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; > +}
