re PR fortran/57071 (Optimize (-1)**k to 1 - 2 * mod(K, 2))

2013-04-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/57071
	* frontend-passes.c (optimize_power):  Simplify
	1**k to 1.

2013-04-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/57071
	* gfortran.dg/power_5.f90:  New test.

From-SVN: r198476

gcc/fortran/ChangeLog

+2013-04-30  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/57071
+	* frontend-passes.c (optimize_power):  Simplify
+	1**k to 1.
+
 2013-04-28  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/57114

gcc/fortran/frontend-passes.c

@@ -1148,6 +1148,24 @@ optimize_power (gfc_expr *e)
       *e = *ishft;
       return true;
     }
+
+  else if (mpz_cmp_si (op1->value.integer, 1L) == 0)
+    {
+      op2 = e->value.op.op2;
+      if (op2 == NULL)
+	return false;
+
+      gfc_free_expr (op1);
+      gfc_free_expr (op2);
+
+      e->expr_type = EXPR_CONSTANT;
+      e->value.op.op1 = NULL;
+      e->value.op.op2 = NULL;
+      mpz_init_set_si (e->value.integer, 1);
+      /* Typespec cand location are still OK.  */
+      return true;
+    }
+
   return false;
 }
 

gcc/testsuite/ChangeLog

+2013-04-30  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/57071
+	* gfortran.dg/power_5.f90:  New test.
+
 2013-04-30  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/57122

gcc/testsuite/gfortran.dg/power_5.f90

+! { dg-do run }
+! { dg-options "-ffrontend-optimize -fdump-tree-original" }
+! PR 57071 - Check that 1**k is transformed into 1
+program main
+  implicit none
+  integer, parameter :: n = 3
+  integer(kind=8), dimension(-n:n) :: a
+  integer, dimension(-n:n) :: c, d
+  integer :: m
+  integer :: i, v
+  integer (kind=2) :: i2
+
+  v = 1
+  m = n
+  ! Test in scalar expressions
+  do i=-n,n
+     if (v /= 1**i) call abort
+  end do
+
+  ! Test in array constructors
+  a(-m:m) = [ (1**i, i= -m, m) ]
+  if (any(a .ne. v)) call abort
+
+  ! Test in array expressions
+  c = [ ( i, i = -n , n ) ]
+  d = 1**c
+  if (any(d .ne. v)) call abort
+
+  ! Test in different kind expressions
+  do i2=-n,n
+     if (v /= 1**i2) call abort
+  end do
+
+end program main
+! { dg-final { scan-tree-dump-times "_gfortran_pow_i4_i4" 0 "original" } }
+! { dg-final { cleanup-tree-dump "original" } }