[binutils-gdb] [gdb/testsuite] Fix .debug_aranges in watch-loc.c

[binutils-gdb] [gdb/testsuite] Fix .debug_aranges in watch-loc.c

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=75f06e9dc59d3f810e2afe2f47afbcb74204ef61

commit 75f06e9dc59d3f810e2afe2f47afbcb74204ef61
Author: Tom de Vries <tdevries@suse.de>
Date:   Tue May 7 10:58:57 2019 +0200

    [gdb/testsuite] Fix .debug_aranges in watch-loc.c
    
    When running gdb.dlang/watch-loc.exp with target board cc-with-debug-names, we
    run into:
    ...
    FAIL: gdb.dlang/watch-loc.exp: disassemble _Dmain (GDB internal error)
    ...
    in more detail:
    ...
    (gdb) disassemble _Dmain
    gdb/dwarf2read.c:5293: internal-error: \
      compunit_symtab* dw2_find_pc_sect_compunit_symtab(objfile*, \
      bound_minimal_symbol, CORE_ADDR, obj_section*, int): \
      Assertion `result != NULL' failed.
    ...
    
    The problem is that the .debug_aranges section in watch-loc.c contains a
    debug_info_offset which is set to 0:
    ...
    asm (
      "      .pushsection    .debug_aranges,\"\",%progbits\n"
      "      .4byte  .Laranges_end - .Laranges_start\n"
      ".Laranges_start:\n"
      "      .2byte  0x2\n"
      "      .4byte  0\n"
    ...
    while the compilation unit at offset 0 in the .debug_section in the executable
    is in fact not the compilation unit generated from watch-loc-dw.S.
    
    [ Note: this is a non-trivial test-case.  The file watch-loc-dw.S contains a
    .debug_info section, but not an .debug_aranges section or any actual code.
    The file watch-loc.c contains code and a .debug_aranges section, but no other
    debug section.  So, the intent for the .debug_aranges section in watch-loc.c
    is to refer to a compilation unit in the .debug_info section in
    watch-loc-dw.S. ]
    
    This happens when linked in object files contain dwarf info and are placed in
    the .debug_info section before the compilation units generated from
    watch-loc.c and watch-loc-dw.S.
    
    Fix this by defining the debug_info_offset field using a label .Lcu1_begin
    that defines the start of an empty .debug_section compilation unit:
    ...
     asm (
    +  "      .pushsection    .debug_info,\"\",%progbits\n"
    +  ".Lcu1_begin:"
    +  "      .popsection\n"
       "      .pushsection    .debug_aranges,\"\",%progbits\n"
       "      .4byte  .Laranges_end - .Laranges_start \n"
       ".Laranges_start:\n"
       "      .2byte  0x2\n"
    -  "      .4byte  0\n"
    +  "      .4byte  .Lcu1_begin\n"
    ...
    which during linking merges with the start of the .debug_info section of
    watch-loc-dw.S.
    
    Tested on x86_64-linux with native, cc-with-gdb-index and cc-with-debug-names.
    
    gdb/testsuite/ChangeLog:
    
    2019-05-07  Tom de Vries  <tdevries@suse.de>
    
    	PR testsuite/24522
    	* gdb.dlang/watch-loc.c: Fix debug_info_offset in .debug_aranges
    	section.

Diff:
---
 gdb/testsuite/ChangeLog             | 6 ++++++
 gdb/testsuite/gdb.dlang/watch-loc.c | 5 ++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c514c03..0af0d37 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,6 +1,12 @@
 2019-05-07  Tom de Vries  <tdevries@suse.de>
 
 	PR testsuite/24522
+	* gdb.dlang/watch-loc.c: Fix debug_info_offset in .debug_aranges
+	section.
+
+2019-05-07  Tom de Vries  <tdevries@suse.de>
+
+	PR testsuite/24522
 	* gdb.dwarf2/dw2-case-insensitive-debug.S: Fix debug_info_offset in
 	.debug_aranges section.
 
diff --git a/gdb/testsuite/gdb.dlang/watch-loc.c b/gdb/testsuite/gdb.dlang/watch-loc.c
index b0af2fc..5dd05b4 100644
--- a/gdb/testsuite/gdb.dlang/watch-loc.c
+++ b/gdb/testsuite/gdb.dlang/watch-loc.c
@@ -38,11 +38,14 @@ main (void)
    generated by GCC.  (.gdb_index includes a gdb-generated map
    instead.)  */
 asm (
+"	.pushsection	.debug_info,\"\",%progbits \n"
+".Lcu1_begin:"
+"	.popsection \n"
 "	.pushsection	.debug_aranges,\"\",%progbits \n"
 "	.4byte	.Laranges_end - .Laranges_start \n"	// Length of Address Ranges Info
 ".Laranges_start: \n"
 "	.2byte	0x2 \n"	// DWARF Version
-"	.4byte	0 \n" // .Ldebug_info0 - Offset of Compilation Unit Info
+"	.4byte	.Lcu1_begin\n" // .Ldebug_info0 - Offset of Compilation Unit Info
 "	.byte	4 \n"	// Size of Address
 "	.byte	0 \n"	// Size of Segment Descriptor
 "	.2byte	0 \n"	// Pad to 16 byte boundary