Re: [PATCH] Fix free_lang_data on asm stmts (PR lto/91572)

[Richard Biener <rguenther@suse.de>]

On August 31, 2019 8:30:03 AM GMT+02:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>The following testcase ICEs, because on the inline asm LTO streaming
>streams
>the constraint strings ("g" in this case), including their type, but
>the
>fld type discovery doesn't see that type and so we end up streaming
>const
>char type turned into its own main variant.
>
>The strings for asm are in TREE_PURPOSE of the TREE_LIST args.
>walk_tree doesn't walk TREE_PURPOSE though.  Tried to change that, but
>it
>breaks way too much, tried to walk TREE_PURPOSE of TREE_LIST just for
>the
>fld walking (find_decls_types_r), but that doesn't work either, most of
>the
>TREE_PURPOSE we do not want to walk, usually it contains C++ default
>arguments which fld clears.  So, this directed patch walks the
>TREE_PURPOSE
>solely for the asm stmt arguments.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok, but I wonder if we can stream the constraint strings in a simpler way - surely the type doesn't really matter?
Why are they not identifier nodes? 

Richard. 

>2019-08-31  Jakub Jelinek  <jakub@redhat.com>
>
>	PR lto/91572
>	* tree.c (find_decls_types_in_node): Also walk TREE_PURPOSE of
>	GIMPLE_ASM TREE_LIST operands.
>
>	* g++.dg/lto/pr91572_0.C: New test.
>
>--- gcc/tree.c.jj	2019-08-29 10:22:06.337702323 +0200
>+++ gcc/tree.c	2019-08-29 11:07:16.120107950 +0200
>@@ -6142,6 +6142,13 @@ find_decls_types_in_node (struct cgraph_
> 	    {
> 	      tree arg = gimple_op (stmt, i);
> 	      find_decls_types (arg, fld);
>+	      /* find_decls_types doesn't walk TREE_PURPOSE of TREE_LISTs,
>+		 which we need for asm stmts.  */
>+	      if (arg
>+		  && TREE_CODE (arg) == TREE_LIST
>+		  && TREE_PURPOSE (arg)
>+		  && gimple_code (stmt) == GIMPLE_ASM)
>+		find_decls_types (TREE_PURPOSE (arg), fld);
> 	    }
> 	}
>     }
>--- gcc/testsuite/g++.dg/lto/pr91572_0.C.jj	2019-08-28
>18:13:47.718349087 +0200
>+++ gcc/testsuite/g++.dg/lto/pr91572_0.C	2019-08-28 18:13:41.695436342
>+0200
>@@ -0,0 +1,12 @@
>+// PR lto/91572
>+// { dg-lto-do link }
>+// { dg-lto-options { { -O -fPIC -flto } } }
>+// { dg-require-effective-target shared }
>+// { dg-require-effective-target fpic }
>+// { dg-extra-ld-options "-shared" }
>+
>+void foo (char);
>+namespace N {
>+  class A { A (); };
>+  A::A () { asm ("" : : "g" (0)); }
>+}
>
>	Jakub