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, OperandBundleDef};
17 use rustc::hir::def_id::DefId;
18 use rustc::middle::lang_items::LangItem;
25 use type_of::LayoutLlvmExt;
28 use rustc::ty::{self, Ty, TyCtxt};
29 use rustc::ty::layout::{HasDataLayout, LayoutOf};
32 use libc::{c_uint, c_char};
34 use syntax::symbol::LocalInternedString;
35 use syntax_pos::{Span, DUMMY_SP};
37 pub use context::CodegenCx;
39 pub fn type_needs_drop<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> bool {
40 ty.needs_drop(tcx, ty::ParamEnv::reveal_all())
43 pub fn type_is_sized<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> bool {
44 ty.is_sized(tcx.at(DUMMY_SP), ty::ParamEnv::reveal_all())
47 pub fn type_is_freeze<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> bool {
48 ty.is_freeze(tcx, ty::ParamEnv::reveal_all(), DUMMY_SP)
52 * A note on nomenclature of linking: "extern", "foreign", and "upcall".
54 * An "extern" is an LLVM symbol we wind up emitting an undefined external
55 * reference to. This means "we don't have the thing in this compilation unit,
56 * please make sure you link it in at runtime". This could be a reference to
57 * C code found in a C library, or rust code found in a rust crate.
59 * Most "externs" are implicitly declared (automatically) as a result of a
60 * user declaring an extern _module_ dependency; this causes the rust driver
61 * to locate an extern crate, scan its compilation metadata, and emit extern
62 * declarations for any symbols used by the declaring crate.
64 * A "foreign" is an extern that references C (or other non-rust ABI) code.
65 * There is no metadata to scan for extern references so in these cases either
66 * a header-digester like bindgen, or manual function prototypes, have to
67 * serve as declarators. So these are usually given explicitly as prototype
68 * declarations, in rust code, with ABI attributes on them noting which ABI to
71 * An "upcall" is a foreign call generated by the compiler (not corresponding
72 * to any user-written call in the code) into the runtime library, to perform
73 * some helper task such as bringing a task to life, allocating memory, etc.
77 /// A structure representing an active landing pad for the duration of a basic
80 /// Each `Block` may contain an instance of this, indicating whether the block
81 /// is part of a landing pad or not. This is used to make decision about whether
82 /// to emit `invoke` instructions (e.g. in a landing pad we don't continue to
83 /// use `invoke`) and also about various function call metadata.
85 /// For GNU exceptions (`landingpad` + `resume` instructions) this structure is
86 /// just a bunch of `None` instances (not too interesting), but for MSVC
87 /// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data.
88 /// When inside of a landing pad, each function call in LLVM IR needs to be
89 /// annotated with which landing pad it's a part of. This is accomplished via
90 /// the `OperandBundleDef` value created for MSVC landing pads.
91 pub struct Funclet<'ll> {
92 cleanuppad: &'ll Value,
93 operand: OperandBundleDef<'ll>,
97 pub fn new(cleanuppad: &'ll Value) -> Self {
100 operand: OperandBundleDef::new("funclet", &[cleanuppad]),
104 pub fn cleanuppad(&self) -> &'ll Value {
108 pub fn bundle(&self) -> &OperandBundleDef<'ll> {
113 pub fn val_ty(v: &'ll Value) -> &'ll Type {
119 // LLVM constant constructors.
