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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">I am trying to support an experimental DSL that uses non-C identifiers, but I want to write the implementation of the runtime support libraries for this DSL in C. The compiler
is built using the LLVM v5.0.0 release branch.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">To do this I thought I could simply write:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">int foo() { return 42; } // The C implementation<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">asm(".alias nonCname foo"); // Make the non-C name be a synonym for the C implementation<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">If I compile with ‘</span><span style="font-size:12.0pt;font-family:"Courier New"">-S –emit-llvm</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’, the
LL file contains:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">module asm ".alias nonCname foo"<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">define i32 @foo() local_unnamed_addr #0 {<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New""> ret i32 42<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">That is, the inline-assembly precedes the function definition. The resulting assembly code for the target also has the ‘</span><span style="font-size:12.0pt;font-family:"Courier New"">.alias
nonCname foo</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’ before the definition for the function ‘</span><span style="font-size:12.0pt;font-family:"Courier New"">foo</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’.
When I edit the LL file to place the inline-assembly after the function definition, it makes no difference to the emitted assembly code for the target, it is still placed first.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Our assembler requires that the symbol being aliased has been defined before the ‘</span><span style="font-size:12.0pt;font-family:"Courier New"">.alias</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’
directive; but I can’t get LLVM to do this, and it aggregates all file-scoped (or module-scoped) inline assembly before the code generated for the functions and data.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Since the semantics of inline-assembly are very murky, I don’t know if this is a bug or by-design.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Is there anyway of writing C code that will preserve the relative ordering of file-scoped function, data and inline-assembly definitions?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"> MartinO<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
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