| Message ID | 20241018111806.4026759-3-richard.sandiford@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add more folds related to exact division | expand |
On Fri, 18 Oct 2024, Richard Sandiford wrote: > There are a limited number of existing rules that benefit from > knowing that a division is exact. Later patches will add more. OK. Thanks, Richard. > gcc/ > * match.pd: Simplify X / (1 << C) to X /[ex] (1 << C) if the > low C bits of X are clear > > gcc/testsuite/ > * gcc.dg/tree-ssa/cmpexactdiv-6.c: New test. > --- > gcc/match.pd | 9 ++++++ > gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c | 29 +++++++++++++++++++ > 2 files changed, 38 insertions(+) > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c > > diff --git a/gcc/match.pd b/gcc/match.pd > index 4aea028a866..b952225b08c 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -5431,6 +5431,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > TYPE_PRECISION (type)), 0)) > (convert @0))) > > +#if GIMPLE > +/* X / (1 << C) -> X /[ex] (1 << C) if the low C bits of X are clear. */ > +(simplify > + (trunc_div (with_possible_nonzero_bits2 @0) integer_pow2p@1) > + (if (INTEGRAL_TYPE_P (type) > + && !TYPE_UNSIGNED (type) > + && wi::multiple_of_p (get_nonzero_bits (@0), wi::to_wide (@1), SIGNED)) > + (exact_div @0 @1))) > +#endif > > /* (X /[ex] A) * A -> X. */ > (simplify > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c b/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c > new file mode 100644 > index 00000000000..82d517b05ab > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c > @@ -0,0 +1,29 @@ > +/* { dg-options "-O2 -fdump-tree-optimized-raw" } */ > + > +typedef __INTPTR_TYPE__ intptr_t; > + > +int > +f1 (int x, int y) > +{ > + if ((x & 1) || (y & 1)) > + __builtin_unreachable (); > + x /= 2; > + y /= 2; > + return x < y; > +} > + > +int > +f2 (void *ptr1, void *ptr2, void *ptr3) > +{ > + ptr1 = __builtin_assume_aligned (ptr1, 4); > + ptr2 = __builtin_assume_aligned (ptr2, 4); > + ptr3 = __builtin_assume_aligned (ptr3, 4); > + intptr_t diff1 = (intptr_t) ptr1 - (intptr_t) ptr2; > + intptr_t diff2 = (intptr_t) ptr1 - (intptr_t) ptr3; > + diff1 /= 2; > + diff2 /= 2; > + return diff1 < diff2; > +} > + > +/* { dg-final { scan-tree-dump-not {<[a-z]*_div_expr,} "optimized" } } */ > +/* { dg-final { scan-tree-dump-not {<rshift_expr,} "optimized" } } */ >
diff --git a/gcc/match.pd b/gcc/match.pd index 4aea028a866..b952225b08c 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -5431,6 +5431,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) TYPE_PRECISION (type)), 0)) (convert @0))) +#if GIMPLE +/* X / (1 << C) -> X /[ex] (1 << C) if the low C bits of X are clear. */ +(simplify + (trunc_div (with_possible_nonzero_bits2 @0) integer_pow2p@1) + (if (INTEGRAL_TYPE_P (type) + && !TYPE_UNSIGNED (type) + && wi::multiple_of_p (get_nonzero_bits (@0), wi::to_wide (@1), SIGNED)) + (exact_div @0 @1))) +#endif /* (X /[ex] A) * A -> X. */ (simplify diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c b/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c new file mode 100644 index 00000000000..82d517b05ab --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/cmpexactdiv-6.c @@ -0,0 +1,29 @@ +/* { dg-options "-O2 -fdump-tree-optimized-raw" } */ + +typedef __INTPTR_TYPE__ intptr_t; + +int +f1 (int x, int y) +{ + if ((x & 1) || (y & 1)) + __builtin_unreachable (); + x /= 2; + y /= 2; + return x < y; +} + +int +f2 (void *ptr1, void *ptr2, void *ptr3) +{ + ptr1 = __builtin_assume_aligned (ptr1, 4); + ptr2 = __builtin_assume_aligned (ptr2, 4); + ptr3 = __builtin_assume_aligned (ptr3, 4); + intptr_t diff1 = (intptr_t) ptr1 - (intptr_t) ptr2; + intptr_t diff2 = (intptr_t) ptr1 - (intptr_t) ptr3; + diff1 /= 2; + diff2 /= 2; + return diff1 < diff2; +} + +/* { dg-final { scan-tree-dump-not {<[a-z]*_div_expr,} "optimized" } } */ +/* { dg-final { scan-tree-dump-not {<rshift_expr,} "optimized" } } */