rust/src/librustc_codegen_llvm/mir/constant.rs
2018-05-24 20:49:37 +02:00

228 lines
8.7 KiB
Rust

// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use llvm::{self, ValueRef};
use rustc::middle::const_val::{ConstVal, ConstEvalErr};
use rustc_mir::interpret::{read_target_uint, const_val_field};
use rustc::hir::def_id::DefId;
use rustc::mir;
use rustc_data_structures::indexed_vec::Idx;
use rustc::mir::interpret::{GlobalId, Pointer, Scalar, Allocation, ConstValue, AllocType};
use rustc::ty::{self, Ty};
use rustc::ty::layout::{self, HasDataLayout, LayoutOf, Size};
use builder::Builder;
use common::{CodegenCx};
use common::{C_bytes, C_struct, C_uint_big, C_undef, C_usize};
use consts;
use type_of::LayoutLlvmExt;
use type_::Type;
use syntax::ast::Mutability;
use super::super::callee;
use super::FunctionCx;
pub fn primval_to_llvm(cx: &CodegenCx,
cv: Scalar,
layout: &layout::Scalar,
llty: Type) -> ValueRef {
let bitsize = if layout.is_bool() { 1 } else { layout.value.size(cx).bits() };
match cv {
Scalar::Bits { defined, .. } if (defined as u64) < bitsize || defined == 0 => {
C_undef(Type::ix(cx, bitsize))
},
Scalar::Bits { bits, .. } => {
let llval = C_uint_big(Type::ix(cx, bitsize), bits);
if layout.value == layout::Pointer {
unsafe { llvm::LLVMConstIntToPtr(llval, llty.to_ref()) }
} else {
consts::bitcast(llval, llty)
}
},
Scalar::Ptr(ptr) => {
let alloc_type = cx.tcx.alloc_map.lock().get(ptr.alloc_id);
let base_addr = match alloc_type {
Some(AllocType::Memory(alloc)) => {
let init = const_alloc_to_llvm(cx, alloc);
if alloc.runtime_mutability == Mutability::Mutable {
consts::addr_of_mut(cx, init, alloc.align, "byte_str")
} else {
consts::addr_of(cx, init, alloc.align, "byte_str")
}
}
Some(AllocType::Function(fn_instance)) => {
callee::get_fn(cx, fn_instance)
}
Some(AllocType::Static(def_id)) => {
assert!(cx.tcx.is_static(def_id).is_some());
consts::get_static(cx, def_id)
}
None => bug!("missing allocation {:?}", ptr.alloc_id),
};
let llval = unsafe { llvm::LLVMConstInBoundsGEP(
consts::bitcast(base_addr, Type::i8p(cx)),
&C_usize(cx, ptr.offset.bytes()),
1,
) };
if layout.value != layout::Pointer {
unsafe { llvm::LLVMConstPtrToInt(llval, llty.to_ref()) }
} else {
consts::bitcast(llval, llty)
}
}
}
}
pub fn const_alloc_to_llvm(cx: &CodegenCx, alloc: &Allocation) -> ValueRef {
let mut llvals = Vec::with_capacity(alloc.relocations.len() + 1);
let layout = cx.data_layout();
let pointer_size = layout.pointer_size.bytes() as usize;
let mut next_offset = 0;
for &(offset, alloc_id) in alloc.relocations.iter() {
let offset = offset.bytes();
assert_eq!(offset as usize as u64, offset);
let offset = offset as usize;
if offset > next_offset {
llvals.push(C_bytes(cx, &alloc.bytes[next_offset..offset]));
}
let ptr_offset = read_target_uint(
layout.endian,
&alloc.bytes[offset..(offset + pointer_size)],
).expect("const_alloc_to_llvm: could not read relocation pointer") as u64;
llvals.push(primval_to_llvm(
cx,
Pointer { alloc_id, offset: Size::from_bytes(ptr_offset) }.into(),
&layout::Scalar {
value: layout::Primitive::Pointer,
valid_range: 0..=!0
},
Type::i8p(cx)
));
