Segher Boessenkool <seg...@kernel.crashing.org> writes:
> Since times immemorial there has been const_int_rtx for all values from
> -64 to 64, but only constm1_rtx..const2_rtx have been available for
> convenient use. Change this, so that we can use all values in
> {-64,...,64} in RTL easily. This matters, because then we we just say
> if (XEXP (x, 1) == const16_rtx)
> and things like that, since all const_int in that range are unique. We
> already do for -1, 0, 1, 2, but we could for everything.
>
> 2021-06-01 Segher Boessenkool <seg...@kernel.crashing.org>
> * rtl.h (constm64_rtx, ..., constm2_rtx): New.
> (const3_rtx, ..., const64_rtx): New.
>
> doc/
> * rtl.texi (Constants): Document the new names.
> ---
> Tested on powerpc64-linux {-m32,-m64}, but this of course doesn't mean
> all that much until any of the new names are actually used.
>
> Is this okay for trunk?
No strong objection, but personally I'd rather not add something
that is very specific to VOIDmode CONST_INTs. I realise it's very
unlikely that we'll ever be able to give CONST_INTs their proper mode
(no-one has the kind of time needed to do that), but I don't think we
should make the switch actively harder either.
How about adding a new inline helper function that tests whether an
rtx is a CONST_INT with a given value? Then we could have a
__builtin_constant_p shortcut for the [-64, 64] case. That would
also avoid hard-coding the range.
Thanks,
Richard
>
>
> Segher
>
>
> gcc/doc/rtl.texi | 20 +++++----
> gcc/rtl.h | 127
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 137 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
> index 5af71137a878..5dbfb6028095 100644
> --- a/gcc/doc/rtl.texi
> +++ b/gcc/doc/rtl.texi
> @@ -1658,19 +1658,21 @@ copies of the top bit. Note however that values are
> neither
> inherently signed nor inherently unsigned; where necessary, signedness
> is determined by the rtl operation instead.
>
> +@findex constm64_rtx
> +@findex constm1_rtx
> @findex const0_rtx
> @findex const1_rtx
> @findex const2_rtx
> -@findex constm1_rtx
> -There is only one expression object for the integer value zero; it is
> +@findex const64_rtx
> +There is only one expression object for the integer value zero: it is
> the value of the variable @code{const0_rtx}. Likewise, the only
> -expression for integer value one is found in @code{const1_rtx}, the only
> -expression for integer value two is found in @code{const2_rtx}, and the
> -only expression for integer value negative one is found in
> -@code{constm1_rtx}. Any attempt to create an expression of code
> -@code{const_int} and value zero, one, two or negative one will return
> -@code{const0_rtx}, @code{const1_rtx}, @code{const2_rtx} or
> -@code{constm1_rtx} as appropriate.
> +expression for integer value one is found in @code{const1_rtx}, and more
> +generally, the only expression for integer value @var{N} is found in
> +@code{const@var{N}_rtx}, and the only expression for integer value negative
> +@var{N} is found in @code{constm@var{N}_rtx}, both for any @var{N} from 1 up
> +to 64 inclusive. Any attempt to create an expression of code
> +@code{const_int} and value in that range will return @code{const0_rtx},
> +@code{const1_rtx}, and so on, as appropriate.
