gimple-fold: Remove incorrect folding of debug stmts [PR103691]

For ADDR_EXPR gimple_debug_bind_get_value fold_stmt_1 uses
maybe_canonicalize_mem_ref_addr earlier and I think that should
resolve the concerns raised in PR52329.  But folding ADDR_EXPR
operand using maybe_fold_reference and then taking address of that
looks like an invalid transformation, it can transform
  # DEBUG D.4293 => &a[0]
into
  # DEBUG D.4293 => &2.0e+0
etc., all we want to allow are the lhs folding of the operand which
maybe_fold_reference no longer does since r12-21-g0bf8cd9d5e8ac.

2022-01-05  Jakub Jelinek  <jakub@redhat.com>

	PR fortran/103691
	* gimple-fold.c (fold_stmt_1): Don't call maybe_fold_reference
	for DEBUG stmts with ADDR_EXPR gimple_debug_bind_get_value,
	it can do unwanted rhs folding like &a[0] into &2.0 etc.

	* gfortran.dg/pr103691.f90: New test.

diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 80e7d89..77c551a 100644 (file)
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -6283,8 +6283,7 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
       if (gimple_debug_bind_p (stmt))
        {
          tree val = gimple_debug_bind_get_value (stmt);
-         if (val
-             && REFERENCE_CLASS_P (val))
+         if (val && REFERENCE_CLASS_P (val))
            {
              tree tem = maybe_fold_reference (val);
              if (tem)
@@ -6293,18 +6292,6 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
                  changed = true;
                }
            }
-         else if (val
-                  && TREE_CODE (val) == ADDR_EXPR)
-           {
-             tree ref = TREE_OPERAND (val, 0);
-             tree tem = maybe_fold_reference (ref);
-             if (tem)
-               {
-                 tem = build_fold_addr_expr_with_type (tem, TREE_TYPE (val));
-                 gimple_debug_bind_set_value (stmt, tem);
-                 changed = true;
-               }
-           }
        }
       break;
 

diff --git a/gcc/testsuite/gfortran.dg/pr103691.f90 b/gcc/testsuite/gfortran.dg/pr103691.f90
new file mode 100644 (file)
index 0000000..f1f551e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr103691.f90
@@ -0,0 +1,9 @@
+! PR fortran/103691
+! { dg-do compile }
+! { dg-options "-O2 -g" }
+
+program pr103691
+  real, parameter :: a(0) = 2.0
+  real, allocatable :: b(:)
+  allocate (b, mold=a)
+end