next_offset = offset + pointer_size;
}
if alloc.bytes.len() >= next_offset {
llvals.push(C_bytes(cx, &alloc.bytes[next_offset ..]));
}
C_struct(cx, &llvals, true)
}
pub fn codegen_static_initializer<'a, 'tcx>(
cx: &CodegenCx<'a, 'tcx>,
def_id: DefId)
-> Result<ValueRef, ConstEvalErr<'tcx>>
{
let instance = ty::Instance::mono(cx.tcx, def_id);
let cid = GlobalId {
instance,
promoted: None
};
let param_env = ty::ParamEnv::reveal_all();
let static_ = cx.tcx.const_eval(param_env.and(cid))?;
let alloc = match static_.val {
ConstVal::Value(ConstValue::ByRef(alloc, n)) if n.bytes() == 0 => alloc,
_ => bug!("static const eval returned {:#?}", static_),
};
Ok(const_alloc_to_llvm(cx, alloc))
}
impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
fn const_to_const_value(
&mut self,
bx: &Builder<'a, 'tcx>,
constant: &'tcx ty::Const<'tcx>,
) -> Result<ConstValue<'tcx>, ConstEvalErr<'tcx>> {
match constant.val {
ConstVal::Unevaluated(def_id, ref substs) => {
let tcx = bx.tcx();
let param_env = ty::ParamEnv::reveal_all();
let instance = ty::Instance::resolve(tcx, param_env, def_id, substs).unwrap();
let cid = GlobalId {
instance,
promoted: None,
};
let c = tcx.const_eval(param_env.and(cid))?;
self.const_to_const_value(bx, c)
},
ConstVal::Value(val) => Ok(val),
}
}
pub fn mir_constant_to_const_value(
&mut self,
bx: &Builder<'a, 'tcx>,
constant: &mir::Constant<'tcx>,
) -> Result<ConstValue<'tcx>, ConstEvalErr<'tcx>> {
match constant.literal {
mir::Literal::Promoted { index } => {
let param_env = ty::ParamEnv::reveal_all();
let cid = mir::interpret::GlobalId {
instance: self.instance,
promoted: Some(index),
};
bx.tcx().const_eval(param_env.and(cid))
}
mir::Literal::Value { value } => {
Ok(self.monomorphize(&value))
}
}.and_then(|c| self.const_to_const_value(bx, c))
}
/// process constant containing SIMD shuffle indices
pub fn simd_shuffle_indices(
&mut self,
bx: &Builder<'a, 'tcx>,
constant: &mir::Constant<'tcx>,
) -> (ValueRef, Ty<'tcx>) {
self.mir_constant_to_const_value(bx, constant)
.and_then(|c| {
let field_ty = constant.ty.builtin_index().unwrap();
let fields = match constant.ty.sty {
ty::TyArray(_, n) => n.unwrap_usize(bx.tcx()),
ref other => bug!("invalid simd shuffle type: {}", other),
};
let values: Result<Vec<ValueRef>, _> = (0..fields).map(|field| {
let field = const_val_field(
bx.tcx(),
ty::ParamEnv::reveal_all(),
self.instance,
None,
mir::Field::new(field as usize),
c,
constant.ty,
)?;
if let Some(prim) = field.to_primval() {
let layout = bx.cx.layout_of(field_ty);
let scalar = match layout.abi {
layout::Abi::Scalar(ref x) => x,
_ => bug!("from_const: invalid ByVal layout: {:#?}", layout)
};
Ok(primval_to_llvm(
bx.cx, prim, scalar,
layout.immediate_llvm_type(bx.cx),
))
} else {
bug!("simd shuffle field {:?}", field)
}
}).collect();
let llval = C_struct(bx.cx, &values?, false);
Ok((llval, constant.ty))
})
.unwrap_or_else(|e| {
e.report(bx.tcx(), constant.span, "shuffle_indices");
// We've errored, so we don't have to produce working code.
let ty = self.monomorphize(&constant.ty);
let llty = bx.cx.layout_of(ty).llvm_type(bx.cx);
(C_undef(llty), ty)
})
}
}