On 12/10/26 3:35 PM, Avinash Jayakar wrote:
> Hi,
>
> Addressed the comments in
> https://gcc.gnu.org/pipermail/gcc-patches/2026-October/733494.html
>
> Changes from v1:
> - Correct commit message.
> - Update the max value of the type size properly.
> - Update type of mode_to_unit_size fn, which uses the updated array.
Not just the uses of mode_unit_size[], but all the uses of GET_MODE_UNIT_SIZE
too need to be
checked to confirm that correct type is used. Please check the code, if not
already done.
- Surya
>
> Bootstrapped and regtested on {x86_64,powerpc64le}-linux-gnu. Ok for
> trunk?
>
> Thanks,
> Avinash
>
> The mode_unit_size array that is generated from
> emit_mode_unit_size_inline function currently hard codes the type of
> this array to unsigned char, since for most architectures the
> mode_unit_size never exceeded 255.
>
> For rs6000 however, we add an opaque mode with 256 bytes which overflows
> this type. Therefore this patch adds a macro named MODE_UNIT_SIZE_TYPE
> in the generated file which is defined based on the maximum value that
> the mode_unit_size array will hold.
> if < 256, unsigned char
> else if < 2^16, unsigned short
> else, unsigned int
>
> 2026-10-12 Avinash Jayakar <[email protected]>
>
> gcc/ChangeLog:
> * genmodes.cc (emit_mode_unit_size): Generate MODE_UNIT_SIZE_TYPE
> macro based on values in mode_unit_size.
> * machmode.h: Use the new macro.
> ---
> gcc/genmodes.cc | 21 ++++++++++++++++++---
> gcc/machmode.h | 4 ++--
> 2 files changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/genmodes.cc b/gcc/genmodes.cc
> index fa5f8923519..ed8bfd3ba3a 100644
> --- a/gcc/genmodes.cc
> +++ b/gcc/genmodes.cc
> @@ -1167,16 +1167,31 @@ emit_mode_unit_size_inline (void)
> int c;
> struct mode_data *m;
>
> + unsigned int max_type_size = 0;
> + for_all_modes (c, m)
> + {
> + unsigned int type_size = (c != MODE_PARTIAL_INT && m->component)
> + ? m->component->bytesize : m->bytesize;
> + if (max_type_size < type_size)
> + max_type_size = type_size;
> + }
> + if (max_type_size < (1 << 8))
> + puts ("#define MODE_UNIT_SIZE_TYPE unsigned char\n");
> + else if (max_type_size < (1 << 16))
> + puts ("#define MODE_UNIT_SIZE_TYPE unsigned short\n");
> + else
> + puts ("#define MODE_UNIT_SIZE_TYPE unsigned int\n");
> +
> puts ("\
> #ifdef __cplusplus\n\
> inline __attribute__((__always_inline__))\n\
> #else\n\
> extern __inline__ __attribute__((__always_inline__, __gnu_inline__))\n\
> #endif\n\
> -unsigned char\n\
> +MODE_UNIT_SIZE_TYPE\n\
> mode_unit_size_inline (machine_mode mode)\n\
> {\n\
> - extern CONST_MODE_UNIT_SIZE unsigned char
> mode_unit_size[NUM_MACHINE_MODES];\
> + extern CONST_MODE_UNIT_SIZE MODE_UNIT_SIZE_TYPE
> mode_unit_size[NUM_MACHINE_MODES];\
> \n\
> gcc_assert (mode >= 0 && mode < NUM_MACHINE_MODES);\n\
> switch (mode)\n\
> @@ -1683,7 +1698,7 @@ emit_mode_unit_size (void)
> int c;
> struct mode_data *m;
>
> - print_maybe_const_decl ("%sunsigned char", "mode_unit_size",
> + print_maybe_const_decl ("%sMODE_UNIT_SIZE_TYPE", "mode_unit_size",
> "NUM_MACHINE_MODES", adj_bytesize);
>
> for_all_modes (c, m)
> diff --git a/gcc/machmode.h b/gcc/machmode.h
> index bc564d6bc13..fa439714bcb 100644
> --- a/gcc/machmode.h
> +++ b/gcc/machmode.h
> @@ -26,7 +26,7 @@ extern CONST_MODE_SIZE poly_uint16
> mode_size[NUM_MACHINE_MODES];
> extern CONST_MODE_PRECISION poly_uint16 mode_precision[NUM_MACHINE_MODES];
> extern const unsigned short mode_inner[NUM_MACHINE_MODES];
> extern CONST_MODE_NUNITS poly_uint16 mode_nunits[NUM_MACHINE_MODES];
> -extern CONST_MODE_UNIT_SIZE unsigned char mode_unit_size[NUM_MACHINE_MODES];
> +extern CONST_MODE_UNIT_SIZE MODE_UNIT_SIZE_TYPE
> mode_unit_size[NUM_MACHINE_MODES];
> extern const unsigned short mode_unit_precision[NUM_MACHINE_MODES];
> extern const unsigned short mode_next[NUM_MACHINE_MODES];
> extern const unsigned short mode_wider[NUM_MACHINE_MODES];
> @@ -611,7 +611,7 @@ mode_to_inner (machine_mode mode)
>
> /* Return the base GET_MODE_UNIT_SIZE value for MODE. */
>
> -ALWAYS_INLINE unsigned char
> +ALWAYS_INLINE MODE_UNIT_SIZE_TYPE
> mode_to_unit_size (machine_mode mode)
> {
> #if GCC_VERSION >= 4001
