[PATCH] x86: Update 'P' operand modifier for -fno-plt

[Uros Bizjak]

On Thu, Mar 11, 2021 at 11:22 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Update 'P' operand modifier for -fno-plt to support inline assembly
> statements.  In 64-bit, we can always load function address with
> @GOTPCREL.  In 32-bit, we load function address with @GOT only for
> non-PIC since PIC register may not be available at call site.
>
> gcc/
>
>         PR target/99504
>         * config/i386/i386.c (ix86_print_operand): Update 'P' handling
>         for -fno-plt.
>
> gcc/testsuite/
>
>         PR target/99504
>         * gcc.target/i386/pr99530-1.c: New test.
>         * gcc.target/i386/pr99530-2.c: Likewise.
>         * gcc.target/i386/pr99530-3.c: Likewise.
>         * gcc.target/i386/pr99530-4.c: Likewise.
>         * gcc.target/i386/pr99530-5.c: Likewise.
>         * gcc.target/i386/pr99530-6.c: Likewise.
> ---
>  gcc/config/i386/i386.c                    | 33 +++++++++++++++++++++--
>  gcc/testsuite/gcc.target/i386/pr99530-1.c | 11 ++++++++
>  gcc/testsuite/gcc.target/i386/pr99530-2.c | 11 ++++++++
>  gcc/testsuite/gcc.target/i386/pr99530-3.c | 11 ++++++++
>  gcc/testsuite/gcc.target/i386/pr99530-4.c | 11 ++++++++
>  gcc/testsuite/gcc.target/i386/pr99530-5.c | 11 ++++++++
>  gcc/testsuite/gcc.target/i386/pr99530-6.c | 11 ++++++++
>  7 files changed, 97 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-1.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-2.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-3.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-4.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-5.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr99530-6.c
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 2603333f87b..8733fcecf65 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -12701,7 +12701,8 @@ print_reg (rtx x, int code, FILE *file)
>     y -- print "st(0)" instead of "st" as a register.
>     d -- print duplicated register operand for AVX instruction.
>     D -- print condition for SSE cmp instruction.
> -   P -- if PIC, print an @PLT suffix.
> +   P -- if PIC, print an @PLT suffix.  For -fno-plt, load function
> +       address from GOT.
>     p -- print raw symbol name.
>     X -- don't print any sort of PIC '@' suffix for a symbol.
>     & -- print some in-use local-dynamic symbol name.
> @@ -13445,7 +13446,35 @@ ix86_print_operand (FILE *file, rtx x, int code)
>           x = const0_rtx;
>         }
>
> -      if (code != 'P' && code != 'p')
> +      if (code == 'P')
> +       {
> +         if (current_output_insn == NULL_RTX
> +             && (TARGET_64BIT || (!flag_pic && HAVE_AS_IX86_GOT32X))
> +             && !TARGET_PECOFF
> +             && !TARGET_MACHO
> +             && ix86_cmodel != CM_LARGE
> +             && ix86_cmodel != CM_LARGE_PIC
> +             && GET_CODE (x) == SYMBOL_REF
> +             && SYMBOL_REF_FUNCTION_P (x)
> +             && (!flag_plt
> +                 || (SYMBOL_REF_DECL (x)
> +                     && lookup_attribute ("noplt",
> +                                          DECL_ATTRIBUTES (SYMBOL_REF_DECL (x)))))
> +             && !SYMBOL_REF_LOCAL_P (x))
> +           {
> +             /* For inline assembly statement, load function address
> +                from GOT with 'P' operand modifier to avoid PLT.
> +                NB: This works only with call or jmp.  */
> +             const char *xasm;
> +             if (TARGET_64BIT)
> +               xasm = "{*%p0@GOTPCREL(%%rip)|[QWORD PTR %p0@GOTPCREL[rip]]}";
> +             else
> +               xasm = "{*%p0@GOT|[DWORD PTR %p0@GOT]}";
> +             output_asm_insn (xasm, &x);
> +             return;

This should be handled in output_pic_addr_const.

Uros.

> +           }
> +       }
> +      else if (code != 'p')
>         {
>           if (CONST_INT_P (x))
>             {
> diff --git a/gcc/testsuite/gcc.target/i386/pr99530-1.c b/gcc/testsuite/gcc.target/i386/pr99530-1.c
> new file mode 100644
> index 00000000000..080d7cc9399
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr99530-1.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
> +/* { dg-require-effective-target lp64 } */
> +/* { dg-options "-O2 -fpic -mcmodel=large -fno-plt" } */
> +/* { dg-final { scan-assembler-not "foo@GOTPCREL" } } */
> +
> +extern void foo (void);
> +void
> +bar (void)
> +{
> +  asm ("call %P0" : : "X" (foo));
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr99530-2.c b/gcc/testsuite/gcc.target/i386/pr99530-2.c
> new file mode 100644
> index 00000000000..9808957d624
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr99530-2.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
> +/* { dg-require-effective-target lp64 } */
> +/* { dg-options "-O2 -fno-pic -mcmodel=large -fno-plt" } */
> +/* { dg-final { scan-assembler-not "foo@GOTPCREL" } } */
> +
> +extern void foo (void);
> +void
> +bar (void)
> +{
> +  asm ("call %P0" : : "X" (foo));
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr99530-3.c b/gcc/testsuite/gcc.target/i386/pr99530-3.c
> new file mode 100644
> index 00000000000..22fe81b25f2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr99530-3.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
> +/* { dg-options "-O2 -fno-pic -fno-plt" } */
> +/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOT" { target { ia32 && got32x_reloc } } } } */
> +
> +extern void foo (void);
> +void
> +bar (void)
> +{
> +  asm ("call %P0" : : "X" (foo));
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr99530-4.c b/gcc/testsuite/gcc.target/i386/pr99530-4.c
> new file mode 100644
> index 00000000000..aba0b5d7892
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr99530-4.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
> +/* { dg-options "-O2 -fpic -fno-plt" } */
> +/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-not "foo@GOT" { target { ia32 } } } } */
> +
> +extern void foo (void);
> +void
> +bar (void)
> +{
> +  asm ("call %P0" : : "X" (foo));
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr99530-5.c b/gcc/testsuite/gcc.target/i386/pr99530-5.c
> new file mode 100644
> index 00000000000..02c5799d273
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr99530-5.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
> +/* { dg-options "-O2 -fno-pic" } */
> +/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOT" { target { ia32 && got32x_reloc } } } } */
> +
> +extern void foo (void) __attribute__ ((noplt));
> +void
> +bar (void)
> +{
> +  asm ("call %P0" : : "X" (foo));
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr99530-6.c b/gcc/testsuite/gcc.target/i386/pr99530-6.c
> new file mode 100644
> index 00000000000..0dfdd3752f7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr99530-6.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { i?86-*-linux* x86_64-*-linux* } } } */
> +/* { dg-options "-O2 -fpic" } */
> +/* { dg-final { scan-assembler "call\[ \t\]+\[*\]foo@GOTPCREL" { target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-not "foo@GOT" { target { ia32 } } } } */
> +
> +extern void foo (void) __attribute__ ((noplt));
> +void
> +bar (void)
> +{
> +  asm ("call %P0" : : "X" (foo));
> +}
> --
> 2.29.2
>