diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/common.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/common.rs | 446 |
1 files changed, 446 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs new file mode 100644 index 00000000000..4ffc92eb633 --- /dev/null +++ b/compiler/rustc_codegen_llvm/src/common.rs @@ -0,0 +1,446 @@ +//! Code that is useful in various codegen modules. + +use crate::consts::const_alloc_to_llvm; +pub use crate::context::CodegenCx; +use crate::llvm::{self, BasicBlock, Bool, ConstantInt, False, OperandBundleDef, True}; +use crate::type_::Type; +use crate::value::Value; + +use rustc_ast::Mutability; +use rustc_codegen_ssa::traits::*; +use rustc_data_structures::stable_hasher::{Hash128, HashStable, StableHasher}; +use rustc_hir::def_id::DefId; +use rustc_middle::bug; +use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar}; +use rustc_middle::ty::TyCtxt; +use rustc_session::cstore::{DllCallingConvention, DllImport, PeImportNameType}; +use rustc_target::abi::{self, AddressSpace, HasDataLayout, Pointer}; +use rustc_target::spec::Target; + +use libc::{c_char, c_uint}; +use std::fmt::Write; +use tracing::debug; + +/* +* A note on nomenclature of linking: "extern", "foreign", and "upcall". +* +* An "extern" is an LLVM symbol we wind up emitting an undefined external +* reference to. This means "we don't have the thing in this compilation unit, +* please make sure you link it in at runtime". This could be a reference to +* C code found in a C library, or rust code found in a rust crate. +* +* Most "externs" are implicitly declared (automatically) as a result of a +* user declaring an extern _module_ dependency; this causes the rust driver +* to locate an extern crate, scan its compilation metadata, and emit extern +* declarations for any symbols used by the declaring crate. +* +* A "foreign" is an extern that references C (or other non-rust ABI) code. +* There is no metadata to scan for extern references so in these cases either +* a header-digester like bindgen, or manual function prototypes, have to +* serve as declarators. So these are usually given explicitly as prototype +* declarations, in rust code, with ABI attributes on them noting which ABI to +* link via. +* +* An "upcall" is a foreign call generated by the compiler (not corresponding +* to any user-written call in the code) into the runtime library, to perform +* some helper task such as bringing a task to life, allocating memory, etc. +* +*/ + +/// A structure representing an active landing pad for the duration of a basic +/// block. +/// +/// Each `Block` may contain an instance of this, indicating whether the block +/// is part of a landing pad or not. This is used to make decision about whether +/// to emit `invoke` instructions (e.g., in a landing pad we don't continue to +/// use `invoke`) and also about various function call metadata. +/// +/// For GNU exceptions (`landingpad` + `resume` instructions) this structure is +/// just a bunch of `None` instances (not too interesting), but for MSVC +/// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data. +/// When inside of a landing pad, each function call in LLVM IR needs to be +/// annotated with which landing pad it's a part of. This is accomplished via +/// the `OperandBundleDef` value created for MSVC landing pads. +pub struct Funclet<'ll> { + cleanuppad: &'ll Value, + operand: OperandBundleDef<'ll>, +} + +impl<'ll> Funclet<'ll> { + pub fn new(cleanuppad: &'ll Value) -> Self { + Funclet { cleanuppad, operand: OperandBundleDef::new("funclet", &[cleanuppad]) } + } + + pub fn cleanuppad(&self) -> &'ll