1 // Copyright 2012-2014 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.
11 #![allow(non_camel_case_types, non_snake_case)]
13 //! Code that is useful in various codegen modules.
15 use llvm::{self, TypeKind};
16 use llvm::{True, False, Bool};
17 use rustc::hir::def_id::DefId;
18 use rustc::middle::lang_items::LangItem;
25 use type_of::LayoutLlvmExt;
26 use value::{Value, ValueTrait};
28 use rustc::ty::{self, Ty, TyCtxt};
29 use rustc::ty::layout::{HasDataLayout, LayoutOf};
31 use traits::{BuilderMethods, OperandBundleDef};
33 use libc::{c_uint, c_char};
35 use syntax::symbol::LocalInternedString;
36 use syntax_pos::{Span, DUMMY_SP};
38 pub use context::CodegenCx;
40 pub fn type_needs_drop<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> bool {
41 ty.needs_drop(tcx, ty::ParamEnv::reveal_all())
44 pub fn type_is_sized<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> bool {
45 ty.is_sized(tcx.at(DUMMY_SP), ty::ParamEnv::reveal_all())
48 pub fn type_is_freeze<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> bool {
49 ty.is_freeze(tcx, ty::ParamEnv::reveal_all(), DUMMY_SP)
53 * A note on nomenclature of linking: "extern", "foreign", and "upcall".
55 * An "extern" is an LLVM symbol we wind up emitting an undefined external
56 * reference to. This means "we don't have the thing in this compilation unit,
57 * please make sure you link it in at runtime". This could be a reference to
58 * C code found in a C library, or rust code found in a rust crate.
60 * Most "externs" are implicitly declared (automatically) as a result of a
61 * user declaring an extern _module_ dependency; this causes the rust driver
62 * to locate an extern crate, scan its compilation metadata, and emit extern
63 * declarations for any symbols used by the declaring crate.
65 * A "foreign" is an extern that references C (or other non-rust ABI) code.
66 * There is no metadata to scan for extern references so in these cases either
67 * a header-digester like bindgen, or manual function prototypes, have to
68 * serve as declarators. So these are usually given explicitly as prototype
69 * declarations, in rust code, with ABI attributes on them noting which ABI to
72 * An "upcall" is a foreign call generated by the compiler (not corresponding
73 * to any user-written call in the code) into the runtime library, to perform
74 * some helper task such as bringing a task to life, allocating memory, etc.
78 /// A structure representing an active landing pad for the duration of a basic
81 /// Each `Block` may contain an instance of this, indicating whether the block
82 /// is part of a landing pad or not. This is used to make decision about whether
83 /// to emit `invoke` instructions (e.g. in a landing pad we don't continue to
84 /// use `invoke`) and also about various function call metadata.
86 /// For GNU exceptions (`landingpad` + `resume` instructions) this structure is
87 /// just a bunch of `None` instances (not too interesting), but for MSVC
88 /// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data.
89 /// When inside of a landing pad, each function call in LLVM IR needs to be
90 /// annotated with which landing pad it's a part of. This is accomplished via
91 /// the `OperandBundleDef` value created for MSVC landing pads.
92 pub struct Funclet<'ll> {
93 cleanuppad: &'ll Value,
94 operand: OperandBundleDef<'ll, &'ll Value>,
98 pub fn new(cleanuppad: &'ll Value) -> Self {
101 operand: OperandBundleDef::new("funclet", cleanuppad),
105 pub fn cleanuppad(&self) -> &'ll Value {
109 pub fn bundle(&self) -> &OperandBundleDef<'ll, &'ll Value> {
114 pub fn val_ty<Value : ?Sized>(v: &'ll Value) -> &'ll Type where Value : ValueTrait {
116 llvm::LLVMTypeOf(v.to_llvm())
120 // LLVM constant constructors.
