Subzero: Randomly insert nops.

src/IceInstX8632.cpp

 //===- subzero/src/IceInstX8632.cpp - X86-32 instruction implementation ---===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the InstX8632 and OperandX8632 classes,
@@ skipping 238 matching lines @@
 InstX8632Movsx::InstX8632Movsx(Cfg *Func, Variable *Dest, Operand *Source)
     : InstX8632(Func, InstX8632::Movsx, 1, Dest) {
   addSource(Source);
 }
 
 InstX8632Movzx::InstX8632Movzx(Cfg *Func, Variable *Dest, Operand *Source)
     : InstX8632(Func, InstX8632::Movzx, 1, Dest) {
   addSource(Source);
 }
 
+InstX8632Nop::InstX8632Nop(Cfg *Func, SizeT Length)
+    : InstX8632(Func, InstX8632::Nop, 0, NULL), Length(Length) {}
+
 InstX8632Fld::InstX8632Fld(Cfg *Func, Operand *Src)
     : InstX8632(Func, InstX8632::Fld, 1, NULL) {
   addSource(Src);
 }
 
 InstX8632Fstp::InstX8632Fstp(Cfg *Func, Variable *Dest)
     : InstX8632(Func, InstX8632::Fstp, 0, Dest) {}
 
 InstX8632Pop::InstX8632Pop(Cfg *Func, Variable *Dest)
     : InstX8632(Func, InstX8632::Pop, 0, Dest) {}
@@ skipping 847 matching lines @@
 
 void InstX8632Movzx::dump(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrDump();
   Str << "movzx." << getDest()->getType() << "." << getSrc(0)->getType();
   Str << " ";
   dumpDest(Func);
   Str << ", ";
   dumpSources(Func);
 }
 
+void InstX8632Nop::emit(const Cfg *Func) const {
+  Ostream &Str = Func->getContext()->getStrEmit();
+  assert(Length);
+  // TODO: When an assembler is used, use the recommended opcodes in the
+  // Intel manual to emit nop instructions based on the length.
+  Str << "\tnop\t# length = " << Length << (Length > 1 ? " bytes" : " byte")
+      << "\n";
+}
+
+void InstX8632Nop::dump(const Cfg *Func) const {
+  Ostream &Str = Func->getContext()->getStrDump();
+  Str << "nop (length = " << Length << (Length > 1 ? " bytes)" : " byte)");
+}
+
 void InstX8632Fld::emit(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrEmit();
   assert(getSrcSize() == 1);
   Type Ty = getSrc(0)->getType();
   Variable *Var = llvm::dyn_cast<Variable>(getSrc(0));
   if (Var && Var->hasReg()) {
     // This is a physical xmm register, so we need to spill it to a
     // temporary stack slot.
     SizeT Width = typeWidthInBytes(Ty);
     Str << "\tsub\tesp, " << Width << "\n";
@@ skipping 374 matching lines @@
   default:
     Str << "???";
     break;
   }
   Str << "(";
   Var->dump(Func);
   Str << ")";
 }
 
 } // end of namespace Ice