Value { + self.cleanuppad + } + + pub fn bundle(&self) -> &OperandBundleDef<'ll> { + &self.operand + } +} + +impl<'ll> BackendTypes for CodegenCx<'ll, '_> { + type Value = &'ll Value; + // FIXME(eddyb) replace this with a `Function` "subclass" of `Value`. + type Function = &'ll Value; + + type BasicBlock = &'ll BasicBlock; + type Type = &'ll Type; + type Funclet = Funclet<'ll>; + + type DIScope = &'ll llvm::debuginfo::DIScope; + type DILocation = &'ll llvm::debuginfo::DILocation; + type DIVariable = &'ll llvm::debuginfo::DIVariable; +} + +impl<'ll> CodegenCx<'ll, '_> { + pub fn const_array(&self, ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value { + let len = u64::try_from(elts.len()).expect("LLVMConstArray2 elements len overflow"); + unsafe { llvm::LLVMConstArray2(ty, elts.as_ptr(), len) } + } + + pub fn const_vector(&self, elts: &[&'ll Value]) -> &'ll Value { + let len = c_uint::try_from(elts.len()).expect("LLVMConstVector elements len overflow"); + unsafe { llvm::LLVMConstVector(elts.as_ptr(), len) } + } + + pub fn const_bytes(&self, bytes: &[u8]) -> &'ll Value { + bytes_in_context(self.llcx, bytes) + } + + pub fn const_get_elt(&self, v: &'ll Value, idx: u64) -> &'ll Value { + unsafe { + let idx = c_uint::try_from(idx).expect("LLVMGetAggregateElement index overflow"); + let r = llvm::LLVMGetAggregateElement(v, idx).unwrap(); + + debug!("const_get_elt(v={:?}, idx={}, r={:?})", v, idx, r); + + r + } + } +} + +impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> { + fn const_null(&self, t: &'ll Type) -> &'ll Value { + unsafe { llvm::LLVMConstNull(t) } + } + + fn const_undef(&self, t: &'ll Type) -> &'ll Value { + unsafe { llvm::LLVMGetUndef(t) } + } + + fn const_poison(&self, t: &'ll Type) -> &'ll Value { + unsafe { llvm::LLVMGetPoison(t) } + } + + fn const_int(&self, t: &'ll Type, i: i64) -> &'ll Value { + unsafe { llvm::LLVMConstInt(t, i as u64, True) } + } + + fn const_uint(&self, t: &'ll Type, i: u64) -> &'ll Value { + unsafe { llvm::LLVMConstInt(t, i, False) } + } + + fn const_uint_big(&self, t: &'ll Type, u: u128) -> &'ll Value { + unsafe { + let words = [u as u64, (u >> 64) as u64]; + llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr()) + } + } + + fn const_bool(&self, val: bool) -> &'ll Value { + self.const_uint(self.type_i1(), val as u64) + } + + fn const_i16(&self, i: i16) -> &'ll Value { + self.const_int(self.type_i16(), i as i64) + } + + fn const_i32(&self, i: i32) -> &'ll Value { + self.const_int(self.type_i32(), i as i64) + } + + fn const_i8(&self, i: i8) -> &'ll Value { + self.const_int(self.type_i8(), i as i64) + } + + fn const_u32(&self, i: u32) -> &'ll Value { + self.const_uint(self.type_i32(), i as u64) + } + + fn const_u64(&self, i: u64) -> &'ll Value { + self.const_uint(self.type_i64(), i) + } + + fn const_u128(&self, i: u128) -> &'ll Value { + self.const_uint_big(self.type_i128(), i) + } + + fn const_usize(&self, i: u64) -> &'ll Value { + let bit_size = self.data_layout().pointer_size.bits(); + if bit_size < 64 { + // make sure it doesn't overflow + assert!(i < (1 << bit_size)); + } + + self.const_uint(self.isize_ty, i) + } + + fn const_u8(&self, i: u8) -> &'ll Value { + self.const_uint(self.type_i8(), i as u64) + } + + fn const_real(&self, t: &'ll Type, val: f64) -> &'ll Value { + unsafe { llvm::LLVMConstReal(t, val) } + } + + fn const_str(&self, s: &str) -> (&'ll Value, &'ll Value) { + let str_global = *self + .const_str_cache + .borrow_mut() + .raw_entry_mut() + .from_key(s) + .or_insert_with(|| { + let sc = self.const_bytes(s.as_bytes()); + let sym = self.generate_local_symbol_name("str"); + let g = self.define_global(&sym, self.val_ty(sc)).