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			383 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			383 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//
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| //
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| //                     The LLVM Compiler Infrastructure
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| //
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| // This file is distributed under the University of Illinois Open Source
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| // License. See LICENSE.TXT for details.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #define DEBUG_TYPE "mcexpr"
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| #include "llvm/MC/MCExpr.h"
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| #include "llvm/ADT/Statistic.h"
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| #include "llvm/ADT/StringSwitch.h"
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| #include "llvm/MC/MCAsmLayout.h"
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| #include "llvm/MC/MCAssembler.h"
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| #include "llvm/MC/MCContext.h"
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| #include "llvm/MC/MCSymbol.h"
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| #include "llvm/MC/MCValue.h"
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| #include "llvm/Support/Debug.h"
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| #include "llvm/Support/raw_ostream.h"
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| #include "llvm/Target/TargetAsmBackend.h"
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| using namespace llvm;
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| 
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| namespace {
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| namespace stats {
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| STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
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| }
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| }
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| 
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| void MCExpr::print(raw_ostream &OS) const {
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|   switch (getKind()) {
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|   case MCExpr::Target:
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|     return cast<MCTargetExpr>(this)->PrintImpl(OS);
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|   case MCExpr::Constant:
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|     OS << cast<MCConstantExpr>(*this).getValue();
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|     return;
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| 
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|   case MCExpr::SymbolRef: {
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|     const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
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|     const MCSymbol &Sym = SRE.getSymbol();
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| 
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|     if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_HI16 ||
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| 	SRE.getKind() == MCSymbolRefExpr::VK_ARM_LO16)
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|       OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
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| 
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|     // Parenthesize names that start with $ so that they don't look like
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|     // absolute names.
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|     if (Sym.getName()[0] == '$')
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|       OS << '(' << Sym << ')';
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|     else
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|       OS << Sym;
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| 
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|     if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
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| 	SRE.getKind() != MCSymbolRefExpr::VK_ARM_HI16 &&
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| 	SRE.getKind() != MCSymbolRefExpr::VK_ARM_LO16)
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|       OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
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| 
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|     return;
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|   }
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| 
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|   case MCExpr::Unary: {
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|     const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
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|     switch (UE.getOpcode()) {
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|     default: assert(0 && "Invalid opcode!");
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|     case MCUnaryExpr::LNot:  OS << '!'; break;
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|     case MCUnaryExpr::Minus: OS << '-'; break;
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|     case MCUnaryExpr::Not:   OS << '~'; break;
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|     case MCUnaryExpr::Plus:  OS << '+'; break;
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|     }
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|     OS << *UE.getSubExpr();
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|     return;
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|   }
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| 
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|   case MCExpr::Binary: {
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|     const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
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| 
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|     // Only print parens around the LHS if it is non-trivial.
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|     if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
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|       OS << *BE.getLHS();
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|     } else {
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|       OS << '(' << *BE.getLHS() << ')';
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|     }
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| 
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|     switch (BE.getOpcode()) {
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|     default: assert(0 && "Invalid opcode!");
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|     case MCBinaryExpr::Add:
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|       // Print "X-42" instead of "X+-42".
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|       if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
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|         if (RHSC->getValue() < 0) {
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|           OS << RHSC->getValue();
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|           return;
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|         }
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|       }
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| 
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|       OS <<  '+';
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|       break;
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|     case MCBinaryExpr::And:  OS <<  '&'; break;
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|     case MCBinaryExpr::Div:  OS <<  '/'; break;
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|     case MCBinaryExpr::EQ:   OS << "=="; break;
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|     case MCBinaryExpr::GT:   OS <<  '>'; break;
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|     case MCBinaryExpr::GTE:  OS << ">="; break;
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|     case MCBinaryExpr::LAnd: OS << "&&"; break;
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|     case MCBinaryExpr::LOr:  OS << "||"; break;
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|     case MCBinaryExpr::LT:   OS <<  '<'; break;
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|     case MCBinaryExpr::LTE:  OS << "<="; break;
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|     case MCBinaryExpr::Mod:  OS <<  '%'; break;
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|     case MCBinaryExpr::Mul:  OS <<  '*'; break;
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|     case MCBinaryExpr::NE:   OS << "!="; break;
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|     case MCBinaryExpr::Or:   OS <<  '|'; break;
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|     case MCBinaryExpr::Shl:  OS << "<<"; break;
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|     case MCBinaryExpr::Shr:  OS << ">>"; break;
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|     case MCBinaryExpr::Sub:  OS <<  '-'; break;
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|     case MCBinaryExpr::Xor:  OS <<  '^'; break;
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|     }
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| 
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|     // Only print parens around the LHS if it is non-trivial.
