| Message ID | 20201127222516.44915-1-luc.vanoostenryck@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | 'bits translation' simplification | expand |
On Fri, Nov 27, 2020 at 2:28 PM Luc Van Oostenryck <luc.vanoostenryck@gmail.com> wrote: > > With a better if-conversion mechanism it also allows to optimize > int translate_bits(int x) > { > int y = 0; > if (x & 4) > y |= 16; > if (x & 8) > y |= 32; > return y; > } > > into this nice: > translate_bits: > and.32 %r2 <- %arg1, $12 > shl.32 %r5 <- %r2, $2 > ret.32 %r5 > > when applied on top of the previous 'factorization' series. Heh. Very nice. Thanks, Linus
This series allows the simplification of expressions like: if (val1 & 4) val2 |= 8; into val2 |= (val1 & 4) << 1; With a better if-conversion mechanism it also allows to optimize int translate_bits(int x) { int y = 0; if (x & 4) y |= 16; if (x & 8) y |= 32; return y; } into this nice: translate_bits: and.32 %r2 <- %arg1, $12 shl.32 %r5 <- %r2, $2 ret.32 %r5 when applied on top of the previous 'factorization' series. This series is available for review and testing at: git://git.kernel.org/pub/scm/devel/sparse/sparse-dev.git bit-trans Luc Van Oostenryck (6): add testscases for 'bits translation' optimization factorize SEL(x, OP(y,z), y) into OP(SEL(x, z, 0), y) add helper is_power_of_2() add helper is_pow2() add log base 2 function: log2_exact() convert SEL(x & BIT1, BIT2, 0) into SHIFT(x & BIT1, S) bits.h | 12 ++++++ simplify.c | 64 +++++++++++++++++++++++++++++ validation/optim/fact-select01.c | 25 +++++++++++ validation/optim/select-and-shift.c | 17 ++++++++ 4 files changed, 118 insertions(+) create mode 100644 validation/optim/fact-select01.c create mode 100644 validation/optim/select-and-shift.c