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

[Jason Merrill via Gcc-patches]

On 1/28/21 3:52 AM, Jakub Jelinek wrote:

Hi!

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.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

2021-01-27  Jakub Jelinek  <ja...@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.

--- gcc/cp/decl.c.jj    2021-01-07 22:54:34.000000000 +0100
+++ gcc/cp/decl.c       2021-01-27 10:48:14.399582310 +0100
@@ -7840,6 +7840,12 @@ cp_finish_decl (tree decl, tree init, bo
          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;
      }

--- gcc/cp/pt.c.jj 2021-01-22 10:07:53.643466723 +0100

+++ gcc/cp/pt.c 2021-01-27 10:59:04.109126313 +0100
@@ -18227,6 +18227,7 @@ tsubst_expr (tree t, tree args, tsubst_f
                    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)

@@ -18250,7 +18251,18 @@ tsubst_expr (tree t, tree args, tsubst_f
                       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);
--- gcc/testsuite/g++.target/i386/pr98847.C.jj  2021-01-27 11:01:55.312161637 
+0100
+++ gcc/testsuite/g++.target/i386/pr98847.C     2021-01-27 11:00:26.601179659 
+0100
@@ -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;
+}

        Jakub