>
> @findex const_true_rtx
> Similarly, there is only one object for the integer whose value is
> diff --git a/gcc/rtl.h b/gcc/rtl.h
> index 35178b5bfaca..5429b7a3f4ac 100644
> --- a/gcc/rtl.h
> +++ b/gcc/rtl.h
> @@ -3768,10 +3768,135 @@ extern unsigned int split_all_insns_noflow (void);
> #define MAX_SAVED_CONST_INT 64
> extern GTY(()) rtx const_int_rtx[MAX_SAVED_CONST_INT * 2 + 1];
>
> +#define constm64_rtx (const_int_rtx[MAX_SAVED_CONST_INT-64])
> +#define constm63_rtx (const_int_rtx[MAX_SAVED_CONST_INT-63])
> +#define constm62_rtx (const_int_rtx[MAX_SAVED_CONST_INT-62])
> +#define constm61_rtx (const_int_rtx[MAX_SAVED_CONST_INT-61])
> +#define constm60_rtx (const_int_rtx[MAX_SAVED_CONST_INT-60])
> +#define constm59_rtx (const_int_rtx[MAX_SAVED_CONST_INT-59])
> +#define constm58_rtx (const_int_rtx[MAX_SAVED_CONST_INT-58])
> +#define constm57_rtx (const_int_rtx[MAX_SAVED_CONST_INT-57])
> +#define constm56_rtx (const_int_rtx[MAX_SAVED_CONST_INT-56])
> +#define constm55_rtx (const_int_rtx[MAX_SAVED_CONST_INT-55])
> +#define constm54_rtx (const_int_rtx[MAX_SAVED_CONST_INT-54])
> +#define constm53_rtx (const_int_rtx[MAX_SAVED_CONST_INT-53])
> +#define constm52_rtx (const_int_rtx[MAX_SAVED_CONST_INT-52])
> +#define constm51_rtx (const_int_rtx[MAX_SAVED_CONST_INT-51])
> +#define constm50_rtx (const_int_rtx[MAX_SAVED_CONST_INT-50])
> +#define constm49_rtx (const_int_rtx[MAX_SAVED_CONST_INT-49])
> +#define constm48_rtx (const_int_rtx[MAX_SAVED_CONST_INT-48])
> +#define constm47_rtx (const_int_rtx[MAX_SAVED_CONST_INT-47])
> +#define constm46_rtx (const_int_rtx[MAX_SAVED_CONST_INT-46])
> +#define constm45_rtx (const_int_rtx[MAX_SAVED_CONST_INT-45])
> +#define constm44_rtx (const_int_rtx[MAX_SAVED_CONST_INT-44])
> +#define constm43_rtx (const_int_rtx[MAX_SAVED_CONST_INT-43])
> +#define constm42_rtx (const_int_rtx[MAX_SAVED_CONST_INT-42])
> +#define constm41_rtx (const_int_rtx[MAX_SAVED_CONST_INT-41])
> +#define constm40_rtx (const_int_rtx[MAX_SAVED_CONST_INT-40])
> +#define constm39_rtx (const_int_rtx[MAX_SAVED_CONST_INT-39])
> +#define constm38_rtx (const_int_rtx[MAX_SAVED_CONST_INT-38])
> +#define constm37_rtx (const_int_rtx[MAX_SAVED_CONST_INT-37])
> +#define constm36_rtx (const_int_rtx[MAX_SAVED_CONST_INT-36])
> +#define constm35_rtx (const_int_rtx[MAX_SAVED_CONST_INT-35])
> +#define constm34_rtx (const_int_rtx[MAX_SAVED_CONST_INT-34])
> +#define constm33_rtx (const_int_rtx[MAX_SAVED_CONST_INT-33])
> +#define constm32_rtx (const_int_rtx[MAX_SAVED_CONST_INT-32])
> +#define constm31_rtx (const_int_rtx[MAX_SAVED_CONST_INT-31])
> +#define constm30_rtx (const_int_rtx[MAX_SAVED_CONST_INT-30])
> +#define constm29_rtx (const_int_rtx[MAX_SAVED_CONST_INT-29])
> +#define constm28_rtx (const_int_rtx[MAX_SAVED_CONST_INT-28])
> +#define constm27_rtx (const_int_rtx[MAX_SAVED_CONST_INT-27])
> +#define constm26_rtx (const_int_rtx[MAX_SAVED_CONST_INT-26])
