Value {
129 unsafe { llvm::LLVMConstInt(t, i as u64, True) }
132 fn const_uint(&self, t: &'ll Type, i: u64) -> &'ll Value {
133 unsafe { llvm::LLVMConstInt(t, i, False) }
136 fn const_uint_big(&self, t: &'ll Type, u: u128) -> &'ll Value {
138 let words = [u as u64, (u >> 64) as u64];
139 llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr())
143 fn const_bool(&self, val: bool) -> &'ll Value {
144 self.const_uint(self.type_i1(), val as u64)
147 fn const_i16(&self, i: i16) -> &'ll Value {
148 self.const_int(self.type_i16(), i as i64)
151 fn const_i32(&self, i: i32) -> &'ll Value {
152 self.const_int(self.type_i32(), i as i64)
155 fn const_u32(&self, i: u32) -> &'ll Value {
156 self.const_uint(self.type_i32(), i as u64)
159 fn const_u64(&self, i: u64) -> &'ll Value {
160 self.const_uint(self.type_i64(), i)
163 fn const_usize(&self, i: u64) -> &'ll Value {
164 let bit_size = self.data_layout().pointer_size.bits();
166 // make sure it doesn't overflow
167 assert!(i < (1 << bit_size));
170 self.const_uint(self.isize_ty, i)
173 fn const_u8(&self, i: u8) -> &'ll Value {
174 self.const_uint(self.type_i8(), i as u64)
177 fn const_real(&self, t: &'ll Type, val: f64) -> &'ll Value {
178 unsafe { llvm::LLVMConstReal(t, val) }
181 fn const_str(&self, s: &str) -> (&'ll Value, &'ll Value) {
182 let str_global = *self
188 let sc = self.const_bytes(s.as_bytes());
189 let sym = self.generate_local_symbol_name("str");
190 let g = self.define_global(&sym, self.val_ty(sc)).unwrap_or_else(|| {
191 bug!("symbol `{}` is already defined", sym);
194 llvm::LLVMSetInitializer(g, sc);
195 llvm::LLVMSetGlobalConstant(g, True);
196 llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
202 let cs = consts::ptrcast(
204 self.type_ptr_to(self.layout_of(self.tcx.types.str_).llvm_type(self)),
206 (cs, self.const_usize(len as u64))
209 fn const_struct(&self, elts: &[&'ll Value], packed: bool) -> &'ll Value {
210 struct_in_context(self.llcx, elts, packed)
213 fn const_to_opt_uint(&self, v: &'ll Value) -> Option<u64> {
214 try_as_const_integral(v).map(|v| unsafe { llvm::LLVMConstIntGetZExtValue(v) })
217 fn const_to_opt_u128(&self, v: &'ll Value, sign_ext: bool) -> Option<u128> {
218 try_as_const_integral(v).and_then(|v| unsafe {
219 let (mut lo, mut hi) = (0u64, 0u64);
220 let success = llvm::LLVMRustConstInt128Get(v, sign_ext, &mut hi, &mut lo);
221 success.then_some(hi_lo_to_u128(lo, hi))
225 fn zst_to_backend(&self, _llty: &'ll Type) -> &'ll Value {
226 self.const_undef(self.type_ix(0))
229 fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: &'ll Type) -> &'ll Value {
230 let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
232 Scalar::Int(int) => {
233 let data = int.assert_bits(layout.size(self));
234 let llval = self.const_uint_big(self.type_ix(bitsize), data);
235 if layout.primitive() == Pointer {
236 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
238 self.const_bitcast(llval, llty)
241 Scalar::Ptr(ptr, _size) => {
242 let (alloc_id, offset) = ptr.into_parts();
243 let (base_addr, base_addr_space) = match self.tcx.global_alloc(alloc_id) {
244 GlobalAlloc::Memory(alloc) => {
245 let init = const_alloc_to_llvm(self, alloc);
246 let alloc = alloc.inner();
247 let value = match alloc.mutability {
248 Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
249 _ => self.static_addr_of(init, alloc.align, None),
251 if !self.sess().fewer_names() {
252 llvm::set_value_name(value, format!("{:?}", alloc_id).as_bytes());
254 (value, AddressSpace::DATA)
256 GlobalAlloc::Function(fn_instance) => (
257 self.get_fn_addr(fn_instance.polymorphize(self.tcx)),
258 self.data_layout().instruction_address_space,
260 GlobalAlloc::VTable(ty, trait_ref) => {
263 .global_alloc(self.tcx.vtable_allocation((ty, trait_ref)))
265 let init = const_alloc_to_llvm(self, alloc);
266 let value = self.static_addr_of(init, alloc.inner().align, None);
267 (value, AddressSpace::DATA)
269 GlobalAlloc::Static(def_id) => {
270 assert!(self.tcx.is_static(def_id));
271 assert!(!self.tcx.is_thread_local_static(def_id));
272 (self.get_static(def_id), AddressSpace::DATA)
276 llvm::LLVMRustConstInBoundsGEP2(
278 self.const_bitcast(base_addr, self.type_i8p_ext(base_addr_space)),
279 &self.const_usize(offset.bytes()),
283 if layout.primitive() != Pointer {
284 unsafe { llvm::LLVMConstPtrToInt(llval, llty) }
286 self.const_bitcast(llval, llty)
292 fn const_data_from_alloc(&self, alloc: ConstAllocation<'tcx>) -> Self::Value {
293 const_alloc_to_llvm(self, alloc)
298 layout: TyAndLayout<'tcx>,
299 alloc: ConstAllocation<'tcx>,
301 ) -> PlaceRef<'tcx, &'ll Value> {
302 let alloc_align = alloc.inner().align;
303 assert_eq!(alloc_align, layout.align.abi);
304 let llty = self.type_ptr_to(layout.llvm_type(self));
305 let llval = if layout.size == Size::ZERO {
306 let llval = self.const_usize(alloc_align.bytes());
307 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
309 let init = const_alloc_to_llvm(self, alloc);
310 let base_addr = self.static_addr_of(init, alloc_align, None);
313 llvm::LLVMRustConstInBoundsGEP2(
315 self.const_bitcast(base_addr, self.type_i8p()),
316 &self.const_usize(offset.bytes()),
320 self.const_bitcast(llval, llty)
322 PlaceRef::new_sized(llval, layout)
325 fn const_ptrcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
326 consts::ptrcast(val, ty)
330 /// Get the [LLVM type][Type] of a [`Value`].
331 pub fn val_ty(v: &Value) -> &Type {
332 unsafe { llvm::LLVMTypeOf(v) }
335 pub fn bytes_in_context<'ll>(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
337 let ptr = bytes.as_ptr() as *const c_char;
338 llvm::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True)
342 pub fn struct_in_context<'ll>(
343 llcx: &'ll llvm::Context,
348 llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), elts.len() as c_uint, packed as Bool)
353 fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
354 ((hi as u128) << 64) | (lo as u128)
357 fn try_as_const_integral(v: &Value) -> Option<&ConstantInt> {
358 unsafe { llvm::LLVMIsAConstantInt(v) }