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Diffstat (limited to 'compiler/rustc_codegen_llvm/src/common.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/common.rs | 359 |
1 files changed, 359 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 000000000..fb4da9a5f --- /dev/null +++ b/compiler/rustc_codegen_llvm/src/common.rs @@ -0,0 +1,359 @@ +//! Code that is useful in various codegen modules. + +use crate::consts::{self, 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::type_of::LayoutLlvmExt; +use crate::value::Value; + +use rustc_ast::Mutability; +use rustc_codegen_ssa::mir::place::PlaceRef; +use rustc_codegen_ssa::traits::*; +use rustc_middle::bug; +use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar}; +use rustc_middle::ty::layout::{LayoutOf, TyAndLayout}; +use rustc_target::abi::{self, AddressSpace, HasDataLayout, Pointer, Size}; + +use libc::{c_char, c_uint}; +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 { + unsafe { llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint) } + } + + pub fn const_vector(&self, elts: &[&'ll Value]) -> &'ll Value { + unsafe { llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint) } + } + + 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 { + assert_eq!(idx as c_uint as u64, idx); + let r = llvm::LLVMGetAggregateElement(v, idx as c_uint).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_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_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_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::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage); + } + (s.to_owned(), g) + }) + .1; + let len = s.len(); + let cs = consts::ptrcast( + str_global, + self.type_ptr_to(self.layout_of(self.tcx.types.str_).llvm_type(self)), + ); + (cs, 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).map(|v| unsafe { llvm::LLVMConstIntGetZExtValue(v) }) + } + + 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 zst_to_backend(&self, _llty: &'ll Type) -> &'ll Value { + self.const_undef(self.type_ix(0)) + } + + 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.assert_bits(layout.size(self)); + let llval = self.const_uint_big(self.type_ix(bitsize), data); + if layout.primitive() == Pointer { + unsafe { llvm::LLVMConstIntToPtr(llval, llty) } + } else { + self.const_bitcast(llval, llty) + } + } + Scalar::Ptr(ptr, _size) => { + let (alloc_id, offset) = ptr.into_parts(); + let (base_addr, base_addr_space) = match self.tcx.global_alloc(alloc_id) { + GlobalAlloc::Memory(alloc) => { + let init = const_alloc_to_llvm(self, alloc); + 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::set_value_name(value, format!("{:?}", alloc_id).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); + 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::LLVMRustConstInBoundsGEP2( + self.type_i8(), + self.const_bitcast(base_addr, self.type_i8p_ext(base_addr_space)), + &self.const_usize(offset.bytes()), + 1, + ) + }; + if 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) + } + + fn from_const_alloc( + &self, + layout: TyAndLayout<'tcx>, + alloc: ConstAllocation<'tcx>, + offset: Size, + ) -> PlaceRef<'tcx, &'ll Value> { + let alloc_align = alloc.inner().align; + assert_eq!(alloc_align, layout.align.abi); + let llty = self.type_ptr_to(layout.llvm_type(self)); + let llval = if layout.size == Size::ZERO { + let llval = self.const_usize(alloc_align.bytes()); + unsafe { llvm::LLVMConstIntToPtr(llval, llty) } + } else { + let init = const_alloc_to_llvm(self, alloc); + let base_addr = self.static_addr_of(init, alloc_align, None); + + let llval = unsafe { + llvm::LLVMRustConstInBoundsGEP2( + self.type_i8(), + self.const_bitcast(base_addr, self.type_i8p()), + &self.const_usize(offset.bytes()), + 1, + ) + }; + self.const_bitcast(llval, llty) + }; + PlaceRef::new_sized(llval, layout) + } + + fn const_ptrcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value { + consts::ptrcast(val, ty) + } +} + +/// 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::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True) + } +} + +pub fn struct_in_context<'ll>( + llcx: &'ll llvm::Context, + elts: &[&'ll Value], + packed: bool, +) -> &'ll Value { + unsafe { + llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), elts.len() as c_uint, 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) } +} |