PING [PATCH] x86: Add ix86_ifunc_ref_local_ok

["H.J. Lu" <hjl.tools@gmail.com>]

On Thu, Jul 21, 2022 at 11:53 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> We can't always use the PLT entry as the function address for local IFUNC
> functions.  When the PIC register is needed for PLT call, indirect call
> via the PLT entry will fail since the PIC register may not be set up
> properly for indirect call.  Add ix86_ifunc_ref_local_ok to return false
> when the PLT entry can't be used as local IFUNC function pointers.
>
> gcc/
>
>         PR target/83782
>         * config/i386/i386.cc (ix86_ifunc_ref_local_ok): New.
>         (TARGET_IFUNC_REF_LOCAL_OK): Use it.
>
> gcc/testsuite/
>
>         PR target/83782
>         * gcc.target/i386/pr83782-1.c: Require non-ia32.
>         * gcc.target/i386/pr83782-2.c: Likewise.
>         * gcc.target/i386/pr83782-3.c: New test.
> ---
>  gcc/config/i386/i386.cc                   | 15 ++++++++++-
>  gcc/testsuite/gcc.target/i386/pr83782-1.c |  8 +++---
>  gcc/testsuite/gcc.target/i386/pr83782-2.c |  4 +--
>  gcc/testsuite/gcc.target/i386/pr83782-3.c | 32 +++++++++++++++++++++++
>  4 files changed, 50 insertions(+), 9 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr83782-3.c
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index e03f86d4a23..5e30dc884bf 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -16070,6 +16070,19 @@ ix86_call_use_plt_p (rtx call_op)
>    return true;
>  }
>
> +/* Implement TARGET_IFUNC_REF_LOCAL_OK.  If this hook returns true,
> +   the PLT entry will be used as the function address for local IFUNC
> +   functions.  When the PIC register is needed for PLT call, indirect
> +   call via the PLT entry will fail since the PIC register may not be
> +   set up properly for indirect call.  In this case, we should return
> +   false.  */
> +
> +static bool
> +ix86_ifunc_ref_local_ok (void)
> +{
> +  return !flag_pic || (TARGET_64BIT && ix86_cmodel != CM_LARGE_PIC);
> +}
> +
>  /* Return true if the function being called was marked with attribute
>     "noplt" or using -fno-plt and we are compiling for non-PIC.  We need
>     to handle the non-PIC case in the backend because there is no easy
> @@ -24953,7 +24966,7 @@ ix86_libgcc_floating_mode_supported_p
>    ix86_get_multilib_abi_name
>
>  #undef TARGET_IFUNC_REF_LOCAL_OK
> -#define TARGET_IFUNC_REF_LOCAL_OK hook_bool_void_true
> +#define TARGET_IFUNC_REF_LOCAL_OK ix86_ifunc_ref_local_ok
>
>  #if !TARGET_MACHO && !TARGET_DLLIMPORT_DECL_ATTRIBUTES
>  # undef TARGET_ASM_RELOC_RW_MASK
> diff --git a/gcc/testsuite/gcc.target/i386/pr83782-1.c b/gcc/testsuite/gcc.target/i386/pr83782-1.c
> index ce97b12e65d..85674346aec 100644
> --- a/gcc/testsuite/gcc.target/i386/pr83782-1.c
> +++ b/gcc/testsuite/gcc.target/i386/pr83782-1.c
> @@ -1,4 +1,4 @@
> -/* { dg-do compile } */
> +/* { dg-do compile { target { ! ia32 } } } */
>  /* { dg-require-ifunc "" } */
>  /* { dg-options "-O2 -fpic" } */
>
> @@ -20,7 +20,5 @@ bar(void)
>    return foo;
>  }
>
> -/* { dg-final { scan-assembler {leal[ \t]foo@GOTOFF\(%[^,]*\),[ \t]%eax} { target ia32 } } } */
> -/* { dg-final { scan-assembler {lea(?:l|q)[ \t]foo\(%rip\),[ \t]%(?:e|r)ax} { target { ! ia32 } } } } */
> -/* { dg-final { scan-assembler-not "foo@GOT\\\(" { target ia32 } } } */
> -/* { dg-final { scan-assembler-not "foo@GOTPCREL\\\(" { target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler {lea(?:l|q)[ \t]foo\(%rip\),[ \t]%(?:e|r)ax} } } */
> +/* { dg-final { scan-assembler-not "foo@GOTPCREL\\\(" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr83782-2.c b/gcc/testsuite/gcc.target/i386/pr83782-2.c
> index e25d258bbda..a654ded771f 100644
> --- a/gcc/testsuite/gcc.target/i386/pr83782-2.c
> +++ b/gcc/testsuite/gcc.target/i386/pr83782-2.c
> @@ -1,4 +1,4 @@
> -/* { dg-do compile } */
> +/* { dg-do compile { target { ! ia32 } } } */
>  /* { dg-require-ifunc "" } */
>  /* { dg-options "-O2 -fpic" } */
>
> @@ -20,7 +20,5 @@ bar(void)
>    return foo;
>  }
>
> -/* { dg-final { scan-assembler {leal[ \t]foo@GOTOFF\(%[^,]*\),[ \t]%eax} { target ia32 } } } */
>  /* { dg-final { scan-assembler {lea(?:l|q)[ \t]foo\(%rip\),[ \t]%(?:e|r)ax} { target { ! ia32 } } } } */
> -/* { dg-final { scan-assembler-not "foo@GOT\\\(" { target ia32 } } } */
>  /* { dg-final { scan-assembler-not "foo@GOTPCREL\\\(" { target { ! ia32 } } } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr83782-3.c b/gcc/testsuite/gcc.target/i386/pr83782-3.c
> new file mode 100644
> index 00000000000..1536481cb79
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr83782-3.c
> @@ -0,0 +1,32 @@
> +/* { dg-do run }  */
> +/* { dg-require-ifunc "" } */
> +/* { dg-require-effective-target pie } */
> +/* { dg-options "-fpie -pie" } */
> +
> +#include <stdio.h>
> +
> +static int __attribute__((noinline))
> +implementation (void)
> +{
> +  printf ("'ere I am JH\n");
> +  return 0;
> +}
> +
> +static __typeof__ (implementation) *resolver (void)
> +{
> +  return (void *)implementation;
> +}
> +
> +extern int magic (void) __attribute__ ((ifunc ("resolver")));
> +
> +__attribute__ ((weak))
> +int
> +call_magic (int (*ptr) (void))
> +{
> +  return ptr ();
> +}
> +
> +int main ()
> +{
> +  return call_magic (magic);
> +}
> --
> 2.36.1
>

PING.

-- 
H.J.