120 pub fn C_null(t: &'ll Type) -> &'ll Value {
122 llvm::LLVMConstNull(t)
126 pub fn C_undef(t: &'ll Type) -> &'ll Value {
128 llvm::LLVMGetUndef(t)
132 pub fn C_int(t: &'ll Type, i: i64) -> &'ll Value {
134 llvm::LLVMConstInt(t, i as u64, True)
138 pub fn C_uint(t: &'ll Type, i: u64) -> &'ll Value {
140 llvm::LLVMConstInt(t, i, False)
144 pub fn C_uint_big(t: &'ll Type, u: u128) -> &'ll Value {
146 let words = [u as u64, (u >> 64) as u64];
147 llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr())
151 pub fn C_bool(cx: &CodegenCx<'ll, '_>, val: bool) -> &'ll Value {
152 C_uint(Type::i1(cx), val as u64)
155 pub fn C_i32(cx: &CodegenCx<'ll, '_>, i: i32) -> &'ll Value {
156 C_int(Type::i32(cx), i as i64)
159 pub fn C_u32(cx: &CodegenCx<'ll, '_>, i: u32) -> &'ll Value {
160 C_uint(Type::i32(cx), i as u64)
163 pub fn C_u64(cx: &CodegenCx<'ll, '_>, i: u64) -> &'ll Value {
164 C_uint(Type::i64(cx), i)
167 pub fn C_usize(cx: &CodegenCx<'ll, '_>, i: u64) -> &'ll Value {
168 let bit_size = cx.data_layout().pointer_size.bits();
170 // make sure it doesn't overflow
171 assert!(i < (1<<bit_size));
174 C_uint(cx.isize_ty, i)
177 pub fn C_u8(cx: &CodegenCx<'ll, '_>, i: u8) -> &'ll Value {
178 C_uint(Type::i8(cx), i as u64)
182 // This is a 'c-like' raw string, which differs from
183 // our boxed-and-length-annotated strings.
185 cx: &CodegenCx<'ll, '_>,
186 s: LocalInternedString,
187 null_terminated: bool,
190 if let Some(&llval) = cx.const_cstr_cache.borrow().get(&s) {
194 let sc = llvm::LLVMConstStringInContext(cx.llcx,
195 s.as_ptr() as *const c_char,
197 !null_terminated as Bool);
198 let sym = cx.generate_local_symbol_name("str");
199 let g = declare::define_global(cx, &sym[..], val_ty(sc)).unwrap_or_else(||{
200 bug!("symbol `{}` is already defined", sym);
202 llvm::LLVMSetInitializer(g, sc);
203 llvm::LLVMSetGlobalConstant(g, True);
204 llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
206 cx.const_cstr_cache.borrow_mut().insert(s, g);
211 // NB: Do not use `do_spill_noroot` to make this into a constant string, or
212 // you will be kicked off fast isel. See issue #4352 for an example of this.
213 pub fn C_str_slice(cx: &CodegenCx<'ll, '_>, s: LocalInternedString) -> &'ll Value {
215 let cs = consts::ptrcast(C_cstr(cx, s, false),
216 cx.layout_of(cx.tcx.mk_str()).llvm_type(cx).ptr_to());
217 C_fat_ptr(cx, cs, C_usize(cx, len as u64))
220 pub fn C_fat_ptr(cx: &CodegenCx<'ll, '_>, ptr: &'ll Value, meta: &'ll Value) -> &'ll Value {
221 assert_eq!(abi::FAT_PTR_ADDR, 0);
222 assert_eq!(abi::FAT_PTR_EXTRA, 1);
223 C_struct(cx, &[ptr, meta], false)
226 pub fn C_struct(cx: &CodegenCx<'ll, '_>, elts: &[&'ll Value], packed: bool) -> &'ll Value {
227 C_struct_in_context(cx.llcx, elts, packed)
230 pub fn C_struct_in_context(
231 llcx: &'ll llvm::Context,
236 llvm::LLVMConstStructInContext(llcx,
237 elts.as_ptr(), elts.len() as c_uint,
242 pub fn C_array(ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value {
244 return llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint);
248 pub fn C_vector(elts: &[&'ll Value]) -> &'ll Value {
250 return llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint);
254 pub fn C_bytes(cx: &CodegenCx<'ll, '_>, bytes: &[u8]) -> &'ll Value {
