re PR fortran/23906 (inappropriate branch condition in function…

re PR fortran/23906 (inappropriate branch condition in function "transform_sections" in "dependency.c")

2005-09-16  Paul Brook  <paul@codesourcery.com>

	PR fortran/23906
fortran/
	* dependency.c (transform_sections): Divide by correct value.
	Elaborate comment.
testsuite/
	* gfortran.dg/dependency_1.f90: New test.

From-SVN: r104339

gcc/fortran/ChangeLog

+2005-09-16  Paul Brook  <paul@codesourcery.com>
+
+	PR fortran/23906
+	* dependency.c (transform_sections): Divide by correct value.
+	Elaborate comment.
+
 2005-09-14  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/21875 Internal Unit Array I/O, NIST

gcc/fortran/dependency.c

@@ -392,7 +392,7 @@ get_deps (mpz_t x1, mpz_t x2, mpz_t y)
 }
 
 
-/* Transforms a sections l and r such that 
+/* Perform the same linear transformation on sections l and r such that 
    (l_start:l_end:l_stride) -> (0:no_of_elements)
    (r_start:r_end:r_stride) -> (X1:X2)
    Where r_end is implicit as both sections must have the same number of
@@ -434,7 +434,7 @@ transform_sections (mpz_t X1, mpz_t X2, mpz_t no_of_elements,
     mpz_mul (X2, no_of_elements, r_stride->value.integer);
 
   if (l_stride != NULL)
-    mpz_cdiv_q (X2, X2, r_stride->value.integer);
+    mpz_cdiv_q (X2, X2, l_stride->value.integer);
   mpz_add (X2, X2, X1);
 
   return 0;

gcc/testsuite/ChangeLog

+2005-09-16  Paul Brook  <paul@codesourcery.com>
+
+	PR fortran/23906
+	* gfortran.dg/dependency_1.f90: New test.
+
 2005-09-15  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/23896

gcc/testsuite/gfortran.dg/dependency_1.f90

+! { dg-do compile }
+! PR23906
+! Dependency analysis was using the stride from the wrong expression and
+! segfaulting
+subroutine foo(a)
+  real, dimension(:) :: a
+
+  a(1:3:2) = a(1:2) 
+  a(1:2) = a(1:3:2) 
+end subroutine
+