1 #![allow(non_camel_case_types, non_snake_case)]
3 //! Code that is useful in various codegen modules.
6 use crate::llvm::{self, BasicBlock, Bool, ConstantInt, False, OperandBundleDef, True};
7 use crate::type_::Type;
8 use crate::type_of::LayoutLlvmExt;
9 use crate::value::Value;
12 use rustc_codegen_ssa::traits::*;
14 use crate::consts::const_alloc_to_llvm;
15 use rustc::mir::interpret::{Allocation, GlobalAlloc, Scalar};
16 use rustc::ty::layout::{self, HasDataLayout, LayoutOf, Size, TyLayout};
17 use rustc_codegen_ssa::mir::place::PlaceRef;
19 use libc::{c_char, c_uint};
21 use rustc_span::symbol::Symbol;
22 use syntax::ast::Mutability;
24 pub use crate::context::CodegenCx;
27 * A note on nomenclature of linking: "extern", "foreign", and "upcall".
29 * An "extern" is an LLVM symbol we wind up emitting an undefined external
30 * reference to. This means "we don't have the thing in this compilation unit,
31 * please make sure you link it in at runtime". This could be a reference to
32 * C code found in a C library, or rust code found in a rust crate.
34 * Most "externs" are implicitly declared (automatically) as a result of a
35 * user declaring an extern _module_ dependency; this causes the rust driver
36 * to locate an extern crate, scan its compilation metadata, and emit extern
37 * declarations for any symbols used by the declaring crate.
39 * A "foreign" is an extern that references C (or other non-rust ABI) code.
40 * There is no metadata to scan for extern references so in these cases either
41 * a header-digester like bindgen, or manual function prototypes, have to
42 * serve as declarators. So these are usually given explicitly as prototype
43 * declarations, in rust code, with ABI attributes on them noting which ABI to
46 * An "upcall" is a foreign call generated by the compiler (not corresponding
47 * to any user-written call in the code) into the runtime library, to perform
48 * some helper task such as bringing a task to life, allocating memory, etc.
52 /// A structure representing an active landing pad for the duration of a basic
55 /// Each `Block` may contain an instance of this, indicating whether the block
56 /// is part of a landing pad or not. This is used to make decision about whether
57 /// to emit `invoke` instructions (e.g., in a landing pad we don't continue to
58 /// use `invoke`) and also about various function call metadata.
60 /// For GNU exceptions (`landingpad` + `resume` instructions) this structure is
61 /// just a bunch of `None` instances (not too interesting), but for MSVC
62 /// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data.
63 /// When inside of a landing pad, each function call in LLVM IR needs to be
64 /// annotated with which landing pad it's a part of. This is accomplished via
65 /// the `OperandBundleDef` value created for MSVC landing pads.
66 pub struct Funclet<'ll> {
67 cleanuppad: &'ll Value,
68 operand: OperandBundleDef<'ll>,
72 pub fn new(cleanuppad: &'ll Value) -> Self {
73 Funclet { cleanuppad, operand: OperandBundleDef::new("funclet", &[cleanuppad]) }
76 pub fn cleanuppad(&self) -> &'ll Value {
80 pub fn bundle(&self) -> &OperandBundleDef<'ll> {
85 impl BackendTypes for CodegenCx<'ll, 'tcx> {
86 type Value = &'ll Value;
87 type Function = &'ll Value;
89 type BasicBlock = &'ll BasicBlock;
90 type Type = &'ll Type;
91 type Funclet = Funclet<'ll>;
93 type DIScope = &'ll llvm::debuginfo::DIScope;
96 impl CodegenCx<'ll, 'tcx> {
97 pub fn const_array(&self, ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value {
99 return llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint);
103 pub fn const_vector(&self, elts: &[&'ll Value]) -> &'ll Value {
105 return llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint);
109 pub fn const_bytes(&self, bytes: &[u8]) -> &'ll Value {
110 bytes_in_context(self.llcx, bytes)
113 fn const_cstr(&self, s: Symbol, null_terminated: bool) -> &'ll Value {
115 if let Some(&llval) = self.const_cstr_cache.borrow().get(&s) {
119 let s_str = s.as_str();
120 let sc = llvm::LLVMConstStringInContext(
122 s_str.as_ptr() as *const c_char,
123 s_str.len() as c_uint,
124 !null_terminated as Bool,
126 let sym = self.generate_local_symbol_name("str");
127 let g = self.define_global(&sym[..], self.val_ty(sc)).unwrap_or_else(|| {
128 bug!("symbol `{}` is already defined", sym);
130 llvm::LLVMSetInitializer(g, sc);
131 llvm::LLVMSetGlobalConstant(g, True);
132 llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
134 self.const_cstr_cache.borrow_mut().insert(s, g);
139 pub fn const_get_elt(&self, v: &'ll Value, idx: u64) -> &'ll Value {
141 assert_eq!(idx as c_uint as u64, idx);
142 let us = &[idx as c_uint];
143 let r = llvm::LLVMConstExtractValue(v, us.as_ptr(), us.len() as c_uint);
145 debug!("const_get_elt(v={:?}, idx={}, r={:?})", v, idx, r);
152 impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
153 fn const_null(&self, t: &'ll Type) -> &'ll Value {
154 unsafe { llvm::LLVMConstNull(t) }