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", sym); + }); + unsafe { + llvm::LLVMSetInitializer(g, sc); + llvm::LLVMSetGlobalConstant(g, True); + llvm::LLVMSetUnnamedAddress(g, llvm::UnnamedAddr::Global); + llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage); + } + (s.to_owned(), g) + }) + .1; + let len = s.len(); + (str_global, self.const_usize(len as u64)) + } + + fn const_struct(&self, elts: &[&'ll Value], packed: bool) -> &'ll Value { + struct_in_context(self.llcx, elts, packed) + } + + fn const_to_opt_uint(&self, v: &'ll Value) -> Option<u64> { + try_as_const_integral(v).and_then(|v| unsafe { + let mut i = 0u64; + let success = llvm::LLVMRustConstIntGetZExtValue(v, &mut i); + success.then_some(i) + }) + } + + fn const_to_opt_u128(&self, v: &'ll Value, sign_ext: bool) -> Option<u128> { + try_as_const_integral(v).and_then(|v| unsafe { + let (mut lo, mut hi) = (0u64, 0u64); + let success = llvm::LLVMRustConstInt128Get(v, sign_ext, &mut hi, &mut lo); + success.then_some(hi_lo_to_u128(lo, hi)) + }) + } + + fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: &'ll Type) -> &'ll Value { + let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() }; + match cv { + Scalar::Int(int) => { + let data = int.to_bits(layout.size(self)); + let llval = self.const_uint_big(self.type_ix(bitsize), data); + if matches!(layout.primitive(), Pointer(_)) { + unsafe { llvm::LLVMConstIntToPtr(llval, llty) } + } else { + self.const_bitcast(llval, llty) + } + } + Scalar::Ptr(ptr, _size) => { + let (prov, offset) = ptr.into_parts(); + let (base_addr, base_addr_space) = match self.tcx.global_alloc(prov.alloc_id()) { + GlobalAlloc::Memory(alloc) => { + // For ZSTs directly codegen an aligned pointer. + // This avoids generating a zero-sized constant value and actually needing a + // real address at runtime. + if alloc.inner().len() == 0 { + assert_eq!(offset.bytes(), 0); + let llval = self.const_usize(alloc.inner().align.bytes()); + return if matches!(layout.primitive(), Pointer(_)) { + unsafe { llvm::LLVMConstIntToPtr(llval, llty) } + } else { + self.const_bitcast(llval, llty) + }; + } else { + let init = const_alloc_to_llvm(self, alloc, /*static*/ false); + let alloc = alloc.inner(); + let value = match alloc.mutability { + Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None), + _ => self.static_addr_of(init, alloc.align, None), + }; + if !self.sess().fewer_names() && llvm::get_value_name(value).is_empty() + { + let hash = self.tcx.with_stable_hashing_context(|mut hcx| { + let mut hasher = StableHasher::new(); + alloc.hash_stable(&mut hcx, &mut hasher); + hasher.finish::<Hash128>() + }); + llvm::set_value_name( + value, + format!("alloc_{hash:032x}").as_bytes(), + ); + } + (value, AddressSpace::DATA) + } + } + GlobalAlloc::Function(fn_instance) => ( + self.get_fn_addr(fn_instance.polymorphize(self.tcx)), + self.data_layout().instruction_address_space, + ), + GlobalAlloc::VTable(ty, trait_ref) => { + let alloc = self + .tcx + .global_alloc(self.tcx.vtable_allocation((ty, trait_ref))) + .unwrap_memory(); + let init = const_alloc_to_llvm(self, alloc, /*static*/ false); + let value = self.static_addr_of(init, alloc.inner().align, None); + (value, AddressSpace::DATA) + } + GlobalAlloc::Static(def_id) => { + assert!(self.tcx.is_static(def_id)); + assert!(!self.tcx.is_thread_local_static(def_id)); + (self.get_static(def_id), AddressSpace::DATA) + } + }; + let llval = unsafe { + llvm::LLVMConstInBoundsGEP2( + self.type_i8(), + self.const_bitcast(base_addr, self.type_ptr_ext(base_addr_space)), + &self.const_usize(offset.bytes()), + 1, + ) + }; + if !matches!