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</o:shapelayout></xml><![endif]--></head><body lang=KO link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US>Hello, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Each TargetABI, /clang/lib/CodeGen/TargetInfo.cpp, should define a target-specific IR. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>This causes to generate a target-specific IR, which prevents IR from having target-neutrality. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>For example, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>On X86, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>llvm::Value *X86_32ABIInfo::EmitVAArg(llvm::Value *VAListAddr, QualType Ty,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> CodeGenFunction &CGF) const {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Type *BP = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Type *BPP = llvm::PointerType::getUnqual(BP);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> CGBuilderTy &Builder = CGF.Builder;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Value *VAListAddrAsBPP = Builder.CreateBitCast(VAListAddr, BPP,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> "ap");<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Value *Addr = Builder.CreateLoad(VAListAddrAsBPP, "ap.cur");<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Type *PTy =<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::PointerType::getUnqual(CGF.ConvertType(Ty));<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Value *AddrTyped = Builder.CreateBitCast(Addr, PTy);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> uint64_t Offset =<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::RoundUpToAlignment(CGF.getContext().getTypeSize(Ty) / 8, 4);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> llvm::Value *NextAddr =<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> Builder.CreateGEP(Addr, llvm::ConstantInt::get(CGF.Int32Ty, Offset),<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> "ap.next");<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> Builder.CreateStore(NextAddr, VAListAddrAsBPP);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> return AddrTyped;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>}<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>However, on ARM, the highlighted code is arm-specific, which breaks the portability. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>llvm::Value *ARMABIInfo::EmitVAArg(llvm::Value *VAListAddr, QualType Ty,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> CodeGenFunction &CGF) const {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>¡¦<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> // Handle address alignment for type alignment > 32 bits<o:p></o:p></span></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> uint64_t TyAlign = CGF.getContext().getTypeAlign(Ty) / 8;<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> if (TyAlign > 4) {<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> assert((TyAlign & (TyAlign - 1)) == 0 &&<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> "Alignment is not power of 2!");<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> llvm::Value *AddrAsInt = Builder.CreatePtrToInt(Addr, CGF.Int32Ty);<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> AddrAsInt = Builder.CreateAdd(AddrAsInt, Builder.getInt32(TyAlign - 1));<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> AddrAsInt = Builder.CreateAnd(AddrAsInt, Builder.getInt32(~(TyAlign - 1)));<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> Addr = Builder.CreateIntToPtr(AddrAsInt, BP);<o:p></o:p></span></i></b></p><p class=MsoNormal><b><i><span lang=EN-US style='color:black'> }<o:p></o:p></span></i></b></p><p class=MsoNormal style='text-indent:9.0pt'><span lang=EN-US>¡¦<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>}<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Any other builtins, __builtin_va_start, __builtin_va_end, and __builtin_va_copy, are of instrinsics, which would be translated to machine code later. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>Is there any reason why __builtin_va_arg is generated in IR, not in an intrinsic?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Sincerely yours, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>Jaemin Park. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>