[PATCH 20/22] aarch64: Add tests and docs for indirect_return attribute

[Yury Khrustalev]

From: Richard Ball <richard.b...@arm.com>

This patch adds a new testcase and docs
for the indirect_return attribute.

gcc/ChangeLog:

        * doc/extend.texi: Add AArch64 docs for indirect_return
        attribute.

gcc/testsuite/ChangeLog:

        * gcc.target/aarch64/indirect_return.c: New test.
        Co-authored-by: Yury Khrustalev <yury.khrusta...@arm.com>
---
 gcc/doc/extend.texi                           |  5 ++++
 .../gcc.target/aarch64/indirect_return.c      | 25 +++++++++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/indirect_return.c

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 42bd567119d..45e2b3ec569 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -4760,6 +4760,11 @@ Enable or disable calls to out-of-line helpers to 
implement atomic operations.
 This corresponds to the behavior of the command-line options
 @option{-moutline-atomics} and @option{-mno-outline-atomics}.
 
+@cindex @code{indirect_return} function attribute, AArch64
+@item indirect_return
+Used to inform the compiler that a function may return via
+an indirect return. Adds a BTI J instruction under 
@option{mbranch-protection=} bti.
+
 @end table
 
 The above target attributes can be specified as follows:
diff --git a/gcc/testsuite/gcc.target/aarch64/indirect_return.c 
b/gcc/testsuite/gcc.target/aarch64/indirect_return.c
new file mode 100644
index 00000000000..f1ef56d5557
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/indirect_return.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-mbranch-protection=bti" } */
+
+int __attribute((indirect_return))
+foo (int a)
+{
+  return a;
+}
+
+/*
+**func1:
+**     hint    34 // bti c
+**     ...
+**     bl      foo
+**     hint    36 // bti j
+**     ...
+**     ret
+*/
+int
+func1 (int a, int b)
+{
+  return foo (a + b);
+}
+
+/* { dg-final { check-function-bodies "**" "" "" } } */
-- 
2.39.5