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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>In DWARF v3, section 7.20 deals with the structure of the debug_aranges section. Near the end, there is the following paragraph:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'>“This header is followed by a series of tuples. Each tuple consists of an address and a length, each in the size appropriate for an address on the target architecture. The first tuple following the header in each set begins at an offset that is a multiple of the size of a single tuple (that is, twice the size of an address). The header is padded, if necessary, to the appropriate boundary. Each set of tuples is terminated by a 0 for the address and 0 for the length.”<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'>Note the third sentence:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'>“The first tuple following the header in each set begins at an offset that is a multiple of the size of a single tuple (that is, twice the size of an address).”<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'>Meanwhile in DWARFv4, section 6.1.2, which describes the same, the corresponding fragment goes:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.5pt;color:black'><o:p> </o:p></span></p><p class=Default style='mso-margin-top-alt:5.0pt;margin-right:0cm;margin-bottom:5.0pt;margin-left:0cm'><span style='font-size:11.5pt'>“</span><span style='font-size:11.5pt'>This header is followed by a variable number of address range descriptors. Each descriptor is a triple consisting of a segment selector, the beginning address within that segment of a range of text or data covered by some entry owned by the corresponding compilation unit, followed by the non-zero length of that range. A particular set is terminated by an entry consisting of three zeroes. When the segment_size value is zero in the header, the segment selector is omitted so that each descriptor is just a pair, including the terminating entry. By scanning the table, a debugger can quickly decide which compilation unit to look in to find the debugging information for an object that has a given address. <o:p></o:p></span></p><p class=MsoNormal><i><span style='font-size:11.5pt'>If the range of addresses covered by the text and/or data of a compilation unit is not contiguous, then there may be multiple address range descriptors for that compilation unit.”<o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-size:11.5pt'><o:p> </o:p></span></i></p><p class=MsoNormal><span style='font-size:11.5pt'>Note that there is no mention of the triple/tuple alignment requirement. The version number in the aranges CU header is supposed to be 2 both in DWARF v4 and DWARF v3. Meanwhile, the alignment or lack thereof does make a difference for a parser. Is there a preferred way to disambiguate?</span><o:p></o:p></p></div></body></html>