[PATCH] Fix PR debug/19345

[Daniel Berlin]

Now that we actually exercise our debug info functions more, we are 
starting to hit corner cases and expose a few latent bugs.

In this case, a 4.0 regression,  we were trying to generate the inlined 
structure type die 
for the 
structure inside the asm, and when we went to add the abstract origin 
attribute:

1. we fall into the TREE_CODE (origin) != FUNCTION_DECL portion, because 
gen_inlined_structure_type_die always passes in the type as the origin.

2. We get TYPE_STUB_DECL (origin) because origin is a RECORD_TYPE.

3. TYPE_STUB_DECL (origin) is NULL.

4. We pass null to decl_function_context.

5. decl_function_context dereferences it, and we blow up.

This means we never could have been trying to generate debug info for this 
inlined structure type before, since i didn't touch this code path, and 
this didn't fail in 3.4.

Compiling with 3.4 confirms this.  There is no inlined structure type die 
generated.

Rather than add a null check in decl_function_context, i've simply guarded 
against calling it here with null (we already were assuming it could 
return null, so what's 2 null checks when you've already got 1 :P).
Everything else DTRT once we exit our if block.

Bootstrapped and regtested on i686-pc-linux-gnu.  Okay for mainline?
-------------- next part --------------
2005-01-26  Daniel Berlin  <dberlin@dberlin.org>
	
	Fix PR debug/19345

	* dwarf2out.c (add_abstract_origin_attribute): TYPE_STUB_DECL is
	not always going to give us a non-NULL result, so guard against that.

Index: dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.568
diff -u -p -r1.568 dwarf2out.c
--- dwarf2out.c	20 Jan 2005 20:09:22 -0000	1.568
+++ dwarf2out.c	27 Jan 2005 03:17:40 -0000
@@ -10497,8 +10497,12 @@ add_abstract_origin_attribute (dw_die_re
 
       if (TYPE_P (fn))
 	fn = TYPE_STUB_DECL (fn);
+      
+      /* TYPE_STUB_DECL may have given us a NULL, which decl_function_context
+	 won't like.  */
+      if (fn)	
+	fn = decl_function_context (fn);
 
-      fn = decl_function_context (fn);
       if (fn)
 	dwarf2out_abstract_function (fn);
     }
Index: testsuite/gcc.dg/pr19345.c
===================================================================
RCS file: testsuite/gcc.dg/pr19345.c
diff -N testsuite/gcc.dg/pr19345.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gcc.dg/pr19345.c	27 Jan 2005 03:17:52 -0000
@@ -0,0 +1,13 @@
+/* We shouldn't crash trying to produce the inlined structure type die debug info.  */
+/* { dg-do compile } */
+/* { dg-options "-O1 -g" } */
+inline void bar(char a[], unsigned int l)
+{
+	asm volatile ("" :: "m" ( *(struct {char x[l]; } *)a));
+}
+
+void foo(void)
+{
+	bar (0, 0);
+}
+