> +#define constm25_rtx (const_int_rtx[MAX_SAVED_CONST_INT-25])
> +#define constm24_rtx (const_int_rtx[MAX_SAVED_CONST_INT-24])
> +#define constm23_rtx (const_int_rtx[MAX_SAVED_CONST_INT-23])
> +#define constm22_rtx (const_int_rtx[MAX_SAVED_CONST_INT-22])
> +#define constm21_rtx (const_int_rtx[MAX_SAVED_CONST_INT-21])
> +#define constm20_rtx (const_int_rtx[MAX_SAVED_CONST_INT-20])
> +#define constm19_rtx (const_int_rtx[MAX_SAVED_CONST_INT-19])
> +#define constm18_rtx (const_int_rtx[MAX_SAVED_CONST_INT-18])
> +#define constm17_rtx (const_int_rtx[MAX_SAVED_CONST_INT-17])
> +#define constm16_rtx (const_int_rtx[MAX_SAVED_CONST_INT-16])
> +#define constm15_rtx (const_int_rtx[MAX_SAVED_CONST_INT-15])
> +#define constm14_rtx (const_int_rtx[MAX_SAVED_CONST_INT-14])
> +#define constm13_rtx (const_int_rtx[MAX_SAVED_CONST_INT-13])
> +#define constm12_rtx (const_int_rtx[MAX_SAVED_CONST_INT-12])
> +#define constm11_rtx (const_int_rtx[MAX_SAVED_CONST_INT-11])
> +#define constm10_rtx (const_int_rtx[MAX_SAVED_CONST_INT-10])
> +#define constm9_rtx (const_int_rtx[MAX_SAVED_CONST_INT-9])
> +#define constm8_rtx (const_int_rtx[MAX_SAVED_CONST_INT-8])
> +#define constm7_rtx (const_int_rtx[MAX_SAVED_CONST_INT-7])
> +#define constm6_rtx (const_int_rtx[MAX_SAVED_CONST_INT-6])
> +#define constm5_rtx (const_int_rtx[MAX_SAVED_CONST_INT-5])
> +#define constm4_rtx (const_int_rtx[MAX_SAVED_CONST_INT-4])
> +#define constm3_rtx (const_int_rtx[MAX_SAVED_CONST_INT-3])
> +#define constm2_rtx (const_int_rtx[MAX_SAVED_CONST_INT-2])
> +#define constm1_rtx (const_int_rtx[MAX_SAVED_CONST_INT-1])
> #define const0_rtx (const_int_rtx[MAX_SAVED_CONST_INT])
> #define const1_rtx (const_int_rtx[MAX_SAVED_CONST_INT+1])
> #define const2_rtx (const_int_rtx[MAX_SAVED_CONST_INT+2])
> -#define constm1_rtx (const_int_rtx[MAX_SAVED_CONST_INT-1])
> +#define const3_rtx (const_int_rtx[MAX_SAVED_CONST_INT+3])
> +#define const4_rtx (const_int_rtx[MAX_SAVED_CONST_INT+4])
> +#define const5_rtx (const_int_rtx[MAX_SAVED_CONST_INT+5])
> +#define const6_rtx (const_int_rtx[MAX_SAVED_CONST_INT+6])
> +#define const7_rtx (const_int_rtx[MAX_SAVED_CONST_INT+7])
> +#define const8_rtx (const_int_rtx[MAX_SAVED_CONST_INT+8])
> +#define const9_rtx (const_int_rtx[MAX_SAVED_CONST_INT+9])
> +#define const10_rtx (const_int_rtx[MAX_SAVED_CONST_INT+10])
> +#define const11_rtx (const_int_rtx[MAX_SAVED_CONST_INT+11])
> +#define const12_rtx (const_int_rtx[MAX_SAVED_CONST_INT+12])
> +#define const13_rtx (const_int_rtx[MAX_SAVED_CONST_INT+13])
> +#define const14_rtx (const_int_rtx[MAX_SAVED_CONST_INT+14])
> +#define const15_rtx (const_int_rtx[MAX_SAVED_CONST_INT+15])
> +#define const16_rtx (const_int_rtx[MAX_SAVED_CONST_INT+16])
> +#define const17_rtx (const_int_rtx[MAX_SAVED_CONST_INT+17])
> +#define const18_rtx (const_int_rtx[MAX_SAVED_CONST_INT+18])
> +#define const19_rtx (const_int_rtx[MAX_SAVED_CONST_INT+19])
> +#define const20_rtx (const_int_rtx[MAX_SAVED_CONST_INT+20])