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|     if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
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|       OS << *BE.getRHS();
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|     } else {
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|       OS << '(' << *BE.getRHS() << ')';
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|     }
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|     return;
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|   }
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|   }
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| 
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|   assert(0 && "Invalid expression kind!");
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| }
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| 
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| void MCExpr::dump() const {
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|   print(dbgs());
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|   dbgs() << '\n';
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| }
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| 
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| /* *** */
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| 
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| const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS,
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|                                          const MCExpr *RHS, MCContext &Ctx) {
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|   return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
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| }
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| 
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| const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
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|                                        MCContext &Ctx) {
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|   return new (Ctx) MCUnaryExpr(Opc, Expr);
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| }
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| 
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| const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
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|   return new (Ctx) MCConstantExpr(Value);
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| }
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| 
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| /* *** */
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| 
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| const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
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|                                                VariantKind Kind,
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|                                                MCContext &Ctx) {
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|   return new (Ctx) MCSymbolRefExpr(Sym, Kind);
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| }
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| 
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| const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
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|                                                MCContext &Ctx) {
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|   return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
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| }
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| 
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| StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
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|   switch (Kind) {
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|   default:
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|   case VK_Invalid: return "<<invalid>>";
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|   case VK_None: return "<<none>>";
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| 
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|   case VK_GOT: return "GOT";
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|   case VK_GOTOFF: return "GOTOFF";
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|   case VK_GOTPCREL: return "GOTPCREL";
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|   case VK_GOTTPOFF: return "GOTTPOFF";
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|   case VK_INDNTPOFF: return "INDNTPOFF";
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|   case VK_NTPOFF: return "NTPOFF";
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|   case VK_PLT: return "PLT";
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|   case VK_TLSGD: return "TLSGD";
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|   case VK_TPOFF: return "TPOFF";
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|   case VK_ARM_HI16: return ":upper16:";
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|   case VK_ARM_LO16: return ":lower16:";
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|   case VK_TLVP: return "TLVP";
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|   }
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| }
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| 
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| MCSymbolRefExpr::VariantKind
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| MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
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|   return StringSwitch<VariantKind>(Name)
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|     .Case("GOT", VK_GOT)
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|     .Case("GOTOFF", VK_GOTOFF)
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|     .Case("GOTPCREL", VK_GOTPCREL)
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|     .Case("GOTTPOFF", VK_GOTTPOFF)
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|     .Case("INDNTPOFF", VK_INDNTPOFF)
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|     .Case("NTPOFF", VK_NTPOFF)
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|     .Case("PLT", VK_PLT)
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|     .Case("TLSGD", VK_TLSGD)
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|     .Case("TPOFF", VK_TPOFF)
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|     .Case("TLVP", VK_TLVP)
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|     .Default(VK_Invalid);
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| }
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| 
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| /* *** */
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| 
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| void MCTargetExpr::Anchor() {}
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| 
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| /* *** */
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| 
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| bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout *Layout) const {
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|   MCValue Value;
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| 
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|   // Fast path constants.
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|   if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
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|     Res = CE->getValue();
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|     return true;
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|   }
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| 
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|   if (!EvaluateAsRelocatable(Value, Layout) || !Value.isAbsolute())
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|     return false;
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| 
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|   Res = Value.getConstant();
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|   return true;
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| }
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| 
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| static bool EvaluateSymbolicAdd(const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
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|                                 const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
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|                                 MCValue &Res) {
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|   // We can't add or subtract two symbols.
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|   if ((LHS.getSymA() && RHS_A) ||
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|       (LHS.getSymB() && RHS_B))
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|     return false;
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| 
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|   const MCSymbolRefExpr *A = LHS.getSymA() ? LHS.getSymA() : RHS_A;
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|   const MCSymbolRefExpr *B = LHS.getSymB() ? LHS.getSymB() : RHS_B;
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|   if (B) {
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|     // If we have a negated symbol, then we must have also have a non-negated
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|     // symbol in order to encode the expression. We can do this check later to
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|     // permit expressions which eventually fold to a representable form -- such
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|     // as (a + (0 - b)) -- if necessary.
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|     if (!A)
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|       return false;
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|   }
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|   Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst);
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|   return true;
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| }
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| 
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| bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
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|                                    const MCAsmLayout *Layout) const {
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|   ++stats::MCExprEvaluate;
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| 
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|   switch (getKind()) {
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|   case Target:
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|     return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
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| 
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|   case Constant:
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|     Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
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|     return true;
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| 
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|   case SymbolRef: {
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|     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
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|     const MCSymbol &Sym = SRE->getSymbol();
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| 
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|     // Evaluate recursively if this is a variable.
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|     if (Sym.isVariable()) {
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|       if (!Sym.getVariableValue()->EvaluateAsRelocatable(Res, Layout))
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|         return false;
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| 
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|       // Absolutize symbol differences between defined symbols when we have a
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|       // layout object and the target requests it.
