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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hey <o:p></o:p></p>
<p class="MsoNormal">I’m working on adding support for inline asm to LLVM.org.<o:p></o:p></p>
<p class="MsoNormal">I am trying to determine what is the best place to insert code to enable use of enumerated constants<o:p></o:p></p>
<p class="MsoNormal">when using Microsoft style inline asm in a similar fashion to the way macros are used.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">EXAMPLE:<o:p></o:p></p>
<p class="MsoNormal">########################################################################################################<o:p></o:p></p>
<p class="MsoNormal">C code:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">int test_inline_asm_enum() {<o:p></o:p></p>
<p class="MsoNormal"> enum { A = 12, B}; // can also be declared globally<o:p></o:p></p>
<p class="MsoNormal"> __asm mov ax, A<o:p></o:p></p>
<p class="MsoNormal"> return B;<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Generated LLVM IR:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">define i32 @test_inline_asm_enum() #0 {<o:p></o:p></p>
<p class="MsoNormal">entry: <o:p></o:p></p>
<p class="MsoNormal">call void asm sideeffect inteldialect \<o:p></o:p></p>
<p class="MsoNormal">"mov ax, <b>qword ptr </b>A", "~{dirflag},~{fpsr},~{flags}"() #1, !srcloc !1
<o:p></o:p></p>
<p class="MsoNormal">ret i32 13<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">COMPILE LINE:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Clang -cc1 -fasm-blocks -O0 -emit-llvm <codefile.c> -o -<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">* without –emit-llvm flag the compiler will crash as it tries to handles A like a variable.<o:p></o:p></p>
<p class="MsoNormal">** note the absence of an allocation of A before the function call, this is because enums are
<o:p></o:p></p>
<p class="MsoNormal">not emitted to IR but treated as integer constants.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">########################################################################################################<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">After some investigation I narrowed the scope to two locations in clang which are reasonable candidates:<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span dir="LTR"></span>buildMsAsmString – where macros are handled<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span dir="LTR"></span>asmParser/X86 AsmParser which handles the assembly semantics and emits the IR.<o:p></o:p></p>
<p class="MsoListParagraph"><o:p> </o:p></p>
<p class="MsoNormal">My main issue though is to determine if the token/identifier belongs to an EnumConstDecl/Expr.<o:p></o:p></p>
<p class="MsoNormal">I’ve noticed the code in this area uses a lookup method which is called via parser->semaCallback.<o:p></o:p></p>
<p class="MsoNormal">However I don’t really understand yet how to create an instance of such a handler in order to lookup<o:p></o:p></p>
<p class="MsoNormal">previously declared labels(particularly EnumConstantDecls).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was hoping that someone may have some insight to share regarding the problem or on lookup usage in general.<o:p></o:p></p>
<p class="MsoNormal">Please let me know if you need any clarifications and feel free to contact me via mail.<o:p></o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Matan Haroush<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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