| Message ID | 517CDE9C.2020301@netcologne.de |
|---|---|
| State | New |
| Headers | show |
Am 28.04.2013 10:32, schrieb Thomas Koenig: > the attached patch does some optimization on > power using ishft and iand, as discussed in the PR. > > I have left out handling real numbers, that should be left > to the middle-end (PR 57073). > > Regression-tested. OK for trunk? OK - thanks for the patch. I wonder whether one should also handle: 1**k == 1 That should only happen (in-real-world code) due to simplifying other expressions but it is simple to implement. (0**k is also possible, but it gets more complicated: 0 for k > 0, 1 for k == 0 and invalid for k < 0 [which one might ignore]. As this is really special, one can also leave the library call.) Tobias > 2013-04-28 Thomas Koenig <tkoenig@gcc.gnu.org> > > PR fortran/57071 > * frontend-passes (optimize_power): New function. > (optimize_op): Use it. > > 2013-04-28 Thomas Koenig <tkoenig@gcc.gnu.org> > > PR fortran/57071 > * gfortran.dg/power_3.f90: New test. > * gfortran.dg/power_4.f90: New test.
On Sun, Apr 28, 2013 at 10:32:28AM +0200, Thomas Koenig wrote: > Hello world, > > the attached patch does some optimization on > power using ishft and iand, as discussed in the PR. > > I have left out handling real numbers, that should be left > to the middle-end (PR 57073). > > Regression-tested. OK for trunk? > % cat foo.f90 function foo(k) integer k integer foo foo = (1)**k end function foo % cat foo.f90.003t.original foo (integer(kind=4) & restrict k) { integer(kind=4) __result_foo; __result_foo = _gfortran_pow_i4_i4 (1, *k); return __result_foo; } % cat foo.f90.143t.optimized ;; Function foo (foo_) foo (integer(kind=4) & restrict k) { integer(kind=4) __result_foo.0; integer(kind=4) D.1479; <bb 2>: D.1479_2 = *k_1(D); __result_foo.0_3 = _gfortran_pow_i4_i4 (1, D.1479_2); [tail call] return __result_foo.0_3; } % nm foo.o U _gfortran_pow_i4_i4 00000000 T foo_ :-)
Am 28.04.2013 12:10, schrieb Tobias Burnus: > OK - thanks for the patch. > > I wonder whether one should also handle: > 1**k == 1 Committed, thanks for the review! I will do 1**k as a followup patch which should be quite obvious :-) Regarding PR 57073, the real case - I have never worked with GIMPLE, so I have no real idea how to start this. Any volunteers? Or should we handle this in the Fortran front end after all? Thomas
Thomas Koenig wrote: > Regarding PR 57073, the real case - I have never worked with > GIMPLE, so I have no real idea how to start this. > > Any volunteers? Or should we handle this in the Fortran front > end after all? I think one should do it in the middle end. Actually, it shouldn't be that difficult. The starting point is gcc/builtins.c's fold_builtin_powi - all ingredients are there; (1.0)**k, x**0, x**1 and x**(-1) are already handled. Thus, only (-1)**k is missing. For "= (a)?(b):(c)" one uses "fold_build3_loc (loc, COND_EXPR, ..." and to check whether a real argument is -1, you can use "real_minus_onep". How about writing your first middle end patch? Tobias
Index: frontend-passes.c =================================================================== --- frontend-passes.c (Revision 198340) +++ frontend-passes.c (Arbeitskopie) @@ -1091,7 +1091,66 @@ combine_array_constructor (gfc_expr *e) return true; } +/* Change (-1)**k into 1-ishift(iand(k,1),1) and + 2**k into ishift(1,k) */ +static bool +optimize_power (gfc_expr *e) +{ + gfc_expr *op1, *op2; + gfc_expr *iand, *ishft; + + if (e->ts.type != BT_INTEGER) + return false; + + op1 = e->value.op.op1; + + if (op1 == NULL || op1->expr_type != EXPR_CONSTANT) + return false; + + if (mpz_cmp_si (op1->value.integer, -1L) == 0) + { + gfc_free_expr (op1); + + op2 = e->value.op.op2; + + if (op2 == NULL) + return false; + + iand = gfc_build_intrinsic_call (current_ns, GFC_ISYM_IAND, + "_internal_iand", e->where, 2, op2, + gfc_get_int_expr (e->ts.kind, + &e->where, 1)); + + ishft = gfc_build_intrinsic_call (current_ns, GFC_ISYM_ISHFT, + "_internal_ishft", e->where, 2, iand, + gfc_get_int_expr (e->ts.kind, + &e->where, 1)); + + e->value.op.op = INTRINSIC_MINUS; + e->value.op.op1 = gfc_get_int_expr (e->ts.kind, &e->where, 1); + e->value.op.op2 = ishft; + return true; + } + else if (mpz_cmp_si (op1->value.integer, 2L) == 0) + { + gfc_free_expr (op1); + + op2 = e->value.op.op2; + if (op2 == NULL) + return false; + + ishft = gfc_build_intrinsic_call (current_ns, GFC_ISYM_ISHFT, + "_internal_ishft", e->where, 2, + gfc_get_int_expr (e->ts.kind, + &e->where, 1), + op2); + *e = *ishft; + return true; + } + return false; +} + /* Recursive optimization of operators. */ static bool @@ -1152,6 +1211,10 @@ optimize_op (gfc_expr *e) case INTRINSIC_DIVIDE: return combine_array_constructor (e) || changed; + case INTRINSIC_POWER: + return optimize_power (e); + break; + default: break; }
Hello world, the attached patch does some optimization on power using ishft and iand, as discussed in the PR. I have left out handling real numbers, that should be left to the middle-end (PR 57073). Regression-tested. OK for trunk? Thomas 2013-04-28 Thomas Koenig <tkoenig@gcc.gnu.org> PR fortran/57071 * frontend-passes (optimize_power): New function. (optimize_op): Use it. 2013-04-28 Thomas Koenig <tkoenig@gcc.gnu.org> PR fortran/57071 * gfortran.dg/power_3.f90: New test. * gfortran.dg/power_4.f90: New test.