255 C_bytes_in_context(cx.llcx, bytes)
258 pub fn C_bytes_in_context(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
260 let ptr = bytes.as_ptr() as *const c_char;
261 return llvm::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True);
265 pub fn const_get_elt(v: &'ll Value, idx: u64) -> &'ll Value {
267 assert_eq!(idx as c_uint as u64, idx);
268 let us = &[idx as c_uint];
269 let r = llvm::LLVMConstExtractValue(v, us.as_ptr(), us.len() as c_uint);
271 debug!("const_get_elt(v={:?}, idx={}, r={:?})",
278 pub fn const_get_real(v: &'ll Value) -> Option<(f64, bool)> {
280 if is_const_real(v) {
281 let mut loses_info: llvm::Bool = ::std::mem::uninitialized();
282 let r = llvm::LLVMConstRealGetDouble(v, &mut loses_info);
283 let loses_info = if loses_info == 1 { true } else { false };
284 Some((r, loses_info))
291 pub fn const_to_uint(v: &'ll Value) -> u64 {
293 llvm::LLVMConstIntGetZExtValue(v)
297 pub fn is_const_integral(v: &'ll Value) -> bool {
299 llvm::LLVMIsAConstantInt(v).is_some()
303 pub fn is_const_real(v: &'ll Value) -> bool {
305 llvm::LLVMIsAConstantFP(v).is_some()
311 fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
312 ((hi as u128) << 64) | (lo as u128)
315 pub fn const_to_opt_u128(v: &'ll Value, sign_ext: bool) -> Option<u128> {
317 if is_const_integral(v) {
318 let (mut lo, mut hi) = (0u64, 0u64);
319 let success = llvm::LLVMRustConstInt128Get(v, sign_ext,
322 Some(hi_lo_to_u128(lo, hi))
332 pub fn langcall(tcx: TyCtxt,
337 tcx.lang_items().require(li).unwrap_or_else(|s| {
338 let msg = format!("{} {}", msg, s);
340 Some(span) => tcx.sess.span_fatal(span, &msg[..]),
341 None => tcx.sess.fatal(&msg[..]),
346 // To avoid UB from LLVM, these two functions mask RHS with an
347 // appropriate mask unconditionally (i.e. the fallback behavior for
348 // all shifts). For 32- and 64-bit types, this matches the semantics
349 // of Java. (See related discussion on #1877 and #10183.)
351 pub fn build_unchecked_lshift(
352 bx: &Builder<'a, 'll, 'tcx>,
356 let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shl, lhs, rhs);
357 // #1877, #10183: Ensure that input is always valid
358 let rhs = shift_mask_rhs(bx, rhs);
362 pub fn build_unchecked_rshift(
363 bx: &Builder<'a, 'll, 'tcx>, lhs_t: Ty<'tcx>, lhs: &'ll Value, rhs: &'ll Value
365 let rhs = base::cast_shift_expr_rhs(bx, hir::BinOpKind::Shr, lhs, rhs);
366 // #1877, #10183: Ensure that input is always valid
367 let rhs = shift_mask_rhs(bx, rhs);
368 let is_signed = lhs_t.is_signed();
376 fn shift_mask_rhs(bx: &Builder<'a, 'll, 'tcx>, rhs: &'ll Value) -> &'ll Value {
377 let rhs_llty = val_ty(rhs);
378 bx.and(rhs, shift_mask_val(bx, rhs_llty, rhs_llty, false))
381 pub fn shift_mask_val(
382 bx: &Builder<'a, 'll, 'tcx>,
384 mask_llty: &'ll Type,
387 let kind = llty.kind();
389 TypeKind::Integer => {
390 // i8/u8 can shift by at most 7, i16/u16 by at most 15, etc.
391 let val = llty.int_width() - 1;
393 C_int(mask_llty, !val as i64)
395 C_uint(mask_llty, val)
398 TypeKind::Vector => {
399 let mask = shift_mask_val(bx, llty.element_type(), mask_llty.element_type(), invert);
400 bx.vector_splat(mask_llty.vector_length(), mask)
402 _ => bug!("shift_mask_val: expected Integer or Vector, found {:?}", kind),