Hi, Gentle ping...
BR, Jeff (Jiufu Guo) Jiufu Guo via Gcc-patches <gcc-patches@gcc.gnu.org> writes: > Hi, > > Gentle ping... > > BR, > Jeff (Jiufu Guo) > > Jiufu Guo <guoji...@linux.ibm.com> writes: > >> Hi, >> >> If a constant is possible to be rotated to/from a positive or negative >> value which "li" can generated, then "li;rotldi" can be used to build >> the constant. >> >> Compare with the previous version: >> https://gcc.gnu.org/pipermail/gcc-patches/2023-July/623528.html >> This patch just did minor changes to the comments according to previous >> review. >> >> Bootstrap and regtest pass on ppc64{,le}. >> >> Is this ok for trunk? >> >> >> BR, >> Jeff (Jiufu) >> >> gcc/ChangeLog: >> >> * config/rs6000/rs6000.cc (can_be_built_by_li_and_rotldi): New function. >> (rs6000_emit_set_long_const): Call can_be_built_by_li_and_rotldi. >> >> gcc/testsuite/ChangeLog: >> >> * gcc.target/powerpc/const-build.c: New test. >> --- >> gcc/config/rs6000/rs6000.cc | 47 +++++++++++++-- >> .../gcc.target/powerpc/const-build.c | 57 +++++++++++++++++++ >> 2 files changed, 98 insertions(+), 6 deletions(-) >> create mode 100644 gcc/testsuite/gcc.target/powerpc/const-build.c >> >> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc >> index 42f49e4a56b..acc332acc05 100644 >> --- a/gcc/config/rs6000/rs6000.cc >> +++ b/gcc/config/rs6000/rs6000.cc >> @@ -10258,6 +10258,31 @@ rs6000_emit_set_const (rtx dest, rtx source) >> return true; >> } >> >> +/* 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 the mask operand of rotldi(rldicl), 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) >> +{ >> + /* If C or ~C contains at least 49 successive zeros, then C can be rotated >> + to/from a positive or negative value that 'li' is able to load. */ >> + int n; >> + if (can_be_rotated_to_lowbits (c, 15, &n) >> + || can_be_rotated_to_lowbits (~c, 15, &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. */ >> @@ -10266,15 +10291,14 @@ 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))) >> @@ -10305,6 +10329,17 @@ 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)); >> + emit_move_insn (dest, temp); >> + } >> else if (ud3 == 0 && ud4 == 0) >> { >> temp = !can_create_pseudo_p () ? dest : gen_reg_rtx (DImode); >> diff --git a/gcc/testsuite/gcc.target/powerpc/const-build.c >> b/gcc/testsuite/gcc.target/powerpc/const-build.c >> new file mode 100644 >> index 00000000000..69b37e2bb53 >> --- /dev/null >> +++ b/gcc/testsuite/gcc.target/powerpc/const-build.c >> @@ -0,1 +1,57 @@ >> +/* { dg-do run } */ >> +/* { dg-options "-O2 -save-temps" } */ >> +/* { dg-require-effective-target has_arch_ppc64 } */ >> + >> +/* Verify that two instructions are successfully used to build constants. >> + One insn is li, another is rotate: rldicl. */ >> + >> +#define NOIPA __attribute__ ((noipa)) >> + >> +struct fun >> +{ >> + long long (*f) (void); >> + long long val; >> +}; >> + >> +long long NOIPA >> +li_rotldi_1 (void) >> +{ >> + return 0x7531000000000LL; >> +} >> + >> +long long NOIPA >> +li_rotldi_2 (void) >> +{ >> + return 0x2100000000000064LL; >> +} >> + >> +long long NOIPA >> +li_rotldi_3 (void) >> +{ >> + return 0xffff8531ffffffffLL; >> +} >> + >> +long long NOIPA >> +li_rotldi_4 (void) >> +{ >> + return 0x21ffffffffffff94LL; >> +} >> + >> +struct fun arr[] = { >> + {li_rotldi_1, 0x7531000000000LL}, >> + {li_rotldi_2, 0x2100000000000064LL}, >> + {li_rotldi_3, 0xffff8531ffffffffLL}, >> + {li_rotldi_4, 0x21ffffffffffff94LL}, >> +}; >> + >> +/* { dg-final { scan-assembler-times {\mrotldi\M} 4 } } */ >> + >> +int >> +main () >> +{ >> + for (int i = 0; i < sizeof (arr) / sizeof (arr[0]); i++) >> + if ((*arr[i].f) () != arr[i].val) >> + __builtin_abort (); >> + >> + return 0; >> +}
