Re: [patch] PR symtab/13277: Resolving opaque structures in ICC generated binaries.

[John Steele Scott <toojays@toojays.net>]

Hi Jan,

Jan Kratochvil <jan.kratochvil@redhat.com> writes:

> [ Cc to gdb-patches has been lost.  ]
> On Sun, 20 May 2012 15:09:19 +0200, Jan Kratochvil wrote:
> Hi John,
>
> On Sun, 20 May 2012 14:34:05 +0200, John Steele Scott wrote:
>> basic_lookup_transparent_type will only do one psymbol->symbol expansion per
>> call. For a frequently referenced opaque type in a non-trivial program,
>> initially "ptype" will show it as "no data fields". But if I repeatedly
>> invoke ptype, eventually it resolves the type correctly.
>
> sorry I did not write a proper reproducer + testcase for it but I believe the
> attached patch should fix it.  It is probably a regression since introduction
> of quick_symbol_functions.
>
>
>> On the question of caching the producer info in the dwarf2_cu; I propose to
>> extract out the second half of producer_is_gxx_lt_4_6 into a new
>> check_producer function which will set cu->producer_is_gxx_lt_4_6 and
>> cu->producer_is_icc as appropriate (and then set cu->checked_producer).
>> producer_is_gxx_lt_4_6 and producer_is_icc will call check_producer if
>> cu->checked_producer is not set. Sound okay?
>
> Yes, I find such approach appropriate.

The below patch implements this.

I ran the full testsuite on amd64 with gcc (Ubuntu/Linaro 4.4.4-14ubuntu5.1)
4.4.5; it passes my testcase from
http://sourceware.org/ml/gdb-patches/2012-05/msg00763.html, and there are no
new failures.

I also ran the full testsuite with icc, as:
make -j10 check RUNTESTFLAGS="CC_FOR_TARGET=icc CFLAGS_FOR_TARGET='-debug
extended' CXX_FOR_TARGET=icpc CXXFLAGS_FOR_TARGET='-debug extended'". In
addition to fixing my testcase, this fixes the four similar broken cases in
gdb.base/opaque, now that set of tests all pass.

Two tests in gdb.base/type-opaque effectively changed polarity: previously
"opaque {struct,union} type resolving" failed, now those pass and "empty
{struct,union} type resolving" fail. As previously discussed, this is the
lesser of the two evils as far as I'm concerned.

The patch at http://sourceware.org/ml/gdb-patches/2012-05/msg00739.html is
still required to fix my non-trivial case, I hope that (or something like it)
can be committed soon.

thanks,

John

2012-05-24  John Steele Scott  <toojays@toojays.net>

	PR symtab/13277: Resolving opaque structures in ICC generated binaries.
	* dwarf2read.c (struct dwarf2_cu) <producer_is_icc>: New field.
	(producer_is_gxx_lt_4_6): Move the checking and caching to...
	(check_producer): ... this new function, which also checks for ICC
	and caches the result.
	(producer_is_icc): New function.
	(read_structure_type): Don't set TYPE_STUB_SUPPORTED if the
	producer was ICC.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index b590134..2afefaf 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -429,12 +429,13 @@ struct dwarf2_cu
      unoptimized code.  For a future better test see GCC PR other/32998.  */
   unsigned int has_loclist : 1;
 
-  /* These cache the results of producer_is_gxx_lt_4_6.
-     CHECKED_PRODUCER is set if PRODUCER_IS_GXX_LT_4_6 is valid.  This
-     information is cached because profiling CU expansion showed
-     excessive time spent in producer_is_gxx_lt_4_6.  */
+  /* These cache the results for producer_is_gxx_lt_4_6 and producer_is_icc.
+     CHECKED_PRODUCER is set if both PRODUCER_IS_GXX_LT_4_6 and PRODUCER_IS_ICC
+     are valid.  This information is cached because profiling CU expansion
+     showed excessive time spent in producer_is_gxx_lt_4_6.  */
   unsigned int checked_producer : 1;
   unsigned int producer_is_gxx_lt_4_6 : 1;
+  unsigned int producer_is_icc : 1;
 
   /* Non-zero if DW_AT_addr_base was found.
      Used when processing DWO files.  */
@@ -8271,16 +8272,14 @@ dwarf2_record_block_ranges (struct die_info *die, struct block *block,
     }
 }
 
