Hi Richi,
on 2024/6/3 14:49, Richard Biener wrote:
> On Mon, Jun 3, 2024 at 5:02 AM Kewen Lin <li...@linux.ibm.com> wrote:
>>
>> Currently how we determine which mode will be used for a
>> floating point type is that for a given type precision
>> (size) call mode_for_size to get the first mode which has
>> this size in the specified class. On Powerpc, we have
>> three modes (TF/KF/IF) having the same mode precision 128
>> (see[1]), so the processing forces us to have to place TF
>> at the first place, it would require us to make more
>> adjustment in some generic code to avoid some unexpected
>> mode conversions and it would be even worse if we get rid
>> of TF eventually one day. And as Joseph pointed out in [2],
>> "floating types should have their mode, not a poorly
>> defined precision value", as Joseph and Richi suggested,
>> this patch is to introduce one hook mode_for_floating_type
>> which returns the corresponding mode for type float, double
>> or long double. The default implementation returns SFmode
>> for float and DFmode for double or long double. For ports
>> which need special treatment, there are some other patches
>> for their own port specific implementation (referring to
>> how {,LONG_}DOUBLE_TYPE_SIZE get used there). For all
>> generic uses of {FLOAT,{,LONG_}DOUBLE}_TYPE_SIZE, depending
>> on the context, some of them are replaced with TYPE_PRECISION
>> of the according type node, some other are replaced with
>> GET_MODE_PRECISION on the mode from mode_for_floating_type.
>> This patch also poisons {FLOAT,{,LONG_}DOUBLE}_TYPE_SIZE,
>> so most defines of {FLOAT,{,LONG_}DOUBLE}_TYPE_SIZE in port
>> specific are removed, but there are still some which are
>> good to be kept for readability then they get renamed with
>> port specific prefix.
>>
>> [1] https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651017.html
>> [2] https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651209.html
>>
>> gcc/ChangeLog:
>>
>> * coretypes.h (enum tree_index): Forward declaration.
>> * defaults.h (FLOAT_TYPE_SIZE): Remove.
>> (DOUBLE_TYPE_SIZE): Likewise.
>> (LONG_DOUBLE_TYPE_SIZE): Likewise.
>> * doc/rtl.texi: Update document by replacing {FLOAT,DOUBLE}_TYPE_SIZE
>> with C type {float,double}.
>> * doc/tm.texi.in: Document new hook mode_for_floating_type, remove
>> document entries for {FLOAT,DOUBLE,LONG_DOUBLE}_TYPE_SIZE and
>> update document for WIDEST_HARDWARE_FP_SIZE.
>> * doc/tm.texi: Regenerate.
>> * emit-rtl.cc (init_emit_once): Replace DOUBLE_TYPE_SIZE by
>> calling targetm.c.mode_for_floating_type with TI_DOUBLE_TYPE.
>> * real.h (REAL_VALUE_TO_TARGET_LONG_DOUBLE): Use TYPE_PRECISION of
>> long_double_type_node to replace LONG_DOUBLE_TYPE_SIZE.
>> * system.h (FLOAT_TYPE_SIZE): Poison.
>> (DOUBLE_TYPE_SIZE): Likewise.
>> (LONG_DOUBLE_TYPE_SIZE): Likewise.
>> * target.def (mode_for_floating_type): New hook.
>> * targhooks.cc (default_mode_for_floating_type): New function.
>> (default_scalar_mode_supported_p): Update macros
>> {FLOAT,DOUBLE,LONG_DOUBLE}_TYPE_SIZE by calling
>> targetm.c.mode_for_floating_type with
>> TI_{FLOAT,DOUBLE,LONG_DOUBLE}_TYPE.
>> * targhooks.h (default_mode_for_floating_type): New declaration.
>> * tree-core.h (enum tree_index): Specify underlying type unsigned
>> to sync with forward declaration in coretypes.h.
>> (NUM_FLOATN_TYPES): Explicitly convert to int.
>> (NUM_FLOATNX_TYPES): Likewise.
>> (NUM_FLOATN_NX_TYPES): Likewise.
>> * tree.cc (build_common_tree_nodes): Update macros
>> {FLOAT,DOUBLE,LONG_DOUBLE}_TYPE_SIZE by calling
>> targetm.c.mode_for_floating_type with
>> TI_{FLOAT,DOUBLE,LONG_DOUBLE}_TYPE and set type mode accordingly.
>> ---
>> gcc/coretypes.h | 1 +
>> gcc/defaults.h | 12 ------------
>> gcc/doc/rtl.texi | 2 +-
>> gcc/doc/tm.texi | 33 +++++++++++++--------------------
>> gcc/doc/tm.texi.in | 27 +++++++--------------------
>> gcc/emit-rtl.cc | 3 ++-
>> gcc/real.h | 7 ++++---
>> gcc/system.h | 3 ++-
>> gcc/target.def | 9 +++++++++
>> gcc/targhooks.cc | 18 +++++++++++++++---
>> gcc/targhooks.h | 1 +
>> gcc/tree-core.h | 13 +++++++------
>> gcc/tree.cc | 18 +++++++++++++++---
>> 13 files changed, 77 insertions(+), 70 deletions(-)
>>
>> diff --git a/gcc/coretypes.h b/gcc/coretypes.h
>> index 1ac6f0abea3..00c1c58bd8c 100644
>> --- a/gcc/coretypes.h
>> +++ b/gcc/coretypes.h
>> @@ -100,6 +100,7 @@ struct gimple;
>> typedef gimple *gimple_seq;
>> struct gimple_stmt_iterator;
>> class code_helper;
>> +enum tree_index : unsigned;
>>
>> /* Forward declare rtx_code, so that we can use it in target hooks without
>> needing to pull in rtl.h. */
>> diff --git a/gcc/defaults.h b/gcc/defaults.h
>> index 92f3e07f742..ac2d25852ab 100644
>> --- a/gcc/defaults.h
>> +++ b/gcc/defaults.h
>> @@ -513,18 +513,6 @@ see the files COPYING3 and COPYING.RUNTIME
>> respectively. If not, see
>> #define WCHAR_TYPE_SIZE INT_TYPE_SIZE
>> #endif
>>
>> -#ifndef FLOAT_TYPE_SIZE
>> -#define FLOAT_TYPE_SIZE BITS_PER_WORD
>> -#endif
>> -
>> -#ifndef DOUBLE_TYPE_SIZE
>> -#define DOUBLE_TYPE_SIZE (BITS_PER_WORD * 2)
>> -#endif
>> -
>> -#ifndef LONG_DOUBLE_TYPE_SIZE
>> -#define LONG_DOUBLE_TYPE_SIZE (BITS_PER_WORD * 2)
>> -#endif
>> -
>> #ifndef DECIMAL32_TYPE_SIZE
>> #define DECIMAL32_TYPE_SIZE 32
>> #endif
>> diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
>> index aa10b5235b5..d85b6dcbf1a 100644
>> --- a/gcc/doc/rtl.texi
>> +++ b/gcc/doc/rtl.texi
>> @@ -1326,7 +1326,7 @@ whose size is @code{BITS_PER_WORD}, @code{SImode} on
>> 32-bit machines.
>>
>> The only modes which a machine description @i{must} support are
>> @code{QImode}, and the modes corresponding to @code{BITS_PER_WORD},
>> -@code{FLOAT_TYPE_SIZE} and @code{DOUBLE_TYPE_SIZE}.
>> +C type @code{float} and C type type @code{double}.
>
> type type
Oops, thanks for catching, will fix it.
>
> OK with that fixed and no comments from others.
Thanks!
BR,
Kewen
