Re: [PATCH v2 3/4] LoongArch: Add fscaleb.{s,d} instructions as ldexp{sf,df}3

[Lulu Cheng <chenglulu@loongson.cn>]

在 2022/11/12 下午12:40, Xi Ruoyao 写道:
> On Sat, 2022-11-12 at 11:54 +0800, Lulu Cheng wrote:
>> 在 2022/11/9 下午9:53, Xi Ruoyao 写道:
>>> This allows optimizing __builtin_ldexp{,f} and __builtin_scalbn{,f}
>>> with
>>> -fno-math-errno.
>>>
>>> IMODE is added because we can't hard code SI for operand 2:
>>> fscaleb.d
>>> instruction always take the high half of both source registers into
>>> account.  See my_ldexp_long in the test case.
>>>
>>> gcc/ChangeLog:
>>>
>>>          * config/loongarch/loongarch.md (UNSPEC_FSCALEB): New
>>> unspec.
>>>          (type): Add fscaleb.
>>>          (IMODE): New mode attr.
>>>          (ldexp<mode>3): New instruction template.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>>          * gcc.target/loongarch/fscaleb.c: New test.
>>> ---
>>>    gcc/config/loongarch/loongarch.md            | 26 ++++++++++-
>>>    gcc/testsuite/gcc.target/loongarch/fscaleb.c | 48
>>> ++++++++++++++++++++
>>>    2 files changed, 72 insertions(+), 2 deletions(-)
>>>    create mode 100644 gcc/testsuite/gcc.target/loongarch/fscaleb.c
>>>
>>> diff --git a/gcc/config/loongarch/loongarch.md
>>> b/gcc/config/loongarch/loongarch.md
>>> index eb127c346a3..c141c9adde2 100644
>>> --- a/gcc/config/loongarch/loongarch.md
>>> +++ b/gcc/config/loongarch/loongarch.md
>>> @@ -41,6 +41,7 @@ (define_c_enum "unspec" [
>>>      UNSPEC_FTINT
>>>      UNSPEC_FTINTRM
>>>      UNSPEC_FTINTRP
>>> +  UNSPEC_FSCALEB
>>>    
>>>      ;; Override return address for exception handling.
>>>      UNSPEC_EH_RETURN
>>> @@ -220,6 +221,7 @@ (define_attr "qword_mode" "no,yes"
>>>    ;; fcmp               floating point compare
>>>    ;; fcopysign  floating point copysign
>>>    ;; fcvt               floating point convert
>>> +;; fscaleb     floating point scale
>>>    ;; fsqrt      floating point square root
>>>    ;; frsqrt       floating point reciprocal square root
>>>    ;; multi      multiword sequence (or user asm statements)
>>> @@ -231,8 +233,8 @@ (define_attr "type"
>>>     
>>> "unknown,branch,jump,call,load,fpload,fpidxload,store,fpstore,fpidxs
>>> tore,
>>>       prefetch,prefetchx,condmove,mgtf,mftg,const,arith,logical,
>>>       shift,slt,signext,clz,trap,imul,idiv,move,
>>> -
>>> fmove,fadd,fmul,fmadd,fdiv,frdiv,fabs,fneg,fcmp,fcopysign,fcvt,fsqrt
>>> ,
>>> -   frsqrt,accext,accmod,multi,atomic,syncloop,nop,ghost"
>>> +
>>> fmove,fadd,fmul,fmadd,fdiv,frdiv,fabs,fneg,fcmp,fcopysign,fcvt,fscal
>>> eb,
>>> +   fsqrt,frsqrt,accext,accmod,multi,atomic,syncloop,nop,ghost"
>>>      (cond [(eq_attr "jirl" "!unset") (const_string "call")
>>>           (eq_attr "got" "load") (const_string "load")
>>>    
>>> @@ -418,6 +420,10 @@ (define_mode_attr UNITMODE [(SF "SF") (DF
>>> "DF")])
>>>    ;; the controlling mode.
>>>    (define_mode_attr HALFMODE [(DF "SI") (DI "SI") (TF "DI")])
>>>    
>>> +;; This attribute gives the integer mode that has the same size of
>>> a
>>> +;; floating-point mode.
>>> +(define_mode_attr IMODE [(SF "SI") (DF "DI")])
>>> +
>>>    ;; This code iterator allows signed and unsigned widening
>>> multiplications
>>>    ;; to use the same template.
>>>    (define_code_iterator any_extend [sign_extend zero_extend])
>>> @@ -1014,7 +1020,23 @@ (define_insn "copysign<mode>3"
>>>      "fcopysign.<fmt>\t%0,%1,%2"
>>>      [(set_attr "type" "fcopysign")
>>>       (set_attr "mode" "<UNITMODE>")])
>>> +\f
>>> +;;
>>> +;;  ....................
>>> +;;
>>> +;;     FLOATING POINT SCALE
>>> +;;
>>> +;;  ....................
>>>    
>>> +(define_insn "ldexp<mode>3"
>>> +  [(set (match_operand:ANYF 0 "register_operand" "=f")
>>> +       (unspec:ANYF [(match_operand:ANYF    1 "register_operand"
>>> "f")
>>> +                     (match_operand:<IMODE> 2 "register_operand"
>>> "f")]
>>> +                    UNSPEC_FSCALEB))]
>>> +  "TARGET_HARD_FLOAT"
>>> +  "fscaleb.<fmt>\t%0,%1,%2"
>>> +  [(set_attr "type" "fscaleb")
>>> +   (set_attr "mode" "<UNITMODE>")])
>>>    \f
>>>    ;;
>>>    ;;  ...................
>>> diff --git a/gcc/testsuite/gcc.target/loongarch/fscaleb.c
>>> b/gcc/testsuite/gcc.target/loongarch/fscaleb.c
>>> new file mode 100644
>>> index 00000000000..f18470fbb8f
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.target/loongarch/fscaleb.c
>>> @@ -0,0 +1,48 @@
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -mabi=lp64d -mdouble-float -fno-math-errno" }
>>> */
>>> +/* { dg-final { scan-assembler-times "fscaleb\\.s" 3 } } */
>>> +/* { dg-final { scan-assembler-times "fscaleb\\.d" 4 } } */
>>> +/* { dg-final { scan-assembler-times "slli\\.w" 1 } } */
>>> +
>>> +double
>>> +my_scalbln (double a, long b)
>>> +{
>>> +  return __builtin_scalbln (a, b);
>>> +}
>>> +
>>> +double
>>> +my_scalbn (double a, int b)
>>> +{
>>> +  return __builtin_scalbn (a, b);
>>> +}
>>> +
>>> +
>>> +float
>>> +my_scalblnf (float a, long b)
>>> +{
>>> +  return __builtin_scalblnf (a, b);
>>> +}
>>> +
>>> +float
>>> +my_scalbnf (float a, int b)
>>> +{
>>> +  return __builtin_scalbnf (a, b);
>>> +}
>>> +
>>>
>> I think scalbln/scalblnf/scalbn/scalbnf these four builtin test
>> function
>> with the macro __FLT_RADIX__ control.
>>
>> These functions are tested only if the macro __FLT_RADIX__ has a value
>> of 2.
> LoongArch does not use RESET_FLOAT_FORMAT on SFmode, so __FLT_RADIX__ is
> always 2.
Ok, I have no more questions