Ping^3: [PATCH V6] rs6000: Optimize cmp on rotated 16bits constant

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi,

Gentle ping this:
https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600475.html

BR,
Jeff (Jiufu)


Jiufu Guo via Gcc-patches <gcc-patches@gcc.gnu.org> writes:

> Gentle ping:
> https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600475.html
>
> BR,
> Jeff (Jiufu)
>
> Jiufu Guo via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>
>> Ping: https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600475.html
>>
>> BR,
>> Jeff(Jiufu)
>>
>>
>> Jiufu Guo <guojiufu@linux.ibm.com> writes:
>>
>>> Hi,
>>>
>>> When checking eq/ne with a constant which has only 16bits, it can be
>>> optimized to check the rotated data.  By this, the constant building
>>> is optimized.
>>>
>>> As the example in PR103743:
>>> For "in == 0x8000000000000000LL", this patch generates:
>>>         rotldi %r3,%r3,16
>>>         cmpldi %cr0,%r3,32768
>>> instead:
>>>         li %r9,-1
>>>         rldicr %r9,%r9,0,0
>>>         cmpd %cr0,%r3,%r9
>>>
>>> Compare with previous patchs:
>>> https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600385.html
>>> https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600198.html
>>>
>>> This patch releases the condition on can_create_pseudo_p and adds
>>> clobbers to allow the splitter can be run both before and after RA.
>>>
>>> This is updated patch based on previous patch and comments:
>>> https://gcc.gnu.org/pipermail/gcc-patches/2022-August/600315.html
>>>
>>> This patch pass bootstrap and regtest on ppc64 and ppc64le.
>>> Is it ok for trunk?  Thanks for comments!
>>>
>>> BR,
>>> Jeff(Jiufu)
>>>
>>>
>>> 	PR target/103743
>>>
>>> gcc/ChangeLog:
>>>
>>> 	* config/rs6000/rs6000-protos.h (rotate_from_leading_zeros_const): New.
>>> 	(compare_rotate_immediate_p): New.
>>> 	* config/rs6000/rs6000.cc (rotate_from_leading_zeros_const): New
>>> 	definition.
>>> 	(compare_rotate_immediate_p): New definition.
>>> 	* config/rs6000/rs6000.md (EQNE): New code_attr.
>>> 	(*rotate_on_cmpdi): New define_insn_and_split.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> 	* gcc.target/powerpc/pr103743.c: New test.
>>> 	* gcc.target/powerpc/pr103743_1.c: New test.
>>>
>>> ---
>>>  gcc/config/rs6000/rs6000-protos.h             |  2 +
>>>  gcc/config/rs6000/rs6000.cc                   | 41 ++++++++
>>>  gcc/config/rs6000/rs6000.md                   | 62 +++++++++++-
>>>  gcc/testsuite/gcc.target/powerpc/pr103743.c   | 52 ++++++++++
>>>  gcc/testsuite/gcc.target/powerpc/pr103743_1.c | 95 +++++++++++++++++++
>>>  5 files changed, 251 insertions(+), 1 deletion(-)
>>>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr103743.c
>>>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr103743_1.c
>>>
>>> diff --git a/gcc/config/rs6000/rs6000-protos.h b/gcc/config/rs6000/rs6000-protos.h
>>> index b3c16e7448d..78847e6b3db 100644
>>> --- a/gcc/config/rs6000/rs6000-protos.h
>>> +++ b/gcc/config/rs6000/rs6000-protos.h
>>> @@ -35,6 +35,8 @@ extern bool xxspltib_constant_p (rtx, machine_mode, int *, int *);
>>>  extern int vspltis_shifted (rtx);
>>>  extern HOST_WIDE_INT const_vector_elt_as_int (rtx, unsigned int);
>>>  extern bool macho_lo_sum_memory_operand (rtx, machine_mode);
>>> +extern int rotate_from_leading_zeros_const (unsigned HOST_WIDE_INT, int);
>>> +extern bool compare_rotate_immediate_p (unsigned HOST_WIDE_INT);
>>>  extern int num_insns_constant (rtx, machine_mode);
>>>  extern int small_data_operand (rtx, machine_mode);
>>>  extern bool mem_operand_gpr (rtx, machine_mode);
>>> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
>>> index df491bee2ea..a548db42660 100644
>>> --- a/gcc/config/rs6000/rs6000.cc
>>> +++ b/gcc/config/rs6000/rs6000.cc
>>> @@ -14797,6 +14797,47 @@ rs6000_reverse_condition (machine_mode mode, enum rtx_code code)
>>>      return reverse_condition (code);
>>>  }
>>>  
>>> +/* Check if C can be rotated from an immediate which starts (as 64bit integer)
>>> +   with at least CLZ bits zero.
