From 6def06c973b3aded197789c4b02d20ad378165f8 Mon Sep 17 00:00:00 2001 From: Björn Steinbrink Date: Wed, 16 Sep 2015 01:26:58 +0200 Subject: Don't create adjustments from a type to itself Currently, we're generating adjustments, for example, to get from &[u8] to &[u8], which is unneeded and kicks us out of trans_into() into trans() which means an additional stack slot and copy in the unoptimized code. --- src/test/codegen/adjustments.rs | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 src/test/codegen/adjustments.rs (limited to 'src/test/codegen') diff --git a/src/test/codegen/adjustments.rs b/src/test/codegen/adjustments.rs new file mode 100644 index 00000000000..b0438f561b9 --- /dev/null +++ b/src/test/codegen/adjustments.rs @@ -0,0 +1,28 @@ +// Copyright 2015 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// compile-flags: -C no-prepopulate-passes + +// Hack to get the correct size for the length part in slices +// CHECK: @helper([[USIZE:i[0-9]+]]) +#[no_mangle] +fn helper(_: usize) { +} + +// CHECK-LABEL: @no_op_slice_adjustment +#[no_mangle] +pub fn no_op_slice_adjustment(x: &[u8]) -> &[u8] { + // We used to generate an extra alloca and memcpy for the block's trailing expression value, so + // check that we copy directly to the return value slot +// CHECK: [[SRC:%[0-9]+]] = bitcast { i8*, [[USIZE]] }* %x to +// CHECK: [[DST:%[0-9]+]] = bitcast { i8*, [[USIZE]] }* %sret_slot to i8* +// CHECK: call void @llvm.memcpy.{{.*}}(i8* [[DST]], i8* [[SRC]], + { x } +} -- cgit 1.4.1-3-g733a5