121 pub fn C_null(t: &'ll Type) -> &'ll Value {
123 llvm::LLVMConstNull(t)
127 pub fn C_undef<Value : ?Sized>(t: &'ll Type) -> &'ll Value where Value : ValueTrait {
129 Value::of_llvm(llvm::LLVMGetUndef(t))
133 pub fn C_int<Value : ?Sized>(t: &'ll Type, i: i64) -> &'ll Value where Value : ValueTrait {
135 Value::of_llvm(llvm::LLVMConstInt(t, i as u64, True))
139 pub fn C_uint<Value : ?Sized>(t: &'ll Type, i: u64) -> &'ll Value where Value : ValueTrait {
141 Value::of_llvm(llvm::LLVMConstInt(t, i, False))
145 pub fn C_uint_big(t: &'ll Type, u: u128) -> &'ll Value {
147 let words = [u as u64, (u >> 64) as u64];
148 llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr())
152 pub fn C_bool<Value : ?Sized>(
153 cx: &CodegenCx<'ll, '_, &'ll Value>,
155 ) -> &'ll Value where Value : ValueTrait {
156 C_uint(Type::i1(cx), val as u64)
159 pub fn C_i32<Value : ?Sized>(
160 cx: &CodegenCx<'ll, '_, &'ll Value>,
162 ) -> &'ll Value where Value : ValueTrait {
163 C_int(Type::i32(cx), i as i64)
166 pub fn C_u32(cx: &CodegenCx<'ll, '_>, i: u32) -> &'ll Value {
167 C_uint(Type::i32(cx), i as u64)
170 pub fn C_u64(cx: &CodegenCx<'ll, '_>, i: u64) -> &'ll Value {
171 C_uint(Type::i64(cx), i)
174 pub fn C_usize<Value : ?Sized>(
175 cx: &CodegenCx<'ll, '_, &'ll Value>,
177 ) -> &'ll Value where Value : ValueTrait {
178 let bit_size = cx.data_layout().pointer_size.bits();
180 // make sure it doesn't overflow
181 assert!(i < (1<<bit_size));
184 C_uint(cx.isize_ty, i)
187 pub fn C_u8(cx: &CodegenCx<'ll, '_>, i: u8) -> &'ll Value {
188 C_uint(Type::i8(cx), i as u64)
192 // This is a 'c-like' raw string, which differs from
193 // our boxed-and-length-annotated strings.
195 cx: &CodegenCx<'ll, '_>,
196 s: LocalInternedString,
197 null_terminated: bool,
200 if let Some(&llval) = cx.const_cstr_cache.borrow().get(&s) {
204 let sc = llvm::LLVMConstStringInContext(cx.llcx,
205 s.as_ptr() as *const c_char,
207 !null_terminated as Bool);
208 let sym = cx.generate_local_symbol_name("str");
209 let g = declare::define_global(cx, &sym[..], val_ty(sc)).unwrap_or_else(||{
210 bug!("symbol `{}` is already defined", sym);
212 llvm::LLVMSetInitializer(g, sc);
213 llvm::LLVMSetGlobalConstant(g, True);
214 llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
216 cx.const_cstr_cache.borrow_mut().insert(s, g);
221 // NB: Do not use `do_spill_noroot` to make this into a constant string, or
222 // you will be kicked off fast isel. See issue #4352 for an example of this.
223 pub fn C_str_slice(cx: &CodegenCx<'ll, '_>, s: LocalInternedString) -> &'ll Value {
225 let cs = consts::ptrcast(C_cstr(cx, s, false),
226 cx.layout_of(cx.tcx.mk_str()).llvm_type(cx).ptr_to());
227 C_fat_ptr(cx, cs, C_usize(cx, len as u64))
230 pub fn C_fat_ptr(cx: &CodegenCx<'ll, '_>, ptr: &'ll Value, meta: &'ll Value) -> &'ll Value {
231 assert_eq!(abi::FAT_PTR_ADDR, 0);
232 assert_eq!(abi::FAT_PTR_EXTRA, 1);
233 C_struct(cx, &[ptr, meta], false)
236 pub fn C_struct(cx: &CodegenCx<'ll, '_>, elts: &[&'ll Value], packed: bool) -> &'ll Value {
237 C_struct_in_context(cx.llcx, elts, packed)
240 pub fn C_struct_in_context(
241 llcx: &'ll llvm::Context,
246 llvm::LLVMConstStructInContext(llcx,
247 elts.as_ptr(), elts.len() as c_uint,
252 pub fn C_array(ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value {
254 return llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint);
258 pub fn C_vector(elts: &[&'ll Value]) -> &'ll Value {
