diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/fortran/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/fortran/trans-expr.c | 35 |
2 files changed, 34 insertions, 6 deletions
diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog index 6309b5a..587a010 100644 --- a/gcc/fortran/ChangeLog +++ b/gcc/fortran/ChangeLog @@ -1,5 +1,10 @@ 2012-08-14 Mikael Morin <mikael@gcc.gnu.org> + * trans-expr.c (gfc_trans_scalar_assign): Rename argument, + extend comment. + +2012-08-14 Mikael Morin <mikael@gcc.gnu.org> + * gfortran.h (gfc_get_proc_ptr_comp): New prototype. (gfc_is_proc_ptr_comp): Update prototype. * expr.c (gfc_get_proc_ptr_comp): New function based on the old diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c index 12a75d0..53fdf45 100644 --- a/gcc/fortran/trans-expr.c +++ b/gcc/fortran/trans-expr.c @@ -6307,11 +6307,34 @@ gfc_conv_string_parameter (gfc_se * se) /* Generate code for assignment of scalar variables. Includes character strings and derived types with allocatable components. - If you know that the LHS has no allocations, set dealloc to false. */ + If you know that the LHS has no allocations, set dealloc to false. + + DEEP_COPY has no effect if the typespec TS is not a derived type with + allocatable components. Otherwise, if it is set, an explicit copy of each + allocatable component is made. This is necessary as a simple copy of the + whole object would copy array descriptors as is, so that the lhs's + allocatable components would point to the rhs's after the assignment. + Typically, setting DEEP_COPY is necessary if the rhs is a variable, and not + necessary if the rhs is a non-pointer function, as the allocatable components + are not accessible by other means than the function's result after the + function has returned. It is even more subtle when temporaries are involved, + as the two following examples show: + 1. When we evaluate an array constructor, a temporary is created. Thus + there is theoretically no alias possible. However, no deep copy is + made for this temporary, so that if the constructor is made of one or + more variable with allocatable components, those components still point + to the variable's: DEEP_COPY should be set for the assignment from the + temporary to the lhs in that case. + 2. When assigning a scalar to an array, we evaluate the scalar value out + of the loop, store it into a temporary variable, and assign from that. + In that case, deep copying when assigning to the temporary would be a + waste of resources; however deep copies should happen when assigning from + the temporary to each array element: again DEEP_COPY should be set for + the assignment from the temporary to the lhs. */ tree gfc_trans_scalar_assign (gfc_se * lse, gfc_se * rse, gfc_typespec ts, - bool l_is_temp, bool r_is_var, bool dealloc) + bool l_is_temp, bool deep_copy, bool dealloc) { stmtblock_t block; tree tmp; @@ -6345,9 +6368,9 @@ gfc_trans_scalar_assign (gfc_se * lse, gfc_se * rse, gfc_typespec ts, else if (ts.type == BT_DERIVED && ts.u.derived->attr.alloc_comp) { cond = NULL_TREE; - + /* Are the rhs and the lhs the same? */ - if (r_is_var) + if (deep_copy) { cond = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node, gfc_build_addr_expr (NULL_TREE, lse->expr), @@ -6363,7 +6386,7 @@ gfc_trans_scalar_assign (gfc_se * lse, gfc_se * rse, gfc_typespec ts, { tmp = gfc_evaluate_now (lse->expr, &lse->pre); tmp = gfc_deallocate_alloc_comp (ts.u.derived, tmp, 0); - if (r_is_var) + if (deep_copy) tmp = build3_v (COND_EXPR, cond, build_empty_stmt (input_location), tmp); gfc_add_expr_to_block (&lse->post, tmp); @@ -6377,7 +6400,7 @@ gfc_trans_scalar_assign (gfc_se * lse, gfc_se * rse, gfc_typespec ts, /* Do a deep copy if the rhs is a variable, if it is not the same as the lhs. */ - if (r_is_var) + if (deep_copy) { tmp = gfc_copy_alloc_comp (ts.u.derived, rse->expr, lse->expr, 0); tmp = build3_v (COND_EXPR, cond, build_empty_stmt (input_location), |