(layout.primitive(), Pointer(_)) { + unsafe { llvm::LLVMConstPtrToInt(llval, llty) } + } else { + self.const_bitcast(llval, llty) + } + } + } + } + + fn const_data_from_alloc(&self, alloc: ConstAllocation<'tcx>) -> Self::Value { + const_alloc_to_llvm(self, alloc, /*static*/ false) + } + + fn const_bitcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value { + self.const_bitcast(val, ty) + } + + fn const_ptr_byte_offset(&self, base_addr: Self::Value, offset: abi::Size) -> Self::Value { + unsafe { + llvm::LLVMConstInBoundsGEP2( + self.type_i8(), + base_addr, + &self.const_usize(offset.bytes()), + 1, + ) + } + } +} + +/// Get the [LLVM type][Type] of a [`Value`]. +pub fn val_ty(v: &Value) -> &Type { + unsafe { llvm::LLVMTypeOf(v) } +} + +pub fn bytes_in_context<'ll>(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value { + unsafe { + let ptr = bytes.as_ptr() as *const c_char; + llvm::LLVMConstStringInContext2(llcx, ptr, bytes.len(), True) + } +} + +pub fn struct_in_context<'ll>( + llcx: &'ll llvm::Context, + elts: &[&'ll Value], + packed: bool, +) -> &'ll Value { + let len = c_uint::try_from(elts.len()).expect("LLVMConstStructInContext elements len overflow"); + unsafe { llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), len, packed as Bool) } +} + +#[inline] +fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 { + ((hi as u128) << 64) | (lo as u128) +} + +fn try_as_const_integral(v: &Value) -> Option<&ConstantInt> { + unsafe { llvm::LLVMIsAConstantInt(v) } +} + +pub(crate) fn get_dllimport<'tcx>( + tcx: TyCtxt<'tcx>, + id: DefId, + name: &str, +) -> Option<&'tcx DllImport> { + tcx.native_library(id) + .and_then(|lib| lib.dll_imports.iter().find(|di| di.name.as_str() == name)) +} + +pub(crate) fn is_mingw_gnu_toolchain(target: &Target) -> bool { + target.vendor == "pc" && target.os == "windows" && target.env == "gnu" && target.abi.is_empty() +} + +pub(crate) fn i686_decorated_name( + dll_import: &DllImport, + mingw: bool, + disable_name_mangling: bool, +) -> String { + let name = dll_import.name.as_str(); + + let (add_prefix, add_suffix) = match dll_import.import_name_type { + Some(PeImportNameType::NoPrefix) => (false, true), + Some(PeImportNameType::Undecorated) => (false, false), + _ => (true, true), + }; + + // Worst case: +1 for disable name mangling, +1 for prefix, +4 for suffix (@@__). + let mut decorated_name = String::with_capacity(name.len() + 6); + + if disable_name_mangling { + // LLVM uses a binary 1 ('\x01') prefix to a name to indicate that mangling needs to be disabled. + decorated_name.push('\x01'); + } + + let prefix = if add_prefix && dll_import.is_fn { + match dll_import.calling_convention { + DllCallingConvention::C | DllCallingConvention::Vectorcall(_) => None, + DllCallingConvention::Stdcall(_) => (!mingw + || dll_import.import_name_type == Some(PeImportNameType::Decorated)) + .then_some('_'), + DllCallingConvention::Fastcall(_) => Some('@'), + } + } else if !dll_import.is_fn && !mingw { + // For static variables, prefix with '_' on MSVC. + Some('_') + } else { + None + }; + if let Some(prefix) = prefix { + decorated_name.push(prefix); + } + + decorated_name.push_str(name); + + if add_suffix && dll_import.is_fn { + match dll_import.calling_convention { + DllCallingConvention::C => {} + DllCallingConvention::Stdcall(arg_list_size) + | DllCallingConvention::Fastcall(arg_list_size) => { + write!(&mut decorated_name, "@{arg_list_size}").unwrap(); + } + DllCallingConvention::Vectorcall(arg_list_size) => { + write!(&mut decorated_name, "@@{arg_list_size}").unwrap(); + } + } + } + + decorated_name +} |