On Thu, Jan 11, 2024 at 4:44 AM Fangrui Song <[email protected]> wrote:
>
> Printing the raw symbol is useful in inline asm (e.g. in C++ to get the
> mangled name). Similar constraints are available in other targets (e.g.
> "S" for aarch64/riscv, "Cs" for m68k).
>
> There isn't a good way for x86 yet, e.g. "i" doesn't work for
> PIC/-mcmodel=large. This patch adds "z".
Please use W-prefixed multi-letter constraint name.
Uros.
>
> gcc/ChangeLog:
>
> PR target/105576
> * config/i386/constraints.md: Define constraint 'z'.
> * doc/md.texi: Document it.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/asm-raw-symbol.c: New testcase.
> ---
> gcc/config/i386/constraints.md | 5 ++++-
> gcc/doc/md.texi | 4 ++++
> gcc/testsuite/gcc.target/i386/asm-raw-symbol.c | 13 +++++++++++++
> 3 files changed, 21 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/asm-raw-symbol.c
>
> diff --git a/gcc/config/i386/constraints.md b/gcc/config/i386/constraints.md
> index 0c6e662df25..64330dfdf01 100644
> --- a/gcc/config/i386/constraints.md
> +++ b/gcc/config/i386/constraints.md
> @@ -19,7 +19,6 @@
>
> ;;; Unused letters:
> ;;; H
> -;;; z
>
> ;; Integer register constraints.
> ;; It is not necessary to define 'r' here.
> @@ -438,3 +437,7 @@ (define_constraint "je"
> "@internal constant that do not allow any unspec global offsets"
> (and (match_operand 0 "x86_64_immediate_operand")
> (match_test "!x86_poff_operand_p (op)")))
> +
> +(define_constraint "z"
> + "A symbolic reference or label reference."
> + (match_code "const,symbol_ref,label_ref"))
> diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
> index 47a87d6ceec..bbfec024311 100644
> --- a/gcc/doc/md.texi
> +++ b/gcc/doc/md.texi
> @@ -4286,6 +4286,10 @@ VSIB address operand.
> @item Ts
> Address operand without segment register.
>
> +@item z
> +A symbolic reference or label reference.
> +You can use the @code{%p} modifier to print the raw symbol.
> +
> @end table
>
> @item Xstormy16---@file{config/stormy16/stormy16.h}
> diff --git a/gcc/testsuite/gcc.target/i386/asm-raw-symbol.c
> b/gcc/testsuite/gcc.target/i386/asm-raw-symbol.c
> new file mode 100644
> index 00000000000..ce88f3baee6
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/asm-raw-symbol.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +
> +extern int var;
> +
> +void
> +func (void)
> +{
> + __asm__ ("@ %p0" : : "z" (func));
> + __asm__ ("@ %p0" : : "z" (&var + 1));
> +}
> +
> +/* { dg-final { scan-assembler "@ func" } } */
> +/* { dg-final { scan-assembler "@ var\\+4" } } */
> --
> 2.43.0.275.g3460e3d667-goog
>
