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 <tkoe...@gcc.gnu.org>
PR fortran/57071
* frontend-passes (optimize_power): New function.
(optimize_op): Use it.
2013-04-28 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/57071
* gfortran.dg/power_3.f90: New test.
* gfortran.dg/power_4.f90: New test.
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;
}
! { dg-do run }
! { dg-options "-ffrontend-optimize -fdump-tree-original" }
! PR 57071 - Check that (-1)**k is transformed into 1-2*iand(k,1).
program main
implicit none
integer, parameter :: n = 3
integer(kind=8), dimension(-n:n) :: a, b
integer, dimension(-n:n) :: c, d, e
integer :: m
integer :: i, v
integer (kind=2) :: i2
m = n
v = -1
! Test in scalar expressions
do i=-n,n
if (v**i /= (-1)**i) call abort
end do
! Test in array constructors
a(-m:m) = [ ((-1)**i, i= -m, m) ]
b(-m:m) = [ ( v**i, i= -m, m) ]
if (any(a .ne. b)) call abort
! Test in array expressions
c = [ ( i, i = -n , n ) ]
d = (-1)**c
e = v**c
if (any(d .ne. e)) call abort
! Test in different kind expressions
do i2=-n,n
if (v**i2 /= (-1)**i2) call abort
end do
end program main
! { dg-final { scan-tree-dump-times "_gfortran_pow_i4_i4" 4 "original" } }
! { dg-final { cleanup-tree-dump "original" } }
! { dg-do run }
! { dg-options "-ffrontend-optimize -fdump-tree-original" }
! PR 57071 - Check that 2**k is transformed into ishift(1,k).
program main
implicit none
integer :: i,m,v
integer, parameter :: n=30
integer, dimension(-n:n) :: a,b,c,d,e
m = n
v = 2
! Test scalar expressions.
do i=-n,n
if (2**i /= v**i) call abort
end do
! Test array constructors
b = [(2**i,i=-m,m)]
c = [(v**i,i=-m,m)]
if (any(b /= c)) call abort
! Test array expressions
a = [(i,i=-m,m)]
d = 2**a
e = v**a
if (any(d /= e)) call abort
end program main
! { dg-final { scan-tree-dump-times "_gfortran_pow_i4_i4" 3 "original" } }
! { dg-final { cleanup-tree-dump "original" } }
