Re: [PATCH] testsuite/gdb.dwarf2: Fix for dw2-ifort-parameter failure on ARM

[Pedro Alves <palves@redhat.com>]

On 01/16/2014 10:26 AM, Omair Javaid wrote:
> 
> 
> On 01/16/2014 02:48 PM, Pedro Alves wrote:
>> On 01/16/2014 09:03 AM, Omair Javaid wrote:
>>
>>> There seemed no problem with how breakpoint addresses were being adjusted. 
>>> This test requires to build dwarf info by hand in dw2-ifort-parameter-debug.S
>>> using compile time addresses so in case of arm (thumb mode) the least
>>> significant bits of compile time address are set to 1. For that reason 
>>> 0x000083bd was being used as a breakpoint address func. 
>>
>> OOC, what does the compiler debug info usually do instead to avoid this?
>>
> 
> Here is what compiler generates when there are thumb functions to handle:
>         .thumb_func
>         .type func, %function
> func:
> .LFB0:
> 
> func is marked as thumb function and thus this func pointer will have the 
> lower bit set. While .LFB0: non thumb label will be used to mark function
> start address. Like this:         .4byte .LFB0 @ DW_AT_low_pc

Ah.  I wonder if this works for you (and everyone).

---
 gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter-debug.S | 4 ++--
 gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.c       | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter-debug.S b/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter-debug.S
index c7dd9be..6b08cb2 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter-debug.S
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter-debug.S
@@ -35,8 +35,8 @@
 	.uleb128	2			/* Abbrev: DW_TAG_subprogram */
 	.byte		1			/* DW_AT_external */
 	.ascii		"func\0"		/* DW_AT_name */
-	.4byte		func			/* DW_AT_low_pc */
-	.4byte		main			/* DW_AT_high_pc */
+	.4byte		func_addr		/* DW_AT_low_pc */
+	.4byte		main_addr		/* DW_AT_high_pc */
 
 	.uleb128	3			/* Abbrev: DW_TAG_formal_parameter */
 	.ascii		"param\0"		/* DW_AT_name */
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.c b/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.c
index 361c44d..c866b0f 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.c
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ifort-parameter.c
@@ -29,3 +29,9 @@ main (void)
   func ();
   return 0;
 }
+
+/* Addresses represented as data symbols, thus without Thumb (etc.)
+   mode bits.  The dw2-ifort-parameter-debug.S file uses this as
+   func's low_pc/high_pc.  */
+extern void *func_addr __attribute__ ((alias ("func")));
+extern void *main_addr __attribute__ ((alias ("main")));
-- 
1.7.11.7