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Can you please be more specific about the imported directives, such
as the names of related classes? I'm totally new to Clang and only
used little about LLVM.<br>
<br>
I took a look at clang::CodeGen::CGDebugInfo and it seems that it
uses llvm::DIBuilder as the underlying horsepower. I played with the
if statements related to "isDefinition" in DIBuilder::createFunction
and DIBuilder::createMethod, and it didn't work. Obviously, I've
missed many things here.<br>
<br>
Since generating debug info metadata has been done for function
definitions, so conceptually generating the same type of data for
declarations should be easier. I might be wrong though. The more
specific you can point me to some code, the better.<br>
<br>
Thanks very much,<br>
<br>
<div class="moz-cite-prefix">On 11/09/2013 02:23 PM, David Blaikie
wrote:<br>
</div>
<blockquote
cite="mid:CAENS6EvaaHMCgEaYvhOtqRhkCX2fABVWSKMinNDAPj_77PTgyQ@mail.gmail.com"
type="cite">
<p dir="ltr">Generally we don't encourage source to source
translation via code generation from the AST even - its best to
use the AST to motivate edits to the original source. The AST
just doesn't have the fidelity to regenerate the original source
perfectly.</p>
<p dir="ltr">As for your current problem, I guess 'is it cheaper
to rewrite in a better way' depends on the complexity, but i
assume its hard to justify a rewrite unless this tool is going
to live a long time further and need new features/maintenance.</p>
<p dir="ltr">That said, I'm not sure how much I can help you
produce debug info for every function declaration. If I were
doing this I'd go back and look at the support I added for
imported directives (using declarations and directives) and look
at other unhandled decks that could be supported. </p>
<div class="gmail_quote">On Nov 9, 2013 10:18 AM, "Lewis Burns"
<<a moz-do-not-send="true" href="mailto:lewisurn@gmail.com">lewisurn@gmail.com</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>I'm fixing an existing source-to-source translator, and
it was unfortunately written by someone using LLVM as the
intermediate step before Clang was mature. I don't need to
generate object code at all, and performance is not a
concern here.<br>
<br>
Sounds like that the only way for me to save this
translator is to patch Clang by generating debug info
metadata for declarations whose definitions are not
available. Is this a feasible approach? I mean how
difficult it would be comparing with hacking into Clang
AST and start from there? I guessed that it would be much
easier than starting over with Clang AST from scratch.
Since I haven't worked on Clang before, any suggestion and
help would be greatly appreciated.<br>
<br>
<br>
<br>
On 11/09/2013 04:14 PM, David Blaikie wrote:<br>
</div>
<blockquote type="cite">
<p dir="ltr">For those following this thread a critical
detail would be that you want debug info metadata.</p>
<p dir="ltr">There's no simple flag for this as we don't
attach the function debug info metadata to every
declaration, just to definitions (there's no filtering
step)</p>
<p dir="ltr">But why do you want this anyway? If you're
performing optimizations/transformations based on debug
info metadata, that's not really the desired approach.
Debug info is not meant to affect code generation.</p>
<div class="gmail_quote">On Nov 9, 2013 7:59 AM, "Lewis
Burns" <<a moz-do-not-send="true"
href="mailto:lewisurn@gmail.com" target="_blank">lewisurn@gmail.com</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> Hi,<br>
<br>
I haven't worked on Clang before and have a simple
question (supposedly) for those who are familiar
with metadata and LLVM bitcode generation. Assume
that I have a function which is declared as extern
as the following:<br>
<br>
<font face="Courier New, Courier, monospace">extern
int convert(unsigned u);</font><br>
<br>
I want to have Clang generate metadata nodes for it
by adding a metadata node of subprogram into the
list of subprograms defined in the current
compilation unit. The subprogram metadata node and
its associated nodes should have the info of the
type signature. For example, I get the following set
of metadata nodes for function<br>
<font face="Courier New, Courier, monospace"><br>
int convert(unsigned u) {return 0;}<br>
<br>
!3 = metadata !{metadata !4, metadata !10,
metadata !33}<br>
!4 = metadata !{i32 786478, metadata !1, metadata
!5, metadata !"convert", metadata !"convert",
metadata !"", i32 23, metadata !6, i1 false, i1
true, i32 0, i32 0, null, i32 256, i1 false, i32
(i32)* @convert, null, null, metadata !2, i32 23}
; [ DW_TAG_subprogram ] [line 23] [def] [convert]<br>
!7 = metadata !{metadata !8, metadata !9}<br>
!8 = metadata !{i32 786468, null, null, metadata
!"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32
5} ; [ DW_TAG_base_type ] [int] [line 0, size 32,
align 32, offset 0, enc DW_ATE_signed]<br>
!9 = metadata !{i32 786468, null, null, metadata
!"unsigned int", i32 0, i64 32, i64 32, i64 0, i32
0, i32 7} ; [ DW_TAG_base_type ] [unsigned int]
[line 0, size 32, align 32, offset 0, enc
DW_ATE_unsigned]<br>
</font><br>
which allows me to extract the source-level type
signature for the function by using LLVM debug info
APIs. I'd like to get the source-level type
signature of the extern declared function, but Clang
does not produce metadata for it.<br>
<br>
By looking at the Clang AST for the extern declared
function<br>
<br>
<font face="Courier New, Courier, monospace">|-FunctionDecl
0x70598c0 <line:23:1, col:30> convert 'int
(unsigned int)' extern<br>
| |-ParmVarDecl 0x7059800 <col:20, col:29> u
'unsigned int'<br>
</font><br>
I know that Clang has the information I need, and I
just need to turn off or remove the filter that
ignores functions whose bodies are not available
during metadata node or/and code generation. Are
there simple switches that do this? If not, can
anyone please explain how to do it by pointing me to
the right code snippets?<br>
<br>
Thanks very much,<br>
<br>
<pre cols="72">--
Lewis</pre>
</div>
<br>
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</blockquote>
</div>
</blockquote>
<br>
<br>
<pre cols="72">--
Lewis</pre>
</div>
</blockquote>
</div>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Lewis</pre>
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