>>> +
>>> +   Return the number by which C can be rotated from the immediate.
>>> +   Return -1 if C can not be rotated as from.  */
>>> +
>>> +int
>>> +rotate_from_leading_zeros_const (unsigned HOST_WIDE_INT c, int clz)
>>> +{
>>> +  /* case a. 0..0xxx: already at least clz zeros.  */
>>> +  int lz = clz_hwi (c);
>>> +  if (lz >= clz)
>>> +    return 0;
>>> +
>>> +  /* case b. 0..0xxx0..0: at least clz zeros.  */
>>> +  int tz = ctz_hwi (c);
>>> +  if (lz + tz >= clz)
>>> +    return tz;
>>> +
>>> +  /* case c. xx10.....0xx: rotate 'clz + 1' bits firstly, then check case b.
>>> +	       ^bit -> Vbit
>>> +	     00...00xxx100, 'clz + 1' >= bits of xxxx.  */
>>> +  const int rot_bits = HOST_BITS_PER_WIDE_INT - clz + 1;
>>> +  unsigned HOST_WIDE_INT rc = (c >> rot_bits) | (c << (clz - 1));
>>> +  tz = ctz_hwi (rc);
>>> +  if (clz_hwi (rc) + tz >= clz)
>>> +    return tz + rot_bits;
>>> +
>>> +  return -1;
>>> +}
>>> +
>>> +/* Check if C can be rotated from an immediate operand of cmpdi or cmpldi.  */
>>> +
>>> +bool
>>> +compare_rotate_immediate_p (unsigned HOST_WIDE_INT c)
>>> +{
>>> +  /* leading 48 zeros (cmpldi), or leading 49 ones (cmpdi).  */
>>> +  return rotate_from_leading_zeros_const (~c, 49) > 0
>>> +	 || rotate_from_leading_zeros_const (c, 48) > 0;
>>> +}
>>> +
>>>  /* Generate a compare for CODE.  Return a brand-new rtx that
>>>     represents the result of the compare.  */
>>>  
>>> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
>>> index e9e5cd1e54d..cad3cfc98cd 100644
>>> --- a/gcc/config/rs6000/rs6000.md
>>> +++ b/gcc/config/rs6000/rs6000.md
>>> @@ -7766,6 +7766,67 @@ (define_insn "*movsi_from_df"
>>>    "xscvdpsp %x0,%x1"
>>>    [(set_attr "type" "fp")])
>>>  
>>> +
>>> +(define_code_iterator eqne [eq ne])
>>> +(define_code_attr EQNE [(eq "EQ") (ne "NE")])
>>> +
>>> +;; "i == C" ==> "rotl(i,N) == rotl(C,N)"
>>> +(define_insn_and_split "*rotate_on_cmpdi"
>>> +  [(set (pc)
>>> +	(if_then_else (eqne (match_operand:DI 1 "gpc_reg_operand" "r")
>>> +			    (match_operand:DI 2 "const_int_operand" "n"))
>>> +		      (label_ref (match_operand 0 ""))
>>> +		      (pc)))
>>> +  (clobber (match_scratch:DI 3 "=r"))
>>> +  (clobber (match_scratch:CCUNS 4 "=y"))]
>>> +  "TARGET_POWERPC64 && num_insns_constant (operands[2], DImode) > 1
>>> +   && compare_rotate_immediate_p (UINTVAL (operands[2]))"
>>> +   "#"
>>> +   "&& 1"
>>> +  [(pc)]
>>> +{
>>> +  rtx note = find_reg_note (curr_insn, REG_BR_PROB, 0);
>>> +  bool sgn = false;
>>> +  unsigned HOST_WIDE_INT C = INTVAL (operands[2]);
>>> +  int rot = rotate_from_leading_zeros_const (C, 48);
>>> +  if (rot < 0)
>>> +    {
>>> +      sgn = true;
>>> +      rot = rotate_from_leading_zeros_const (~C, 49);
>>> +    }
>>> +  rtx n = GEN_INT (HOST_BITS_PER_WIDE_INT - rot);
>>> +
>>> +  /* i' = rotl (i, n) */
>>> +  rtx op0 = can_create_pseudo_p () ? gen_reg_rtx (DImode) : operands[3];
>>> +  emit_insn (gen_rtx_SET (op0, gen_rtx_ROTATE (DImode, operands[1], n)));
>>> +
>>> +  /* C' = rotl (C, n) */
