From ac43d58d3aca4b578864ec6dbb24d68a9f9c201c Mon Sep 17 00:00:00 2001
From: Florian Zeitz <florob@babelmonkeys.de>
Date: Wed, 26 Jul 2017 16:27:25 +0200
Subject: trans: Optimize initialization using repeat expressions

This elides initialization for zero-sized arrays:
* for zero-sized elements we previously emitted an empty loop
* for arrays with a length of zero we previously emitted a loop with zero
  iterations

This emits llvm.memset() instead of a loop over each element when:
* all elements are zero integers
* elements are byte sized
---
 src/test/codegen/slice-init.rs | 74 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 src/test/codegen/slice-init.rs

(limited to 'src/test/codegen')

diff --git a/src/test/codegen/slice-init.rs b/src/test/codegen/slice-init.rs
new file mode 100644
index 00000000000..cb684af3953
--- /dev/null
+++ b/src/test/codegen/slice-init.rs
@@ -0,0 +1,74 @@
+// 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.
+
+// compile-flags: -C no-prepopulate-passes
+
+#![crate_type = "lib"]
+
+// CHECK-LABEL: @zero_sized_elem
+#[no_mangle]
+pub fn zero_sized_elem() {
+    // CHECK-NOT: br label %slice_loop_header{{.*}}
+    // CHECK-NOT: call void @llvm.memset.p0i8
+    let x = [(); 4];
+    drop(&x);
+}
+
+// CHECK-LABEL: @zero_len_array
+#[no_mangle]
+pub fn zero_len_array() {
+    // CHECK-NOT: br label %slice_loop_header{{.*}}
+    // CHECK-NOT: call void @llvm.memset.p0i8
+    let x = [4; 0];
+    drop(&x);
+}
+
+// CHECK-LABEL: @byte_array
+#[no_mangle]
+pub fn byte_array() {
+    // CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{.*}}, i8 7, i64 4
+    // CHECK-NOT: br label %slice_loop_header{{.*}}
+    let x = [7u8; 4];
+    drop(&x);
+}
+
+#[allow(dead_code)]
+#[derive(Copy, Clone)]
+enum Init {
+    Loop,
+    Memset,
+}
+
+// CHECK-LABEL: @byte_enum_array
+#[no_mangle]
+pub fn byte_enum_array() {
+    // CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{.*}}, i8 {{.*}}, i64 4
+    // CHECK-NOT: br label %slice_loop_header{{.*}}
+    let x = [Init::Memset; 4];
+    drop(&x);
+}
+
+// CHECK-LABEL: @zeroed_integer_array
+#[no_mangle]
+pub fn zeroed_integer_array() {
+    // CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{.*}}, i8 0, i64 16
+    // CHECK-NOT: br label %slice_loop_header{{.*}}
+    let x = [0u32; 4];
+    drop(&x);
+}
+
+// CHECK-LABEL: @nonzero_integer_array
+#[no_mangle]
+pub fn nonzero_integer_array() {
+    // CHECK: br label %slice_loop_header{{.*}}
+    // CHECK-NOT: call void @llvm.memset.p0i8
+    let x = [0x1a_2b_3c_4d_u32; 4];
+    drop(&x);
+}
-- 
cgit 1.4.1-3-g733a5


From 11d6312abd614fca3970902f137225e0437d0a09 Mon Sep 17 00:00:00 2001
From: Florian Zeitz <florob@babelmonkeys.de>
Date: Fri, 4 Aug 2017 16:58:12 +0200
Subject: codegen tests: Check type of `len` argument to `llvm.memset.*` based
 on the exact intrinsic used

---
 src/test/codegen/slice-init.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'src/test/codegen')

diff --git a/src/test/codegen/slice-init.rs b/src/test/codegen/slice-init.rs
index cb684af3953..569d937c812 100644
--- a/src/test/codegen/slice-init.rs
+++ b/src/test/codegen/slice-init.rs
@@ -33,7 +33,7 @@ pub fn zero_len_array() {
 // CHECK-LABEL: @byte_array
 #[no_mangle]
 pub fn byte_array() {
-    // CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{.*}}, i8 7, i64 4
+    // CHECK: call void @llvm.memset.p0i8.i[[WIDTH:[0-9]+]](i8* {{.*}}, i8 7, i[[WIDTH]] 4
     // CHECK-NOT: br label %slice_loop_header{{.*}}
     let x = [7u8; 4];
     drop(&x);
@@ -49,7 +49,7 @@ enum Init {
 // CHECK-LABEL: @byte_enum_array
 #[no_mangle]
 pub fn byte_enum_array() {
-    // CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{.*}}, i8 {{.*}}, i64 4
+    // CHECK: call void @llvm.memset.p0i8.i[[WIDTH:[0-9]+]](i8* {{.*}}, i8 {{.*}}, i[[WIDTH]] 4
     // CHECK-NOT: br label %slice_loop_header{{.*}}
     let x = [Init::Memset; 4];
     drop(&x);
@@ -58,7 +58,7 @@ pub fn byte_enum_array() {
 // CHECK-LABEL: @zeroed_integer_array
 #[no_mangle]
 pub fn zeroed_integer_array() {
-    // CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{.*}}, i8 0, i64 16
+    // CHECK: call void @llvm.memset.p0i8.i[[WIDTH:[0-9]+]](i8* {{.*}}, i8 0, i[[WIDTH]] 16
     // CHECK-NOT: br label %slice_loop_header{{.*}}
     let x = [0u32; 4];
     drop(&x);
-- 
cgit 1.4.1-3-g733a5