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|       if (Layout && Res.getSymB() &&
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|           Layout->getAssembler().getBackend().hasAbsolutizedSet() &&
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|           Res.getSymA()->getSymbol().isDefined() &&
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|           Res.getSymB()->getSymbol().isDefined()) {
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|         MCSymbolData &A =
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|           Layout->getAssembler().getSymbolData(Res.getSymA()->getSymbol());
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|         MCSymbolData &B =
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|           Layout->getAssembler().getSymbolData(Res.getSymB()->getSymbol());
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|         Res = MCValue::get(+ Layout->getSymbolAddress(&A)
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|                            - Layout->getSymbolAddress(&B)
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|                            + Res.getConstant());
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|       }
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| 
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|       return true;
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|     }
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| 
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|     Res = MCValue::get(SRE, 0, 0);
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|     return true;
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|   }
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| 
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|   case Unary: {
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|     const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
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|     MCValue Value;
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| 
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|     if (!AUE->getSubExpr()->EvaluateAsRelocatable(Value, Layout))
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|       return false;
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| 
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|     switch (AUE->getOpcode()) {
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|     case MCUnaryExpr::LNot:
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|       if (!Value.isAbsolute())
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|         return false;
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|       Res = MCValue::get(!Value.getConstant());
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|       break;
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|     case MCUnaryExpr::Minus:
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|       /// -(a - b + const) ==> (b - a - const)
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|       if (Value.getSymA() && !Value.getSymB())
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|         return false;
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|       Res = MCValue::get(Value.getSymB(), Value.getSymA(),
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|                          -Value.getConstant());
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|       break;
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|     case MCUnaryExpr::Not:
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|       if (!Value.isAbsolute())
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|         return false;
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|       Res = MCValue::get(~Value.getConstant());
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|       break;
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|     case MCUnaryExpr::Plus:
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|       Res = Value;
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|       break;
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|     }
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| 
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|     return true;
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|   }
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| 
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|   case Binary: {
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|     const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
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|     MCValue LHSValue, RHSValue;
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| 
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|     if (!ABE->getLHS()->EvaluateAsRelocatable(LHSValue, Layout) ||
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|         !ABE->getRHS()->EvaluateAsRelocatable(RHSValue, Layout))
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|       return false;
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| 
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|     // We only support a few operations on non-constant expressions, handle
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|     // those first.
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|     if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
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|       switch (ABE->getOpcode()) {
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|       default:
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|         return false;
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|       case MCBinaryExpr::Sub:
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|         // Negate RHS and add.
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|         return EvaluateSymbolicAdd(LHSValue,
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|                                    RHSValue.getSymB(), RHSValue.getSymA(),
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|                                    -RHSValue.getConstant(),
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|                                    Res);
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| 
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|       case MCBinaryExpr::Add:
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|         return EvaluateSymbolicAdd(LHSValue,
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|                                    RHSValue.getSymA(), RHSValue.getSymB(),
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|                                    RHSValue.getConstant(),
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|                                    Res);
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|       }
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|     }
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| 
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|     // FIXME: We need target hooks for the evaluation. It may be limited in
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|     // width, and gas defines the result of comparisons and right shifts
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|     // differently from Apple as.
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|     int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
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|     int64_t Result = 0;
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|     switch (ABE->getOpcode()) {
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|     case MCBinaryExpr::Add:  Result = LHS + RHS; break;
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|     case MCBinaryExpr::And:  Result = LHS & RHS; break;
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|     case MCBinaryExpr::Div:  Result = LHS / RHS; break;
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|     case MCBinaryExpr::EQ:   Result = LHS == RHS; break;
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|     case MCBinaryExpr::GT:   Result = LHS > RHS; break;
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|     case MCBinaryExpr::GTE:  Result = LHS >= RHS; break;
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|     case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
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|     case MCBinaryExpr::LOr:  Result = LHS || RHS; break;
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|     case MCBinaryExpr::LT:   Result = LHS < RHS; break;
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|     case MCBinaryExpr::LTE:  Result = LHS <= RHS; break;
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|     case MCBinaryExpr::Mod:  Result = LHS % RHS; break;
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|     case MCBinaryExpr::Mul:  Result = LHS * RHS; break;
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|     case MCBinaryExpr::NE:   Result = LHS != RHS; break;
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|     case MCBinaryExpr::Or:   Result = LHS | RHS; break;
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|     case MCBinaryExpr::Shl:  Result = LHS << RHS; break;
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|     case MCBinaryExpr::Shr:  Result = LHS >> RHS; break;
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|     case MCBinaryExpr::Sub:  Result = LHS - RHS; break;
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|     case MCBinaryExpr::Xor:  Result = LHS ^ RHS; break;
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|     }
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| 
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|     Res = MCValue::get(Result);
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|     return true;
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|   }
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|   }
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| 
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|   assert(0 && "Invalid assembly expression kind!");
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|   return false;
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| }
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