[PATCH 6/9] binutils: Make DWARF register name lookup be via a function pointer

[Palmer Dabbelt via binutils]

On Fri, 22 Nov 2019 04:10:30 PST (-0800), andrew.burgess@embecosm.com wrote:
> Add a layer of indirection for DWARF register name lookup by
> introducing a function pointer.  Right now all targets use the same
> table based implementation that they always have, however, this will
> change in a later commit.
>
> binutils/ChangeLog:
>
> 	* dwarf.c (typedef dwarf_regname_lookup_ftype): New typedef.
> 	(dwarf_regnames_lookup_func): New static global.
> 	(init_dwarf_regnames_i386): Set dwarf_regnames_lookup_func.
> 	(init_dwarf_regnames_iamcu): Likewise.
> 	(init_dwarf_regnames_x86_64): Likewise.
> 	(init_dwarf_regnames_aarch64): Likewise.
> 	(init_dwarf_regnames_s390): Likewise.
> 	(init_dwarf_regnames_riscv): Likewise.
> 	(init_dwarf_regnames_by_elf_machine_code): Reset
> 	dwarf_regnames_lookup_func to NULL.
> 	(init_dwarf_regnames_by_bfd_arch_and_mach): Likewise.
> 	(regname_internal_by_table_only): New function.
> 	(regname): Make use of dwarf_regnames_lookup_func.
>
> Change-Id: Ibbff61c0abea32927f35c9e478793039ab8bb57d
> ---
>  binutils/ChangeLog | 16 ++++++++++++++++
>  binutils/dwarf.c   | 43 +++++++++++++++++++++++++++++++++++--------
>  2 files changed, 51 insertions(+), 8 deletions(-)
>
> diff --git a/binutils/dwarf.c b/binutils/dwarf.c
> index ea6e7eefa86..87ac0562eff 100644
> --- a/binutils/dwarf.c
> +++ b/binutils/dwarf.c
> @@ -38,6 +38,7 @@
>  #define MIN(a, b) ((a) < (b) ? (a) : (b))
>
>  static const char *regname (unsigned int regno, int row);
> +static const char *regname_internal_by_table_only (unsigned int regno);
>
>  static int have_frame_base;
>  static int need_base_address;
> @@ -7360,9 +7361,12 @@ typedef struct Frame_Chunk
>  }
>  Frame_Chunk;
>
> +typedef const char *(*dwarf_regname_lookup_ftype) (unsigned int);
> +static dwarf_regname_lookup_ftype dwarf_regnames_lookup_func;
>  static const char *const *dwarf_regnames;
>  static unsigned int dwarf_regnames_count;
>
> +
>  /* A marker for a col_type that means this column was never referenced
>     in the frame info.  */
>  #define DW_CFA_unreferenced (-1)
> @@ -7469,6 +7473,7 @@ init_dwarf_regnames_i386 (void)
>  {
>    dwarf_regnames = dwarf_regnames_i386;
>    dwarf_regnames_count = ARRAY_SIZE (dwarf_regnames_i386);
> +  dwarf_regnames_lookup_func = regname_internal_by_table_only;
>  }
>
>  static void
> @@ -7476,6 +7481,7 @@ init_dwarf_regnames_iamcu (void)
>  {
>    dwarf_regnames = dwarf_regnames_iamcu;
>    dwarf_regnames_count = ARRAY_SIZE (dwarf_regnames_iamcu);
> +  dwarf_regnames_lookup_func = regname_internal_by_table_only;
>  }
>
>  static const char *const dwarf_regnames_x86_64[] =
> @@ -7515,6 +7521,7 @@ init_dwarf_regnames_x86_64 (void)
>  {
>    dwarf_regnames = dwarf_regnames_x86_64;
>    dwarf_regnames_count = ARRAY_SIZE (dwarf_regnames_x86_64);
> +  dwarf_regnames_lookup_func = regname_internal_by_table_only;
>  }
>
>  static const char *const dwarf_regnames_aarch64[] =
> @@ -7542,6 +7549,7 @@ init_dwarf_regnames_aarch64 (void)
>  {
>    dwarf_regnames = dwarf_regnames_aarch64;
>    dwarf_regnames_count = ARRAY_SIZE (dwarf_regnames_aarch64);
> +  dwarf_regnames_lookup_func = regname_internal_by_table_only;
>  }
>
>  static const char *const dwarf_regnames_s390[] =
> @@ -7566,6 +7574,7 @@ init_dwarf_regnames_s390 (void)
>  {
>    dwarf_regnames = dwarf_regnames_s390;
>    dwarf_regnames_count = ARRAY_SIZE (dwarf_regnames_s390);
> +  dwarf_regnames_lookup_func = regname_internal_by_table_only;
>  }
>
>  static const char *const dwarf_regnames_riscv[] =
> @@ -7587,11 +7596,14 @@ init_dwarf_regnames_riscv (void)
>  {
>    dwarf_regnames = dwarf_regnames_riscv;
>    dwarf_regnames_count = ARRAY_SIZE (dwarf_regnames_riscv);
> +  dwarf_regnames_lookup_func = regname_internal_by_table_only;
>  }
>
>  void
>  init_dwarf_regnames_by_elf_machine_code (unsigned int e_machine)
>  {
> +  dwarf_regnames_lookup_func = NULL;
> +
>    switch (e_machine)
>      {
>      case EM_386:
> @@ -7632,6 +7644,8 @@ void
>  init_dwarf_regnames_by_bfd_arch_and_mach (enum bfd_architecture arch,
>                                            unsigned long mach)
>  {
> +  dwarf_regnames_lookup_func = NULL;
> +
>    switch (arch)
>      {
>      case bfd_arch_i386:
> @@ -7674,18 +7688,31 @@ init_dwarf_regnames_by_bfd_arch_and_mach (enum bfd_architecture arch,
>  }
>
>  static const char *
> -regname (unsigned int regno, int row)
> +regname_internal_by_table_only (unsigned int regno)
>  {
> -  static char reg[64];
> -
> -  if (dwarf_regnames
> +  if (dwarf_regnames != NULL
>        && regno < dwarf_regnames_count
>        && dwarf_regnames [regno] != NULL)
> +    return dwarf_regnames [regno];
> +
> +  return NULL;
> +}
> +
> +static const char *
> +regname (unsigned int regno, int name_only_p)
> +{
> +  static char reg[64];
> +
> +  const char *name = NULL;
> +
> +  if (dwarf_regnames_lookup_func != NULL)
> +    name = dwarf_regnames_lookup_func (regno);
> +
> +  if (name != NULL)
>      {
> -      if (row)
> -	return dwarf_regnames [regno];
> -      snprintf (reg, sizeof (reg), "r%d (%s)", regno,
> -		dwarf_regnames [regno]);
> +      if (name_only_p)
> +	return name;
> +      snprintf (reg, sizeof (reg), "r%d (%s)", regno, name);
>      }
>    else
>      snprintf (reg, sizeof (reg), "r%d", regno);

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>