Fix SSA inconsistencies with invalid asm reg names (PR67639)

	PR middle-end/67639
	* varasm.c (make_decl_rtl): Mark invalid register vars as
	DECL_EXTERNAL.

testsuite/
	PR middle-end/67639
	* c-c++-common/pr67639.c: New test.

From-SVN: r232125

gcc/ChangeLog

 2015-12-15  Bernd Schmidt  <bschmidt@redhat.com>
 
+	PR middle-end/67639
+	* varasm.c (make_decl_rtl): Mark invalid register vars as
+	DECL_EXTERNAL.
+
 	PR rtl-optimization/66206
 	* bt-load.c (find_btr_use): Change first arg to be a pointer to an rtx.
 	All callers changed.

gcc/testsuite/ChangeLog

+2015-12-15  Bernd Schmidt  <bschmidt@redhat.com>
+
+	PR middle-end/67639
+	* c-c++-common/pr67639.c: New test.
+
 2016-01-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/69141

gcc/testsuite/c-c++-common/pr67639.c

+/* { dg-do compile } */
+void
+foo (int p)
+{
+  int t; 
+  register long x asm ("rhubarb") = p; /* { dg-error "register name" } */
+  __asm ("" : "=r" (t), "=r" (t), "=r" (t), "=r" (x) : "0" (x));
+}

gcc/varasm.c

@@ -1420,6 +1420,9 @@ make_decl_rtl (tree decl)
 	 specifications.  */
       SET_DECL_ASSEMBLER_NAME (decl, NULL_TREE);
       DECL_HARD_REGISTER (decl) = 0;
+      /* Also avoid SSA inconsistencies by pretending this is an external
+	 decl now.  */
+      DECL_EXTERNAL (decl) = 1;
       return;
     }
   /* Now handle ordinary static variables and functions (in memory).