Allocator shim

1 files changed, 81 insertions, 0 deletions

diff --git a/src/allocator.rs b/src/allocator.rs
new file mode 100644
index 00000000000..72ddf5312bd
--- /dev/null
+++ b/src/allocator.rs
@@ -0,0 +1,81 @@
+// Copyright 2017 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 crate::prelude::*;
+
+use crate::rustc::middle::allocator::AllocatorKind;
+use crate::rustc_allocator::{ALLOCATOR_METHODS, AllocatorTy};
+
+pub fn codegen(tcx: TyCtxt, module: &mut Module<impl Backend + 'static>, kind: AllocatorKind) {
+    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: CallConv::Fast,
+            params: arg_tys.iter().cloned().map(AbiParam::new).collect(),
+            returns: output.into_iter().map(AbiParam::new).collect(),
+        };
+
+        let func_id = module
+            .declare_function(&format!("__rust_{}", method.name), Linkage::Export, &sig)
+            .unwrap();
+
+        let callee_func_id = module
+            .declare_function(&kind.fn_name(method.name), Linkage::Import, &sig)
+            .unwrap();
+
+        let mut ctx = Context::new();
+        ctx.func = Function::with_name_signature(ExternalName::user(0, 0), sig.clone());
+        {
+            let mut func_ctx = FunctionBuilderContext::new();
+            let mut bcx: FunctionBuilder = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
+
+            let ebb = bcx.create_ebb();
+            bcx.switch_to_block(ebb);
+            let args = arg_tys
+                .into_iter()
+                .map(|ty| bcx.append_ebb_param(ebb, 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();
+    }
+}