From 733cb54d18c6c3bbd8dfcd6184cdf678bd64bd0e Mon Sep 17 00:00:00 2001
From: bors <bors@rust-lang.org>
Date: Sat, 26 Dec 2020 06:43:51 +0000
Subject: Remove pointer comparison from slice equality

This resurrects #71735.

Fixes #71602, helps with #80140.

r? `@Mark-Simulacrum`
---
 src/test/codegen/slice-ref-equality.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 src/test/codegen/slice-ref-equality.rs

(limited to 'src/test/codegen')

diff --git a/src/test/codegen/slice-ref-equality.rs b/src/test/codegen/slice-ref-equality.rs
new file mode 100644
index 00000000000..acc7879e7b1
--- /dev/null
+++ b/src/test/codegen/slice-ref-equality.rs
@@ -0,0 +1,16 @@
+// compile-flags: -C opt-level=3
+
+#![crate_type = "lib"]
+
+// #71602: check that slice equality just generates a single bcmp
+
+// CHECK-LABEL: @is_zero_slice
+#[no_mangle]
+pub fn is_zero_slice(data: &[u8; 4]) -> bool {
+    // CHECK: start:
+    // CHECK-NEXT: %{{.+}} = getelementptr {{.+}}
+    // CHECK-NEXT: %[[BCMP:.+]] = tail call i32 @{{bcmp|memcmp}}({{.+}})
+    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[BCMP]], 0
+    // CHECK-NEXT: ret i1 %[[EQ]]
+    *data == [0; 4]
+}
-- 
cgit 1.4.1-3-g733a5