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//! Allocator shim
// Adapted from rustc
use crate::prelude::*;
use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
use rustc_session::config::OomStrategy;
use rustc_span::symbol::sym;
/// Returns whether an allocator shim was created
pub(crate) fn codegen(
tcx: TyCtxt<'_>,
module: &mut impl Module,
unwind_context: &mut UnwindContext,
) -> bool {
let any_dynamic_crate = tcx.dependency_formats(()).iter().any(|(_, list)| {
use rustc_middle::middle::dependency_format::Linkage;
list.iter().any(|&linkage| linkage == Linkage::Dynamic)
});
if any_dynamic_crate {
false
} else if let Some(kind) = tcx.allocator_kind(()) {
codegen_inner(
module,
unwind_context,
kind,
tcx.alloc_error_handler_kind(()).unwrap(),
tcx.sess.opts.unstable_opts.oom,
);
true
} else {
false
}
}
fn codegen_inner(
module: &mut impl Module,
unwind_context: &mut UnwindContext,
kind: AllocatorKind,
alloc_error_handler_kind: AllocatorKind,
oom_strategy: OomStrategy,
) {
let usize_ty = module.target_config().pointer_type();
for method in ALLOCATOR_METHODS {
let mut arg_tys = Vec::with_capacity(method.inputs.len());
for ty in method.inputs.iter() {
match *ty {
AllocatorTy::Layout => {
arg_tys.push(usize_ty); // size
arg_tys.push(usize_ty); // align
}
AllocatorTy::Ptr => arg_tys.push(usize_ty),
AllocatorTy::Usize => arg_tys.push(usize_ty),
AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
}
}
let output = match method.output {
AllocatorTy::ResultPtr => Some(usize_ty),
AllocatorTy::Unit => None,
AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
panic!("invalid allocator output")
}
};
let sig = Signature {
call_conv: module.target_config().default_call_conv,
params: arg_tys.iter().cloned().map(AbiParam::new).collect(),
returns: output.into_iter().map(AbiParam::new).collect(),
};
let caller_name = format!("__rust_{}", method.name);
let callee_name = kind.fn_name(method.name);
let func_id = module.declare_function(&caller_name, Linkage::Export, &sig).unwrap();
let callee_func_id = module.declare_function(&callee_name, Linkage::Import, &sig).unwrap();
let mut ctx = Context::new();
ctx.func.signature = sig.clone();
{
let mut func_ctx = FunctionBuilderContext::new();
let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
let args = arg_tys
.into_iter()
.map(|ty| bcx.append_block_param(block, ty))
.collect::<Vec<Value>>();
let callee_func_ref = module.declare_func_in_func(callee_func_id, &mut bcx.func);
let call_inst = bcx.ins().call(callee_func_ref, &args);
let results = bcx.inst_results(call_inst).to_vec(); // Clone to prevent borrow error
bcx.ins().return_(&results);
bcx.seal_all_blocks();
bcx.finalize();
}
module.define_function(func_id, &mut ctx).unwrap();
unwind_context.add_function(func_id, &ctx, module.isa());
}
let sig = Signature {
call_conv: module.target_config().default_call_conv,
params: vec![AbiParam::new(usize_ty), AbiParam::new(usize_ty)],
returns: vec![],
};
let callee_name = alloc_error_handler_kind.fn_name(sym::oom);
let func_id =
module.declare_function("__rust_alloc_error_handler", Linkage::Export, &sig).unwrap();
let callee_func_id = module.declare_function(&callee_name, Linkage::Import, &sig).unwrap();
let mut ctx = Context::new();
ctx.func.signature = sig;
{
let mut func_ctx = FunctionBuilderContext::new();
let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
let block = bcx.create_block();
bcx.switch_to_block(block);
let args = (&[usize_ty, usize_ty])
.iter()
.map(|&ty| bcx.append_block_param(block, ty))
.collect::<Vec<Value>>();
let callee_func_ref = module.declare_func_in_func(callee_func_id, &mut bcx.func);
bcx.ins().call(callee_func_ref, &args);
bcx.ins().trap(TrapCode::UnreachableCodeReached);
bcx.seal_all_blocks();
bcx.finalize();
}
module.define_function(func_id, &mut ctx).unwrap();
unwind_context.add_function(func_id, &ctx, module.isa());
let data_id = module.declare_data(OomStrategy::SYMBOL, Linkage::Export, false, false).unwrap();
let mut data_ctx = DataContext::new();
data_ctx.set_align(1);
let val = oom_strategy.should_panic();
data_ctx.define(Box::new([val]));
module.define_data(data_id, &data_ctx).unwrap();
}
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