<div dir="ltr">I tend to think it's more legible if we include the values there, even if no bytes were required to produce them. I don't generally look at the abbreviations when reading a dump & expect to see the data in the debug_info/debug_types output.<br><br>( <a class="GWVZpf gW" id="IloFPc-3" href="mailto:aprantl@apple.com" tabindex="-1">+Adrian Prantl</a> <a class="GWVZpf gW" id="IloFPc-2" href="mailto:echristo@gmail.com" tabindex="-1">+Eric Christopher</a> in case they've got thoughts on the subject)<br><br><div class="gmail_quote"><div dir="ltr">On Mon, Feb 27, 2017 at 11:09 AM Victor Leschuk <<a href="mailto:vleschuk@accesssoftek.com">vleschuk@accesssoftek.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<p class="gmail_msg">Yeah, I see, I was wrong. I agree that we need to make behavior
uniform here. However I still think we shouldn't include the data
which is not really present into dump. It seems more logical for
me to not print flag_present values either.</p>
<p class="gmail_msg">What do you think?</p></div><div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<div class="m_-1917743091071114938moz-cite-prefix gmail_msg">On 02/27/2017 09:54 PM, David Blaikie
wrote:<br class="gmail_msg">
</div>
<blockquote type="cite" class="gmail_msg">
<div dir="ltr" class="gmail_msg"><br class="gmail_msg">
<br class="gmail_msg">
<div class="gmail_quote gmail_msg">
<div dir="ltr" class="gmail_msg">On Mon, Feb 27, 2017 at 10:30 AM Victor Leschuk
<<a href="mailto:vleschuk@accesssoftek.com" class="gmail_msg" target="_blank">vleschuk@accesssoftek.com</a>>
wrote:<br class="gmail_msg">
</div>
<blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<p class="gmail_msg">I think flag_present and
implicit_const attributes shouldn't be treated as
similar here: flag_present attributes physically do have
a record in .debug_info section,</p>
</div>
</blockquote>
<div class="gmail_msg"><br class="gmail_msg">
I think one of us is confused, because my understanding is
that flag_present attributes do not have any bit/bytes in
the debug_info representation.<br class="gmail_msg">
<br class="gmail_msg">
To take the same example as before and look at the assembly:<br class="gmail_msg">
<br class="gmail_msg">
this is the debug_info assembly for that subprogram:<br class="gmail_msg">
<font face="monospace" class="gmail_msg"><br class="gmail_msg">
</font>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .byte 2
# Abbrev [2] 0x2a:0x19 DW_TAG_subprogram</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .quad .Lfunc_begin0
# DW_AT_low_pc</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .long
.Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .byte 1
# DW_AT_frame_base</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .byte 86</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .long .Linfo_string3
# DW_AT_linkage_name</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .long .Linfo_string4
# DW_AT_name</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .byte 1
# DW_AT_decl_file</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .byte 1
# DW_AT_decl_line</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg">
# DW_AT_external</font></div>
<div class="gmail_msg"><font face="monospace" class="gmail_msg"> .byte 0
# End Of Children Mark</font></div>
<br class="gmail_msg">
Note that no bytes were produced for the DW_AT_external
(using DW_FORM_flag_present in the abbrev) attribute.<br class="gmail_msg">
<br class="gmail_msg">
From the DWARF4 spec:<br class="gmail_msg">
<br class="gmail_msg">