>>> +  rtx op1 = GEN_INT ((C << INTVAL (n)) | (C >> rot));
>>> +
>>> +  /* i' ==  C' */
>>> +  machine_mode comp_mode = sgn ? CCmode : CCUNSmode;
>>> +  rtx cc = can_create_pseudo_p () ? gen_reg_rtx (comp_mode) : operands[4];
>>> +  PUT_MODE (cc, comp_mode);
>>> +  emit_insn (gen_rtx_SET (cc, gen_rtx_COMPARE (comp_mode, op0, op1)));
>>> +  rtx cmp = gen_rtx_<EQNE> (CCmode, cc, const0_rtx);
>>> +  rtx loc_ref = gen_rtx_LABEL_REF (VOIDmode, operands[0]);
>>> +  emit_jump_insn (gen_rtx_SET (pc_rtx,
>>> +			       gen_rtx_IF_THEN_ELSE (VOIDmode, cmp,
>>> +						     loc_ref, pc_rtx)));
>>> +
>>> +  /* keep the probability info for the prediction of the branch insn.  */
>>> +  if (note)
>>> +    {
>>> +      profile_probability prob
>>> +	= profile_probability::from_reg_br_prob_note (XINT (note, 0));
>>> +
>>> +      add_reg_br_prob_note (get_last_insn (), prob);
>>> +    }
>>> +
>>> +  DONE;
>>> +}
>>> +)
>>> +
>>>  ;; Split a load of a large constant into the appropriate two-insn
>>>  ;; sequence.
>>>  
>>> @@ -13472,7 +13533,6 @@ (define_expand "@ctr<mode>"
>>>  ;; rs6000_legitimate_combined_insn prevents combine creating any of
>>>  ;; the ctr<mode> insns.
>>>  
>>> -(define_code_iterator eqne [eq ne])
>>>  (define_code_attr bd [(eq "bdz") (ne "bdnz")])
>>>  (define_code_attr bd_neg [(eq "bdnz") (ne "bdz")])
>>>  
>>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr103743.c b/gcc/testsuite/gcc.target/powerpc/pr103743.c
>>> new file mode 100644
>>> index 00000000000..abb876ed79e
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.target/powerpc/pr103743.c
>>> @@ -0,0 +1,52 @@
>>> +/* { dg-options "-O2" } */
>>> +/* { dg-do compile { target has_arch_ppc64 } } */
>>> +
>>> +/* { dg-final { scan-assembler-times {\mcmpldi\M} 10  } } */
>>> +/* { dg-final { scan-assembler-times {\mcmpdi\M} 4  } } */
>>> +/* { dg-final { scan-assembler-times {\mrotldi\M} 14  } } */
>>> +
>>> +int foo (int a);
>>> +
>>> +int __attribute__ ((noinline)) udi_fun (unsigned long long in)
>>> +{
>>> +  if (in == (0x8642000000000000ULL))
>>> +    return foo (1);
>>> +  if (in == (0x7642000000000000ULL))
>>> +    return foo (12);
>>> +  if (in == (0x8000000000000000ULL))
>>> +    return foo (32);
>>> +  if (in == (0x8000000000000001ULL))
>>> +    return foo (33);
>>> +  if (in == (0x8642FFFFFFFFFFFFULL))
>>> +    return foo (46);
>>> +  if (in == (0x7642FFFFFFFFFFFFULL))
>>> +    return foo (51);
>>> +  if (in == (0x7567000000ULL))
>>> +    return foo (9);
>>> +  if (in == (0xFFF8567FFFFFFFFFULL))
>>> +    return foo (19);
>>> +
>>> +  return 0;
>>> +}
>>> +
>>> +int __attribute__ ((noinline)) di_fun (long long in)
>>> +{
>>> +  if (in == (0x8642000000000000LL))
>>> +    return foo (1);
>>> +  if (in == (0x7642000000000000LL))
>>> +    return foo (12);
>>> +  if (in == (0x8000000000000000LL))
>>> +    return foo (32);
>>> +  if (in == (0x8000000000000001LL))
>>> +    return foo (33);
>>> +  if (in == (0x8642FFFFFFFFFFFFLL))
>>> +    return foo (46);
>>> +  if (in == (0x7642FFFFFFFFFFFFLL))
>>> +    return foo (51);