-/* Check for GCC PR debug/45124 fix which is not present in any G++ version up
-   to 4.5.any while it is present already in G++ 4.6.0 - the PR has been fixed
-   during 4.6.0 experimental.  */
+/* Check whether the producer field indicates either of GCC < 4.6, or the
+   Intel C/C++ compiler, and cache the result in CU.  */
 
-static int
-producer_is_gxx_lt_4_6 (struct dwarf2_cu *cu)
+static void
+check_producer (struct dwarf2_cu *cu)
 {
   const char *cs;
   int major, minor, release;
-  int result = 0;
 
   if (cu->producer == NULL)
     {
@@ -8292,22 +8291,11 @@ producer_is_gxx_lt_4_6 (struct dwarf2_cu *cu)
 	 for their space efficiency GDB cannot workaround gcc-4.5.x -gdwarf-4
 	 combination.  gcc-4.5.x -gdwarf-4 binaries have DW_AT_accessibility
 	 interpreted incorrectly by GDB now - GCC PR debug/48229.  */
-
-      return 0;
-    }
-
-  if (cu->checked_producer)
-    return cu->producer_is_gxx_lt_4_6;
-
-  /* Skip any identifier after "GNU " - such as "C++" or "Java".  */
-
-  if (strncmp (cu->producer, "GNU ", strlen ("GNU ")) != 0)
-    {
-      /* For non-GCC compilers expect their behavior is DWARF version
-	 compliant.  */
     }
-  else
+  else if (strncmp (cu->producer, "GNU ", strlen ("GNU ")) == 0)
     {
+      /* Skip any identifier after "GNU " - such as "C++" or "Java".  */
+
       cs = &cu->producer[strlen ("GNU ")];
       while (*cs && !isdigit (*cs))
 	cs++;
@@ -8316,13 +8304,30 @@ producer_is_gxx_lt_4_6 (struct dwarf2_cu *cu)
 	  /* Not recognized as GCC.  */
 	}
       else
-	result = major < 4 || (major == 4 && minor < 6);
+	cu->producer_is_gxx_lt_4_6 = major < 4 || (major == 4 && minor < 6);
+    }
+  else if (strncmp (cu->producer, "Intel(R) C", strlen ("Intel(R) C")) == 0)
+    cu->producer_is_icc = 1;
+  else
+    {
+      /* For other non-GCC compilers, expect their behavior is DWARF version
+	 compliant.  */
     }
 
   cu->checked_producer = 1;
-  cu->producer_is_gxx_lt_4_6 = result;
+}
 
-  return result;
+/* Check for GCC PR debug/45124 fix which is not present in any G++ version up
+   to 4.5.any while it is present already in G++ 4.6.0 - the PR has been fixed
+   during 4.6.0 experimental.  */
+
+static int
+producer_is_gxx_lt_4_6 (struct dwarf2_cu *cu)
+{
+  if (!cu->checked_producer)
+    check_producer(cu);
+
+  return cu->producer_is_gxx_lt_4_6;
 }
 
 /* Return the default accessibility type if it is not overriden by
@@ -9005,6 +9010,18 @@ quirk_gcc_member_function_pointer (struct type *type, struct objfile *objfile)
   smash_to_methodptr_type (type, new_type);
 }
 
+/* Return non-zero if the CU's PRODUCER string matches the Intel C/C++ compiler
+   (icc).  */
+
+static int
+producer_is_icc (struct dwarf2_cu *cu)
+{
+  if (!cu->checked_producer)
+    check_producer(cu);
+
+  return cu->producer_is_icc;
+}
+
 /* Called when we find the DIE that starts a structure or union scope
    (definition) to create a type for the structure or union.  Fill in
    the type's name and general properties; the members will not be
@@ -9107,7 +9124,14 @@ read_structure_type (struct die_info *die, struct dwarf2_cu *cu)
       TYPE_LENGTH (type) = 0;
     }
 
-  TYPE_STUB_SUPPORTED (type) = 1;
+  if (producer_is_icc (cu))
+    {
+      /* ICC does not output the required DW_AT_declaration
+	 on incomplete types, but gives them a size of zero.  */
+    }
+  else
+    TYPE_STUB_SUPPORTED (type) = 1;
+
   if (die_is_declaration (die, cu))
     TYPE_STUB (type) = 1;
   else if (attr == NULL && die->child == NULL