Hi David,
David Edelsohn <dje....@gmail.com> writes:
>
> Hi, Jiufu
> * config/rs6000/rs6000.cc (can_be_rotated_to_possitive_li): New
> function.
> (can_be_rotated_to_negative_li): New function.
> (can_be_built_by_li_and_rotldi): New function.
> (rs6000_emit_set_long_const): Call can_be_built_by_li_and_rotldi.
> In English the word "positive" contains one "s", not two. Please correct
> throughout the patches.
> Also a style issue, comments before a function should be followed by a
> blank line.
Sure, I will update accordingly, and check other patches.
>> +/* Check if C can be rotated to a possitive value which 'li' instruction
> positive
>> + is able to load. If so, set *ROT to the number by which C is rotated,
>> + and return true. Return false otherwise. */
> Add a blank line here
>> +static bool
>> +can_be_rotated_to_possitive_li (HOST_WIDE_INT c, int *rot)
> positive
>> +{
>> + /* 49 leading zeros and 15 lowbits on the possitive value
> low bits, positive
Thanks for your careful review!
>> + generated by 'li' instruction. */
>> + return can_be_rotated_to_lowbits (c, 15, rot);
>> +}
>> +/* Check if value C can be built by 2 instructions: one is 'li', another is
>> + rotldi.
>> +
>> + If so, *SHIFT is set to the shift operand of rotldi(rldicl), and *MASK
>> + is set to -1, and return true. Return false otherwise. */
>> +static bool
>> +can_be_built_by_li_and_rotldi (HOST_WIDE_INT c, int *shift,
>> + HOST_WIDE_INT *mask)
>> +{
>> + int n;
>> + if (can_be_rotated_to_possitive_li (c, &n)
>> + || can_be_rotated_to_negative_li (c, &n))
>> + {
>> + *mask = HOST_WIDE_INT_M1;
>> + *shift = HOST_BITS_PER_WIDE_INT - n;
>> + return true;
>> + }
>> +
>> + return false;
>> +}
>> +
>> /* Subroutine of rs6000_emit_set_const, handling PowerPC64 DImode.
>> Output insns to set DEST equal to the constant C as a series of
>> lis, ori and shl instructions. */
>> @@ -10246,15 +10285,14 @@ static void
>> rs6000_emit_set_long_const (rtx dest, HOST_WIDE_INT c)
>> {
>> rtx temp;
>> + int shift;
>> + HOST_WIDE_INT mask;
>> HOST_WIDE_INT ud1, ud2, ud3, ud4;
>>
>> ud1 = c & 0xffff;
>> - c = c >> 16;
>> - ud2 = c & 0xffff;
>> - c = c >> 16;
>> - ud3 = c & 0xffff;
>> - c = c >> 16;
>> - ud4 = c & 0xffff;
>> + ud2 = (c >> 16) & 0xffff;
>> + ud3 = (c >> 32) & 0xffff;
>> + ud4 = (c >> 48) & 0xffff;
>>
>> if ((ud4 == 0xffff && ud3 == 0xffff && ud2 == 0xffff && (ud1 & 0x8000))
>> || (ud4 == 0 && ud3 == 0 && ud2 == 0 && ! (ud1 & 0x8000)))
>> @@ -10278,6 +10316,19 @@ rs6000_emit_set_long_const (rtx dest, HOST_WIDE_INT
>> c)
>> emit_move_insn (dest, gen_rtx_XOR (DImode, temp,
>> GEN_INT ((ud2 ^ 0xffff) << 16)));
>> }
>> + else if (can_be_built_by_li_and_rotldi (c, &shift, &mask))
>> + {
>> + temp = !can_create_pseudo_p () ? dest : gen_reg_rtx (DImode);
>> + unsigned HOST_WIDE_INT imm = (c | ~mask);
>> + imm = (imm >> shift) | (imm << (HOST_BITS_PER_WIDE_INT - shift));
>> +
>> + emit_move_insn (temp, GEN_INT (imm));
>> + if (shift != 0)
>> + temp = gen_rtx_ROTATE (DImode, temp, GEN_INT (shift));
>> + if (mask != HOST_WIDE_INT_M1)
> How is mask != HOST_WIDE_INT_M1? The call to can_by_built_by_li_and_rotldi()
> set it
> to that value and it is not modified in the interim statements.
Oh, Thanks for catching this!
Actually this line is shared for these patches.
"if (mask != HOST_WIDE_INT_M1)" is useful with patch [3/4], and it
should be merged into that patch.
Thanks again for your review!
>> + temp = gen_rtx_AND (DImode, temp, GEN_INT (mask));
>> + emit_move_insn (dest, temp);
>> + }
>> else if (ud3 == 0 && ud4 == 0)
>> {
>> temp = !can_create_pseudo_p () ? dest : gen_reg_rtx (DImode);
> Thanks, David