260 return llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint);
264 pub fn C_bytes(cx: &CodegenCx<'ll, '_>, bytes: &[u8]) -> &'ll Value {
265 C_bytes_in_context(cx.llcx, bytes)
268 pub fn C_bytes_in_context(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
270 let ptr = bytes.as_ptr() as *const c_char;
271 return llvm::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True);
275 pub fn const_get_elt(v: &'ll Value, idx: u64) -> &'ll Value {
277 assert_eq!(idx as c_uint as u64, idx);
278 let us = &[idx as c_uint];
279 let r = llvm::LLVMConstExtractValue(v, us.as_ptr(), us.len() as c_uint);
281 debug!("const_get_elt(v={:?}, idx={}, r={:?})",
288 pub fn const_get_real(v: &'ll Value) -> Option<(f64, bool)> {
290 if is_const_real(v) {
291 let mut loses_info: llvm::Bool = ::std::mem::uninitialized();
292 let r = llvm::LLVMConstRealGetDouble(v, &mut loses_info);
293 let loses_info = if loses_info == 1 { true } else { false };
294 Some((r, loses_info))
301 pub fn const_to_uint(v: &'ll Value) -> u64 {
303 llvm::LLVMConstIntGetZExtValue(v)
307 pub fn is_const_integral(v: &'ll Value) -> bool {
309 llvm::LLVMIsAConstantInt(v).is_some()
313 pub fn is_const_real(v: &'ll Value) -> bool {
315 llvm::LLVMIsAConstantFP(v).is_some()
321 fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
322 ((hi as u128) << 64) | (lo as u128)
325 pub fn const_to_opt_u128(v: &'ll Value, sign_ext: bool) -> Option<u128> {
327 if is_const_integral(v) {
328 let (mut lo, mut hi) = (0u64, 0u64);
329 let success = llvm::LLVMRustConstInt128Get(v, sign_ext,
332 Some(hi_lo_to_u128(lo, hi))
342 pub fn langcall(tcx: TyCtxt,
347 tcx.lang_items().require(li).unwrap_or_else(|s| {
348 let msg = format!("{} {}", msg, s);
350 Some(span) => tcx.sess.span_fatal(span, &msg[..]),
351 None => tcx.sess.fatal(&msg[..]),
356 // To avoid UB from LLVM, these two functions mask RHS with an
357 // appropriate mask unconditionally (i.e. the fallback behavior for
358 // all shifts). For 32- and 64-bit types, this matches the semantics
359 // of Java. (See related discussion on #1877 and #10183.)
361 pub fn build_unchecked_lshift(
362 bx: &Builder<'a, 'll, 'tcx>,
366 let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shl, lhs, rhs);
367 // #1877, #10183: Ensure that input is always valid
368 let rhs = shift_mask_rhs(bx, rhs);
372 pub fn build_unchecked_rshift(
373 bx: &Builder<'a, 'll, 'tcx>, lhs_t: Ty<'tcx>, lhs: &'ll Value, rhs: &'ll Value
375 let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shr, lhs, rhs);
376 // #1877, #10183: Ensure that input is always valid
377 let rhs = shift_mask_rhs(bx, rhs);
378 let is_signed = lhs_t.is_signed();
386 fn shift_mask_rhs(bx: &Builder<'a, 'll, 'tcx>, rhs: &'ll Value) -> &'ll Value {
387 let rhs_llty = val_ty(rhs);
388 bx.and(rhs, shift_mask_val(bx, rhs_llty, rhs_llty, false))
391 pub fn shift_mask_val(
392 bx: &Builder<'a, 'll, 'tcx>,
394 mask_llty: &'ll Type,
397 let kind = llty.kind();
399 TypeKind::Integer => {
400 // i8/u8 can shift by at most 7, i16/u16 by at most 15, etc.
401 let val = llty.int_width() - 1;
403 C_int(mask_llty, !val as i64)
405 C_uint(mask_llty, val)
408 TypeKind::Vector => {
409 let mask = shift_mask_val(bx, llty.element_type(), mask_llty.element_type(), invert);
410 bx.vector_splat(mask_llty.vector_length(), mask)
412 _ => bug!("shift_mask_val: expected Integer or Vector, found {:?}", kind),