c++: Fix up handling of register ... asm ("...") vars in templates [PR33661, PR98847]

As the testcase shows, for vars appearing in templates, we don't attach
the asm spec string to the pattern decls, nor pass it back to cp_finish_decl
during instantiation.

The following patch does that.

2021-01-28  Jakub Jelinek  <jakub@redhat.com>

	PR c++/33661
	PR c++/98847
	* decl.c (cp_finish_decl): For register vars with asmspec in templates
	call set_user_assembler_name and set DECL_HARD_REGISTER.
	* pt.c (tsubst_expr): When instantiating DECL_HARD_REGISTER vars,
	pass asmspec_tree to cp_finish_decl.

	* g++.target/i386/pr98847.C: New test.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 1a114a2..3b9875e 100644 (file)
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7840,6 +7840,12 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
          retrofit_lang_decl (decl);
          SET_DECL_DEPENDENT_INIT_P (decl, true);
        }
+
+      if (VAR_P (decl) && DECL_REGISTER (decl) && asmspec)
+       {
+         set_user_assembler_name (decl, asmspec);
+         DECL_HARD_REGISTER (decl) = 1;
+       }
       return;
     }
 

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 8f05ce2..9089afb 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18238,6 +18238,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
                    bool const_init = false;
                    unsigned int cnt = 0;
                    tree first = NULL_TREE, ndecl = error_mark_node;
+                   tree asmspec_tree = NULL_TREE;
                    maybe_push_decl (decl);
 
                    if (VAR_P (decl)
@@ -18261,7 +18262,18 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
                       now.  */
                    predeclare_vla (decl);
 
-                   cp_finish_decl (decl, init, const_init, NULL_TREE, 0);
+                   if (VAR_P (decl) && DECL_HARD_REGISTER (pattern_decl))
+                     {
+                       tree id = DECL_ASSEMBLER_NAME (pattern_decl);
+                       const char *asmspec = IDENTIFIER_POINTER (id);
+                       gcc_assert (asmspec[0] == '*');
+                       asmspec_tree
+                         = build_string (IDENTIFIER_LENGTH (id) - 1,
+                                         asmspec + 1);
+                       TREE_TYPE (asmspec_tree) = char_array_type_node;
+                     }
+
+                   cp_finish_decl (decl, init, const_init, asmspec_tree, 0);
 
                    if (ndecl != error_mark_node)
                      cp_finish_decomp (ndecl, first, cnt);

diff --git a/gcc/testsuite/g++.target/i386/pr98847.C b/gcc/testsuite/g++.target/i386/pr98847.C
new file mode 100644 (file)
index 0000000..0a72ccc
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr98847.C
@@ -0,0 +1,20 @@
+// PR c++/98847
+// { dg-do run }
+// { dg-options "-O2 -masm=att" }
+
+template <int N>
+int
+foo ()
+{
+  register int edx asm ("edx");
+  asm ("movl $1234, %%edx" : "=r" (edx));
+  return edx;
+}
+
+int
+main ()
+{
+  if (foo<0> () != 1234)
+    __builtin_abort ();
+  return 0;
+}