"A flag is represented explicitly as a single byte of data
(DW_FORM_flag) or implicitly
(DW_FORM_flag_present). In the first case, if the flag has
value zero, it indicates the
absence of the attribute; if the flag has a non-zero value,
it indicates the presence of the
attribute. In the second case, the attribute is implicitly
indicated as present, and no value is
encoded in the debugging information entry itself."<br class="gmail_msg">
</div>
<blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<p class="gmail_msg"> while implicit_const attributes are
not physically mentioned there. Printing implicit_const
values when dumping .debug_info can be more convenient
for reader but it will actually violate the definition
of dump. When dumping section contents we expect to see
what is actually there, don't we?<br class="gmail_msg">
</p>
</div>
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg"> <br class="gmail_msg">
<div class="m_-1917743091071114938m_-7804286437102967308moz-cite-prefix gmail_msg">On 02/27/2017 09:04 PM, David Blaikie wrote:<br class="gmail_msg">
</div>
<blockquote type="cite" class="gmail_msg">
<div dir="ltr" class="gmail_msg"><br class="gmail_msg">
<br class="gmail_msg">
<div class="gmail_quote gmail_msg">
<div dir="ltr" class="gmail_msg">On Mon, Feb 27,
2017 at 10:00 AM Victor Leschuk <<a href="mailto:vleschuk@accesssoftek.com" class="gmail_msg" target="_blank">vleschuk@accesssoftek.com</a>>
wrote:<br class="gmail_msg">
</div>
<blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<p class="gmail_msg"><br class="gmail_msg">
</p>
<br class="gmail_msg">
<div class="m_-1917743091071114938m_-7804286437102967308m_-7636712434836838175moz-cite-prefix gmail_msg">On 02/27/2017 08:04 PM, David
Blaikie wrote:<br class="gmail_msg">
</div>
<blockquote type="cite" class="gmail_msg">
<div dir="ltr" class="gmail_msg">Skipping
these values doesn't seem to be correct - in
the case of flag_present, I think the value
is still rendered in the dump, is it not?</div>
</blockquote>
</div>
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg"> Do you mean that the value is
somehow mentioned in .debug_info section? It is
not.</div>
</blockquote>
<div class="gmail_msg"><br class="gmail_msg">
Looks to me like it is:<br class="gmail_msg">
<br class="gmail_msg">
dumping debug info for this code: void f1() { }<br class="gmail_msg">
<br class="gmail_msg">
produces this:<br class="gmail_msg">
<br class="gmail_msg">
<font class="gmail_msg" face="monospace">
.debug_abbrev contents:<br class="gmail_msg">
...<br class="gmail_msg">
</font>
<div class="gmail_msg"><font class="gmail_msg" face="monospace"> [2] DW_TAG_subprogram
DW_CHILDREN_no</font></div>
<div class="gmail_msg"><font class="gmail_msg" face="monospace"> ...</font></div>
<div class="gmail_msg"><font class="gmail_msg" face="monospace"> DW_AT_external
DW_FORM_flag_present<br class="gmail_msg">
<br class="gmail_msg">
.debug_info contents:<br class="gmail_msg">
...<br class="gmail_msg">
0x0000002a: DW_TAG_subprogram [2]<br class="gmail_msg">
...<br class="gmail_msg">
DW_AT_external
[DW_FORM_flag_present] (true)</font></div>
<br class="gmail_msg">
</div>
<div class="gmail_msg">I would expect similar
behavior for const_value - that the attribute and
its constant value is printed in the debug_info
dump.<br class="gmail_msg">
<br class="gmail_msg">
</div>
<blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg"><br class="gmail_msg">
<blockquote type="cite" class="gmail_msg">
<div dir="ltr" class="gmail_msg"> I would
expect the same for implicit_const values.
