This avoids a regression on deferred_character_23.f90 later in the
patch series when array references are rewritten to use pointer
arithmetic.
The problem is a SAVE_EXPR tree as TYPE_SIZE_UNIT of one array element
type, which is used by the pointer arithmetic expressions. As these
expressions appear in both branches of an if-then-else block, the tree
is lowered to a variable in one of the branches but it’s used in both
branches, which is invalid middle-end code.
This change pre-evaluates the array references or pointer arithmetics
to variables before the if-then-else block, so that the SAVE_EXPR are
expanded to variables in the parent scope of the if-then-else block,
and expressions referencing the variables remain valid in both
branches.
PR fortran/102043
gcc/fortran/ChangeLog:
* trans-expr.cc: Pre-evaluate src and dest to variables
before using them.
gcc/testsuite/ChangeLog:
* gfortran.dg/dependency_49.f90: Update variable occurence
count.
---
gcc/fortran/trans-expr.cc | 7 +++++++
gcc/testsuite/gfortran.dg/dependency_49.f90 | 3 ++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 06713f24f95..3962b6848ce 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -8093,6 +8093,13 @@ gfc_trans_string_copy (stmtblock_t * block, tree
dlength, tree dest,
cond2 = fold_build2_loc (input_location, LT_EXPR, logical_type_node, slen,
dlen);
+ /* Pre-evaluate pointers unless one of the IF arms will be optimized away.
*/
+ if (!CONSTANT_CLASS_P (cond2))
+ {
+ dest = gfc_evaluate_now (dest, block);
+ src = gfc_evaluate_now (src, block);
+ }
+
/* Copy and pad with spaces. */
tmp3 = build_call_expr_loc (input_location,
builtin_decl_explicit (BUILT_IN_MEMMOVE),
diff --git a/gcc/testsuite/gfortran.dg/dependency_49.f90
b/gcc/testsuite/gfortran.dg/dependency_49.f90
index 73d517e8f76..9638f65c069 100644
--- a/gcc/testsuite/gfortran.dg/dependency_49.f90
+++ b/gcc/testsuite/gfortran.dg/dependency_49.f90
@@ -11,4 +11,5 @@ program main
a%x = a%x(2:3)
print *,a%x
end program main
-! { dg-final { scan-tree-dump-times "__var_1" 4 "original" } }
+! The temporary var appears three times: declaration, copy-in and copy-out
+! { dg-final { scan-tree-dump-times "__var_1" 3 "original" } }
--
2.35.1