>>> +  if (in == (0x7567000000LL))
>>> +    return foo (9);
>>> +  if (in == (0xFFF8567FFFFFFFFFLL))
>>> +    return foo (19);
>>> +
>>> +  return 0;
>>> +}
>>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr103743_1.c b/gcc/testsuite/gcc.target/powerpc/pr103743_1.c
>>> new file mode 100644
>>> index 00000000000..2c08c56714a
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.target/powerpc/pr103743_1.c
>>> @@ -0,0 +1,95 @@
>>> +/* { dg-do run } */
>>> +/* { dg-options "-O2 -std=c99" } */
>>> +
>>> +int
>>> +foo (int a)
>>> +{
>>> +  return a + 6;
>>> +}
>>> +
>>> +int __attribute__ ((noinline)) udi_fun (unsigned long long in)
>>> +{
>>> +  if (in == (0x8642000000000000ULL))
>>> +    return foo (1);
>>> +  if (in == (0x7642000000000000ULL))
>>> +    return foo (12);
>>> +  if (in == (0x8000000000000000ULL))
>>> +    return foo (32);
>>> +  if (in == (0x8000000000000001ULL))
>>> +    return foo (33);
>>> +  if (in == (0x8642FFFFFFFFFFFFULL))
>>> +    return foo (46);
>>> +  if (in == (0x7642FFFFFFFFFFFFULL))
>>> +    return foo (51);
>>> +  if (in == (0x7567000000ULL))
>>> +    return foo (9);
>>> +  if (in == (0xFFF8567FFFFFFFFFULL))
>>> +    return foo (19);
>>> +  
>>> +  return 0;
>>> +}
>>> +
>>> +int __attribute__ ((noinline)) di_fun (long long in)
>>> +{
>>> +  if (in == (0x8642000000000000LL))
>>> +    return foo (1);
>>> +  if (in == (0x7642000000000000LL))
>>> +    return foo (12);
>>> +  if (in == (0x8000000000000000LL))
>>> +    return foo (32);
>>> +  if (in == (0x8000000000000001LL))
>>> +    return foo (33);
>>> +  if (in == (0x8642FFFFFFFFFFFFLL))
>>> +    return foo (46);
>>> +  if (in == (0x7642FFFFFFFFFFFFLL))
>>> +    return foo (51);
>>> +  return 0;
>>> +}
>>> +
>>> +int
>>> +main ()
>>> +{
>>> +  int e = 0;
>>> +  if (udi_fun (6) != 0)
>>> +    e++;
>>> +  if (udi_fun (0x8642000000000000ULL) != foo (1))
>>> +    e++;
>>> +  if (udi_fun (0x7642000000000000ULL) != foo (12))
>>> +    e++;
>>> +  if (udi_fun (0x8000000000000000ULL) != foo (32))
>>> +    e++;
>>> +  if (udi_fun (0x8000000000000001ULL) != foo (33))
>>> +    e++;
>>> +  if (udi_fun (0x8642FFFFFFFFFFFFULL) != foo (46))
>>> +    e++;
>>> +  if (udi_fun (0x7642FFFFFFFFFFFFULL) != foo (51))
>>> +    e++;
>>> +  if (udi_fun (0x7567000000ULL) != foo (9))
>>> +    e++;
>>> +  if (udi_fun (0xFFF8567FFFFFFFFFULL) != foo (19))
>>> +    e++;
>>> +
>>> +  if (di_fun (6) != 0)
>>> +    e++;
>>> +  if (di_fun (0x8642000000000000LL) != foo (1))
>>> +    e++;
>>> +  if (di_fun (0x7642000000000000LL) != foo (12))
>>> +    e++;
>>> +  if (di_fun (0x8000000000000000LL) != foo (32))
>>> +    e++;
>>> +  if (di_fun (0x8000000000000001LL) != foo (33))
>>> +    e++;
>>> +  if (di_fun (0x8642FFFFFFFFFFFFLL) != foo (46))
>>> +    e++;
>>> +  if (di_fun (0x7642FFFFFFFFFFFFLL) != foo (51))
>>> +    e++;
>>> +  if (udi_fun (0x7567000000LL) != foo (9))
>>> +    e++;
>>> +  if (udi_fun (0xFFF8567FFFFFFFFFLL) != foo (19))
>>> +    e++;
>>> +
>>> +  if (e)
>>> +    __builtin_abort ();
>>> +  return 0;
>>> +}
>>> +