On Wed, Jul 18, 2018 at 5:33 PM H.J. Lu <hongjiu...@intel.com> wrote:
>
> In
>
> struct ucontext;
> typedef struct ucontext ucontext_t;
>
> extern int (*bar) (ucontext_t *__restrict __oucp,
> const ucontext_t *__restrict __ucp)
> __attribute__((__indirect_return__));
>
> extern int res;
>
> void
> foo (ucontext_t *oucp, ucontext_t *ucp)
> {
> res = bar (oucp, ucp);
> }
>
> bar() may return via indirect branch. This patch changes indirect_return
> to type attribute to allow indirect_return attribute on variable or type
> of function pointer so that ENDBR can be inserted after call to bar().
>
> Tested on i386 and x86-64. OK for trunk?
OK.
Richard.
> Thanks.
>
>
> H.J.
> ---
> gcc/
>
> PR target/86560
> * config/i386/i386.c (rest_of_insert_endbranch): Lookup
> indirect_return as function type attribute.
> (ix86_attribute_table): Change indirect_return to function
> type attribute.
> * doc/extend.texi: Update indirect_return attribute.
>
> gcc/testsuite/
>
> PR target/86560
> * gcc.target/i386/pr86560-1.c: New test.
> * gcc.target/i386/pr86560-2.c: Likewise.
> * gcc.target/i386/pr86560-3.c: Likewise.
> ---
> gcc/config/i386/i386.c | 23 +++++++++++++++--------
> gcc/doc/extend.texi | 5 +++--
> gcc/testsuite/gcc.target/i386/pr86560-1.c | 16 ++++++++++++++++
> gcc/testsuite/gcc.target/i386/pr86560-2.c | 16 ++++++++++++++++
> gcc/testsuite/gcc.target/i386/pr86560-3.c | 17 +++++++++++++++++
> 5 files changed, 67 insertions(+), 10 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr86560-1.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr86560-2.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr86560-3.c
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index aec739c3974..ac27248370b 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -2627,16 +2627,23 @@ rest_of_insert_endbranch (void)
> {
> rtx call = get_call_rtx_from (insn);
> rtx fnaddr = XEXP (call, 0);
> + tree fndecl = NULL_TREE;
>
> /* Also generate ENDBRANCH for non-tail call which
> may return via indirect branch. */
> - if (MEM_P (fnaddr)
> - && GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF)
> + if (GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF)
> + fndecl = SYMBOL_REF_DECL (XEXP (fnaddr, 0));
> + if (fndecl == NULL_TREE)
> + fndecl = MEM_EXPR (fnaddr);
> + if (fndecl
> + && TREE_CODE (TREE_TYPE (fndecl)) != FUNCTION_TYPE
> + && TREE_CODE (TREE_TYPE (fndecl)) != METHOD_TYPE)
> + fndecl = NULL_TREE;
> + if (fndecl && TYPE_ARG_TYPES (TREE_TYPE (fndecl)))
> {
> - tree fndecl = SYMBOL_REF_DECL (XEXP (fnaddr, 0));
> - if (fndecl
> - && lookup_attribute ("indirect_return",
> - DECL_ATTRIBUTES (fndecl)))
> + tree fntype = TREE_TYPE (fndecl);
> + if (lookup_attribute ("indirect_return",
> + TYPE_ATTRIBUTES (fntype)))
> need_endbr = true;
> }
> }
> @@ -46101,8 +46108,8 @@ static const struct attribute_spec
> ix86_attribute_table[] =
> ix86_handle_fndecl_attribute, NULL },
> { "function_return", 1, 1, true, false, false, false,
> ix86_handle_fndecl_attribute, NULL },
> - { "indirect_return", 0, 0, true, false, false, false,
> - ix86_handle_fndecl_attribute, NULL },
> + { "indirect_return", 0, 0, false, true, true, false,
> + NULL, NULL },
>
> /* End element. */
> { NULL, 0, 0, false, false, false, false, NULL, NULL }
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index 8b4d3fd9de3..edeaec6d872 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -5861,8 +5861,9 @@ foo (void)
> @item indirect_return
> @cindex @code{indirect_return} function attribute, x86
>
> -The @code{indirect_return} attribute on a function is used to inform
> -the compiler that the function may return via indirect branch.
> +The @code{indirect_return} attribute can be applied to a function,
> +as well as variable or type of function pointer to inform the
> +compiler that the function may return via indirect branch.
>
> @end table
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr86560-1.c
> b/gcc/testsuite/gcc.target/i386/pr86560-1.c
> new file mode 100644
> index 00000000000..a2b702695c5
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr86560-1.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fcf-protection" } */
> +/* { dg-final { scan-assembler-times {\mendbr} 2 } } */
> +
> +struct ucontext;
> +
> +extern int (*bar) (struct ucontext *)
> + __attribute__((__indirect_return__));
> +
> +extern int res;
> +
> +void
> +foo (struct ucontext *oucp)
> +{
> + res = bar (oucp);
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr86560-2.c
> b/gcc/testsuite/gcc.target/i386/pr86560-2.c
> new file mode 100644
> index 00000000000..6f01b385afd
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr86560-2.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fcf-protection" } */
> +/* { dg-final { scan-assembler-times {\mendbr} 2 } } */
> +
> +struct ucontext;
> +
> +typedef int (*bar_p) (struct ucontext *)
> + __attribute__((__indirect_return__));
> +
> +extern int res;
> +
> +void
> +foo (bar_p bar, struct ucontext *oucp)
> +{
> + res = bar (oucp);
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr86560-3.c
> b/gcc/testsuite/gcc.target/i386/pr86560-3.c
> new file mode 100644
> index 00000000000..05328e24509
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr86560-3.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fcf-protection" } */
> +/* { dg-final { scan-assembler-times {\mendbr} 2 } } */
> +
> +struct ucontext;
> +
> +extern int (*bar) (struct ucontext *);
> +
> +extern int res;
> +
> +void
> +foo (struct ucontext *oucp)
> +{
> + int (*f) (struct ucontext *) __attribute__((__indirect_return__))
> + = bar;
> + res = f (oucp);
> +}
> --
> 2.17.1
>