(also, this needs test coverage either way)</div>
</blockquote>
</div>
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg"> Yes, you are correct. I will
create tests when we decide what's right
behavior here. <br class="gmail_msg">
<br class="gmail_msg">
I think skipping is correct here: we are dumping
.debug_info data based on attributes stored in
AbbrevDecl, this code was based on assumption
that every attribute has representation in
.debug_info section, that was before
implicit_const form was introduced.</div>
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg"><br class="gmail_msg">
<blockquote type="cite" class="gmail_msg"><br class="gmail_msg">
<div class="gmail_quote gmail_msg">
<div dir="ltr" class="gmail_msg">On Sat, Feb
25, 2017 at 5:27 AM Victor Leschuk via
llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" class="gmail_msg" target="_blank">llvm-commits@lists.llvm.org</a>>
wrote:<br class="gmail_msg">
</div>
<blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author:
vleschuk<br class="gmail_msg">
Date: Sat Feb 25 07:15:57 2017<br class="gmail_msg">
New Revision: 296253<br class="gmail_msg">
<br class="gmail_msg">
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=296253&view=rev" rel="noreferrer" class="gmail_msg" target="_blank">http://llvm.org/viewvc/llvm-project?rev=296253&view=rev</a><br class="gmail_msg">
Log:<br class="gmail_msg">
[DebugInfo] Skip implicit_const attributes
when dumping .debug_info. NFC.<br class="gmail_msg">
<br class="gmail_msg">
When dumping .debug_info section we loop
through all attributes mentioned in<br class="gmail_msg">
.debug_abbrev section and dump values
using DWARFFormValue::extractValue().<br class="gmail_msg">
We need to skip implicit_const attributes
here as their values are not<br class="gmail_msg">
really located in .debug_info but directly
in .debug_abbrev. This patch fixes<br class="gmail_msg">
triggered assert() in
DWARFFormValue::extractValue() caused by
trying to<br class="gmail_msg">
access implicit_const values from
.debug_info.<br class="gmail_msg">
<br class="gmail_msg">
Modified:<br class="gmail_msg">
llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp<br class="gmail_msg">
<br class="gmail_msg">
Modified:
llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp<br class="gmail_msg">
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp?rev=296253&r1=296252&r2=296253&view=diff" rel="noreferrer" class="gmail_msg" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp?rev=296253&r1=296252&r2=296253&view=diff</a><br class="gmail_msg">
==============================================================================<br class="gmail_msg">
---
llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp
(original)<br class="gmail_msg">
+++
llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp
Sat Feb 25 07:15:57 2017<br class="gmail_msg">
@@ -329,6 +329,12 @@ void
DWARFDie::dump(raw_ostream &OS, uns<br class="gmail_msg">
<br class="gmail_msg">
// Dump all data in the DIE for
the attributes.<br class="gmail_msg">
for (const auto &AttrSpec :
AbbrevDecl->attributes()) {<br class="gmail_msg">
+ if (AttrSpec.Form ==
DW_FORM_implicit_const) {<br class="gmail_msg">
+ // We are dumping .debug_info
section ,<br class="gmail_msg">
+ // implicit_const attribute
values are not really stored here,<br class="gmail_msg">
+ // but in .debug_abbrev
section. So we just skip such attrs.<br class="gmail_msg">
+ continue;<br class="gmail_msg">
+ }<br class="gmail_msg">
dumpAttribute(OS, *this,
&offset, AttrSpec.Attr, AttrSpec.Form,<br class="gmail_msg">
Indent);<br class="gmail_msg">
}<br class="gmail_msg">
<br class="gmail_msg">
<br class="gmail_msg">
_______________________________________________<br class="gmail_msg">
llvm-commits mailing list<br class="gmail_msg">
<a href="mailto:llvm-commits@lists.llvm.org" class="gmail_msg" target="_blank">llvm-commits@lists.llvm.org</a><br class="gmail_msg">
<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits" rel="noreferrer" class="gmail_msg" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</a><br class="gmail_msg">
</blockquote>
</div>
</blockquote>
<br class="gmail_msg">
</div>
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<pre class="m_-1917743091071114938m_-7804286437102967308m_-7636712434836838175moz-signature gmail_msg" cols="72">--
Best Regards,
Victor</pre>
</div>
</blockquote>
</div>
</div>
</blockquote>
<br class="gmail_msg">
</div>
<div bgcolor="#FFFFFF" text="#000000" class="gmail_msg">
<pre class="m_-1917743091071114938m_-7804286437102967308moz-signature gmail_msg" cols="72">--
Best Regards,
Victor</pre>
</div>
</blockquote>
</div>
</div>
</blockquote>
<br class="gmail_msg">
</div><div bgcolor="#FFFFFF" text="#000000" class="gmail_msg"><pre class="m_-1917743091071114938moz-signature gmail_msg" cols="72">--
Best Regards,
Victor</pre>
</div></blockquote></div></div>