Re: [PATCH] arm: Implement arm Function target attribute 'branch-protection'

[Andrea Corallo <andrea.corallo@arm.com>]

Andrea Corallo <andrea.corallo@arm.com> writes:

> gcc/
>
> 	* config/arm/arm.cc (arm_valid_target_attribute_rec): Add ARM function
> 	attribute 'branch-protection' and parse its options.
> 	* doc/extend.texi: Document ARM Function attribute 'branch-protection'.
>
> gcc/testsuite/
>
> 	* gcc.target/arm/acle/pacbti-m-predef-13.c: New test.
>
> Co-Authored-By: Tejas Belagod  <tbelagod@arm.com>
> ---
>  gcc/config/arm/arm.cc                         | 16 ++++++++
>  gcc/doc/extend.texi                           |  7 ++++
>  .../gcc.target/arm/acle/pacbti-m-predef-13.c  | 41 +++++++++++++++++++
>  3 files changed, 64 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-13.c
>
> diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
> index efc48349dd3..add33090f18 100644
> --- a/gcc/config/arm/arm.cc
> +++ b/gcc/config/arm/arm.cc
> @@ -33568,6 +33568,22 @@ arm_valid_target_attribute_rec (tree args, struct gcc_options *opts)
>  
>  	  opts->x_arm_arch_string = xstrndup (arch, strlen (arch));
>  	}
> +      else if (startswith (q, "branch-protection="))
> +	{
> +	  char *bp_str = q + strlen ("branch-protection=");
> +
> +	  opts->x_arm_branch_protection_string
> +	    = xstrndup (bp_str, strlen (bp_str));
> +
> +	  /* Capture values from target attribute.  */
> +	  aarch_validate_mbranch_protection
> +	    (opts->x_arm_branch_protection_string);
> +
> +	  /* Init function target attr values.  */
> +	  opts->x_aarch_ra_sign_scope = aarch_ra_sign_scope;
> +	  opts->x_aarch_enable_bti = aarch_enable_bti;
> +
> +	}
>        else if (q[0] == '+')
>  	{
>  	  opts->x_arm_arch_string
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index 4a89a3eae7c..23ee43919dd 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -4492,6 +4492,13 @@ 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}.
>  
> +@item branch-protection=
> +@cindex @code{branch-protection=} function attribute, arm
> +Select the function scope on which branch protection will be applied.
> +The behavior and permissible arguments are the same as for the
> +command-line option @option{-mbranch-protection=}.  The default value
> +is @code{none}.
> +
>  @end table
>  
>  The above target attributes can be specified as follows:
> diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-13.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-13.c
> new file mode 100644
> index 00000000000..b6d2df53072
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-13.c
> @@ -0,0 +1,41 @@
> +/* { dg-do compile } */
> +/* { dg-require-effective-target mbranch_protection_ok } */
> +/* { dg-options "-march=armv8.1-m.main+fp -mbranch-protection=pac-ret+leaf -mfloat-abi=hard --save-temps" } */
> +/* { dg-final { check-function-bodies "**" "" } } */
> +
> +#if defined (__ARM_FEATURE_BTI_DEFAULT)
> +#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be undefined."
> +#endif
> +
> +#if !defined (__ARM_FEATURE_PAC_DEFAULT)
> +#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
> +#endif
> +
> +/*
> +**foo:
> +**	bti
> +**	...
> +*/
> +__attribute__((target("branch-protection=pac-ret+bti"), noinline))
> +int foo ()
> +{
> +  return 3;
> +}
> +
> +/*
> +**main:
> +**	pac	ip, lr, sp
> +**	...
> +**	aut	ip, lr, sp
> +**	bx	lr
> +*/
> +int
> +main()
> +{
> +  return 1 + foo ();
> +}
> +
> +/* { dg-final { scan-assembler "\.eabi_attribute 50, 1" } } */
> +/* { dg-final { scan-assembler "\.eabi_attribute 52, 1" } } */
> +/* { dg-final { scan-assembler-not "\.eabi_attribute 74" } } */
> +/* { dg-final { scan-assembler "\.eabi_attribute 76, 1" } } */

Ping

  Andrea