> +#define const21_rtx (const_int_rtx[MAX_SAVED_CONST_INT+21])
> +#define const22_rtx (const_int_rtx[MAX_SAVED_CONST_INT+22])
> +#define const23_rtx (const_int_rtx[MAX_SAVED_CONST_INT+23])
> +#define const24_rtx (const_int_rtx[MAX_SAVED_CONST_INT+24])
> +#define const25_rtx (const_int_rtx[MAX_SAVED_CONST_INT+25])
> +#define const26_rtx (const_int_rtx[MAX_SAVED_CONST_INT+26])
> +#define const27_rtx (const_int_rtx[MAX_SAVED_CONST_INT+27])
> +#define const28_rtx (const_int_rtx[MAX_SAVED_CONST_INT+28])
> +#define const29_rtx (const_int_rtx[MAX_SAVED_CONST_INT+29])
> +#define const30_rtx (const_int_rtx[MAX_SAVED_CONST_INT+30])
> +#define const31_rtx (const_int_rtx[MAX_SAVED_CONST_INT+31])
> +#define const32_rtx (const_int_rtx[MAX_SAVED_CONST_INT+32])
> +#define const33_rtx (const_int_rtx[MAX_SAVED_CONST_INT+33])
> +#define const34_rtx (const_int_rtx[MAX_SAVED_CONST_INT+34])
> +#define const35_rtx (const_int_rtx[MAX_SAVED_CONST_INT+35])
> +#define const36_rtx (const_int_rtx[MAX_SAVED_CONST_INT+36])
> +#define const37_rtx (const_int_rtx[MAX_SAVED_CONST_INT+37])
> +#define const38_rtx (const_int_rtx[MAX_SAVED_CONST_INT+38])
> +#define const39_rtx (const_int_rtx[MAX_SAVED_CONST_INT+39])
> +#define const40_rtx (const_int_rtx[MAX_SAVED_CONST_INT+40])
> +#define const41_rtx (const_int_rtx[MAX_SAVED_CONST_INT+41])
> +#define const42_rtx (const_int_rtx[MAX_SAVED_CONST_INT+42])
> +#define const43_rtx (const_int_rtx[MAX_SAVED_CONST_INT+43])
> +#define const44_rtx (const_int_rtx[MAX_SAVED_CONST_INT+44])
> +#define const45_rtx (const_int_rtx[MAX_SAVED_CONST_INT+45])
> +#define const46_rtx (const_int_rtx[MAX_SAVED_CONST_INT+46])
> +#define const47_rtx (const_int_rtx[MAX_SAVED_CONST_INT+47])
> +#define const48_rtx (const_int_rtx[MAX_SAVED_CONST_INT+48])
> +#define const49_rtx (const_int_rtx[MAX_SAVED_CONST_INT+49])
> +#define const50_rtx (const_int_rtx[MAX_SAVED_CONST_INT+50])
> +#define const51_rtx (const_int_rtx[MAX_SAVED_CONST_INT+51])
> +#define const52_rtx (const_int_rtx[MAX_SAVED_CONST_INT+52])
> +#define const53_rtx (const_int_rtx[MAX_SAVED_CONST_INT+53])
> +#define const54_rtx (const_int_rtx[MAX_SAVED_CONST_INT+54])
> +#define const55_rtx (const_int_rtx[MAX_SAVED_CONST_INT+55])
> +#define const56_rtx (const_int_rtx[MAX_SAVED_CONST_INT+56])
> +#define const57_rtx (const_int_rtx[MAX_SAVED_CONST_INT+57])
> +#define const58_rtx (const_int_rtx[MAX_SAVED_CONST_INT+58])
> +#define const59_rtx (const_int_rtx[MAX_SAVED_CONST_INT+59])
> +#define const60_rtx (const_int_rtx[MAX_SAVED_CONST_INT+60])
> +#define const61_rtx (const_int_rtx[MAX_SAVED_CONST_INT+61])
> +#define const62_rtx (const_int_rtx[MAX_SAVED_CONST_INT+62])
> +#define const63_rtx (const_int_rtx[MAX_SAVED_CONST_INT+63])
> +#define const64_rtx (const_int_rtx[MAX_SAVED_CONST_INT+64])
> extern GTY(()) rtx const_true_rtx;
>
> extern GTY(()) rtx const_tiny_rtx[4][(int) MAX_MACHINE_MODE];
