Hi, If a constant is possible to be rotated to/from a positive or negative value from "li", then "li;rotldi" can be used to build the constant.
Compare with the previous version, those one-line abstraction codes are removed. https://gcc.gnu.org/pipermail/gcc-patches/2023-June/621001.html 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 | 54 +++++++++++++++++++ 2 files changed, 95 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..13aafd1360a 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 -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; + + /* Check if C can be rotated to a positive or negative value + which 'li' instruction is able to load. */ + 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..70f095f6bf2 --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/const-build.c @@ -0,0 +1,54 @@ +/* { dg-do run } */ +/* { dg-options "-O2 -save-temps" } */ +/* { dg-require-effective-target has_arch_ppc64 } */ + +#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; +} -- 2.39.3