157 fn const_undef(&self, t: &'ll Type) -> &'ll Value {
158 unsafe { llvm::LLVMGetUndef(t) }
161 fn const_int(&self, t: &'ll Type, i: i64) -> &'ll Value {
162 unsafe { llvm::LLVMConstInt(t, i as u64, True) }
165 fn const_uint(&self, t: &'ll Type, i: u64) -> &'ll Value {
166 unsafe { llvm::LLVMConstInt(t, i, False) }
169 fn const_uint_big(&self, t: &'ll Type, u: u128) -> &'ll Value {
171 let words = [u as u64, (u >> 64) as u64];
172 llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr())
176 fn const_bool(&self, val: bool) -> &'ll Value {
177 self.const_uint(self.type_i1(), val as u64)
180 fn const_i32(&self, i: i32) -> &'ll Value {
181 self.const_int(self.type_i32(), i as i64)
184 fn const_u32(&self, i: u32) -> &'ll Value {
185 self.const_uint(self.type_i32(), i as u64)
188 fn const_u64(&self, i: u64) -> &'ll Value {
189 self.const_uint(self.type_i64(), i)
192 fn const_usize(&self, i: u64) -> &'ll Value {
193 let bit_size = self.data_layout().pointer_size.bits();
195 // make sure it doesn't overflow
196 assert!(i < (1 << bit_size));
199 self.const_uint(self.isize_ty, i)
202 fn const_u8(&self, i: u8) -> &'ll Value {
203 self.const_uint(self.type_i8(), i as u64)
206 fn const_real(&self, t: &'ll Type, val: f64) -> &'ll Value {
207 unsafe { llvm::LLVMConstReal(t, val) }
210 fn const_str(&self, s: Symbol) -> (&'ll Value, &'ll Value) {
211 let len = s.as_str().len();
212 let cs = consts::ptrcast(
213 self.const_cstr(s, false),
214 self.type_ptr_to(self.layout_of(self.tcx.mk_str()).llvm_type(self)),
216 (cs, self.const_usize(len as u64))
219 fn const_struct(&self, elts: &[&'ll Value], packed: bool) -> &'ll Value {
220 struct_in_context(self.llcx, elts, packed)
223 fn const_to_opt_uint(&self, v: &'ll Value) -> Option<u64> {
224 try_as_const_integral(v).map(|v| unsafe { llvm::LLVMConstIntGetZExtValue(v) })
227 fn const_to_opt_u128(&self, v: &'ll Value, sign_ext: bool) -> Option<u128> {
228 try_as_const_integral(v).and_then(|v| unsafe {
229 let (mut lo, mut hi) = (0u64, 0u64);
230 let success = llvm::LLVMRustConstInt128Get(v, sign_ext, &mut hi, &mut lo);
231 success.then_some(hi_lo_to_u128(lo, hi))
235 fn scalar_to_backend(
238 layout: &layout::Scalar,
241 let bitsize = if layout.is_bool() { 1 } else { layout.value.size(self).bits() };
243 Scalar::Raw { size: 0, .. } => {
244 assert_eq!(0, layout.value.size(self).bytes());
245 self.const_undef(self.type_ix(0))
247 Scalar::Raw { data, size } => {
248 assert_eq!(size as u64, layout.value.size(self).bytes());
249 let llval = self.const_uint_big(self.type_ix(bitsize), data);
250 if layout.value == layout::Pointer {
251 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
253 self.const_bitcast(llval, llty)
256 Scalar::Ptr(ptr) => {
257 let alloc_kind = self.tcx.alloc_map.lock().get(ptr.alloc_id);
258 let base_addr = match alloc_kind {
259 Some(GlobalAlloc::Memory(alloc)) => {
260 let init = const_alloc_to_llvm(self, alloc);
261 if alloc.mutability == Mutability::Mut {
262 self.static_addr_of_mut(init, alloc.align, None)
264 self.static_addr_of(init, alloc.align, None)
267 Some(GlobalAlloc::Function(fn_instance)) => self.get_fn_addr(fn_instance),
268 Some(GlobalAlloc::Static(def_id)) => {
269 assert!(self.tcx.is_static(def_id));
270 self.get_static(def_id)
272 None => bug!("missing allocation {:?}", ptr.alloc_id),
275 llvm::LLVMConstInBoundsGEP(
276 self.const_bitcast(base_addr, self.type_i8p()),
277 &self.const_usize(ptr.offset.bytes()),
281 if layout.value != layout::Pointer {
282 unsafe { llvm::LLVMConstPtrToInt(llval, llty) }
284 self.const_bitcast(llval, llty)
292 layout: TyLayout<'tcx>,
295 ) -> PlaceRef<'tcx, &'ll Value> {
296 assert_eq!(alloc.align, layout.align.abi);
297 let llty = self.type_ptr_to(layout.llvm_type(self));
298 let llval = if layout.size == Size::ZERO {
299 let llval = self.const_usize(alloc.align.bytes());
300 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
302 let init = const_alloc_to_llvm(self, alloc);
303 let base_addr = self.static_addr_of(init, alloc.align, None);
306 llvm::LLVMConstInBoundsGEP(
307 self.const_bitcast(base_addr, self.type_i8p()),
308 &self.const_usize(offset.bytes()),
312 self.const_bitcast(llval, llty)
314 PlaceRef::new_sized(llval, layout)
317 fn const_ptrcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
318 consts::ptrcast(val, ty)
322 pub fn val_ty(v: &'ll Value) -> &'ll Type {
323 unsafe { llvm::LLVMTypeOf(v) }
326 pub fn bytes_in_context(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
328 let ptr = bytes.as_ptr() as *const c_char;
329 return llvm::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True);
333 pub fn struct_in_context(llcx: &'a llvm::Context, elts: &[&'a Value], packed: bool) -> &'a Value {
335 llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), elts.len() as c_uint, packed as Bool)
340 fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
341 ((hi as u128) << 64) | (lo as u128)
344 fn try_as_const_integral(v: &'ll Value) -> Option<&'ll ConstantInt> {
345 unsafe { llvm::LLVMIsAConstantInt(v) }