0473a4f1d8
Initially MIR differentiated between arguments and locals, which introduced a need to add extra copies assigning the argument to a local, even for simple bindings. This differentiation no longer exists, but we're still creating those copies, bloating the MIR and LLVM IR we emit. Additionally, the current approach means that we create debug info for both the incoming argument (marking it as an argument), and then immediately shadow it a local that goes by the same name. This can be confusing when using e.g. "info args" in gdb, or when e.g. a debugger with a GUI displays the function arguments separately from the local variables, especially when the binding is mutable, because the argument doesn't change, while the local variable does.
30 lines
909 B
Rust
30 lines
909 B
Rust
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// compile-flags: -C no-prepopulate-passes
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#![feature(core_intrinsics)]
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#![crate_type = "lib"]
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// test that `move_val_init` actually avoids big allocas
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use std::intrinsics::move_val_init;
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pub struct Big {
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pub data: [u8; 65536]
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}
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// CHECK-LABEL: @test_mvi
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#[no_mangle]
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pub unsafe fn test_mvi(target: *mut Big, make_big: fn() -> Big) {
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// CHECK: call void %make_big(%Big*{{[^%]*}} %target)
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move_val_init(target, make_big());
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}
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