On Tue, May 10, 2022 at 9:25 AM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> Mark a function with SYMBOL_FLAG_FUNCTION_ENDBR when inserting ENDBR at
> function entry. Skip the 4-byte ENDBR when emitting a direct call/jmp
> to a local function with ENDBR at function entry.
>
> This has been tested on Linux kernel.
>
> gcc/
>
> PR target/102953
> * config/i386/i386-features.cc
> (rest_of_insert_endbr_and_patchable_area): Set
> SYMBOL_FLAG_FUNCTION_ENDBR when inserting ENDBR.
> * config/i386/i386.cc (ix86_print_operand): Skip the 4-byte ENDBR
> when calling the local function with ENDBR at function entry.
> * config/i386/i386.h (SYMBOL_FLAG_FUNCTION_ENDBR): New.
> (SYMBOL_FLAG_FUNCTION_ENDBR_P): Likewise.
>
> gcc/testsuite/
>
> PR target/102953
> * gcc.target/i386/pr102953-1.c: New test.
> * gcc.target/i386/pr102953-2.c: Likewise.
> ---
> gcc/config/i386/i386-features.cc | 2 ++
> gcc/config/i386/i386.cc | 11 +++++++-
> gcc/config/i386/i386.h | 5 ++++
> gcc/testsuite/gcc.target/i386/pr102953-1.c | 25 ++++++++++++++++++
> gcc/testsuite/gcc.target/i386/pr102953-2.c | 30 ++++++++++++++++++++++
> 5 files changed, 72 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr102953-1.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr102953-2.c
>
> diff --git a/gcc/config/i386/i386-features.cc
> b/gcc/config/i386/i386-features.cc
> index 6fe41c3c24f..3ca1131ed59 100644
> --- a/gcc/config/i386/i386-features.cc
> +++ b/gcc/config/i386/i386-features.cc
> @@ -1979,6 +1979,8 @@ rest_of_insert_endbr_and_patchable_area (bool
> need_endbr,
> || (TARGET_DLLIMPORT_DECL_ATTRIBUTES
> && DECL_DLLIMPORT_P (cfun->decl))))
> {
> + rtx symbol = XEXP (DECL_RTL (cfun->decl), 0);
> + SYMBOL_REF_FLAGS (symbol) |= SYMBOL_FLAG_FUNCTION_ENDBR;
> if (crtl->profile && flag_fentry)
> {
> /* Queue ENDBR insertion to x86_function_profiler.
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 86752a6516a..ad1de239bef 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -13787,7 +13787,16 @@ ix86_print_operand (FILE *file, rtx x, int code)
> else if (flag_pic || MACHOPIC_INDIRECT)
> output_pic_addr_const (file, x, code);
> else
> - output_addr_const (file, x);
> + {
> + /* Skip ENDBR when emitting a direct call/jmp to a local
> + function with ENDBR at function entry. */
> + if (code == 'P'
> + && GET_CODE (x) == SYMBOL_REF
> + && SYMBOL_REF_LOCAL_P (x)
> + && SYMBOL_FLAG_FUNCTION_ENDBR_P (x))
> + x = gen_rtx_PLUS (Pmode, x, GEN_INT (4));
> + output_addr_const (file, x);
> + }
> }
> }
>
> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
> index 363082ba47b..7a6317fea57 100644
> --- a/gcc/config/i386/i386.h
> +++ b/gcc/config/i386/i386.h
> @@ -2792,6 +2792,11 @@ extern GTY(()) tree ms_va_list_type_node;
> #define SYMBOL_REF_STUBVAR_P(X) \
> ((SYMBOL_REF_FLAGS (X) & SYMBOL_FLAG_STUBVAR) != 0)
>
> +/* Flag to mark a function with ENDBR at entry. */
> +#define SYMBOL_FLAG_FUNCTION_ENDBR (SYMBOL_FLAG_MACH_DEP << 5)
> +#define SYMBOL_FLAG_FUNCTION_ENDBR_P(X) \
> + ((SYMBOL_REF_FLAGS (X) & SYMBOL_FLAG_FUNCTION_ENDBR) != 0)
> +
> extern void debug_ready_dispatch (void);
> extern void debug_dispatch_window (int);
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr102953-1.c
> b/gcc/testsuite/gcc.target/i386/pr102953-1.c
> new file mode 100644
> index 00000000000..2afad391baf
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr102953-1.c
> @@ -0,0 +1,25 @@
> +/* { dg-do compile { target { ! *-*-darwin* } } } */
> +/* { dg-options "-O2 -fno-pic -fplt -fcf-protection" } */
> +
> +extern int func (int);
> +
> +extern int i;
> +
> +__attribute__ ((noclone, noinline, noipa))
> +static int
> +bar (int x)
> +{
> + if (x == 0)
> + return x;
> + return bar (x - 1) + func (x);
> +}
> +
> +void *
> +foo (void)
> +{
> + i = bar (2);
> + return bar;
> +}
> +
> +/* { dg-final { scan-assembler-times {call\t_?bar\+4\M} 2 } } */
> +/* { dg-final { scan-assembler-times {call\t_?func\M} 1 } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr102953-2.c
> b/gcc/testsuite/gcc.target/i386/pr102953-2.c
> new file mode 100644
> index 00000000000..5b8d517f4f2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr102953-2.c
> @@ -0,0 +1,30 @@
> +/* { dg-do compile { target { ! *-*-darwin* } } } */
> +/* { dg-options "-O2 -fno-pic -fplt -fcf-protection" } */
> +
> +static int bar (int x);
> +extern int func (int);
> +
> +int
> +foo (int i)
> +{
> + return bar (i);
> +}
> +
> +void *
> +bar_p (void)
> +{
> + return bar;
> +}
> +
> +__attribute__ ((noclone, noinline, noipa))
> +static int
> +bar (int x)
> +{
> + if (x == 0)
> + return x;
> + return bar (x - 1) + func (x);
> +}
> +
> +/* { dg-final { scan-assembler-times {call\t_?bar\+4\M} 1 } } */
> +/* { dg-final { scan-assembler-times {jmp\t_?bar\+4\M} 1 } } */
> +/* { dg-final { scan-assembler-times {call\t_?func\M} 1 } } */
> --
> 2.35.1
>
PING.
--
H.J.
