Subzero: Improve lowering of rematerializable call args.

src/IceTargetLoweringX86BaseImpl.h

 //===- subzero/src/IceTargetLoweringX86BaseImpl.h - x86 lowering -*- C++ -*-==//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 2600 matching lines @@
         InstStore::create(Func, legalize(StackArgs[i]), StackArgLocations[i]));
   }
   // Copy arguments to be passed in registers to the appropriate registers.
   for (SizeT i = 0, NumXmmArgs = XmmArgs.size(); i < NumXmmArgs; ++i) {
     XmmArgs[i] =
         legalizeToReg(legalize(XmmArgs[i]), Traits::getRegisterForXmmArgNum(i));
   }
   // Materialize moves for arguments passed in GPRs.
   for (SizeT i = 0, NumGprArgs = GprArgs.size(); i < NumGprArgs; ++i) {
     const Type SignatureTy = GprArgs[i].first;
-    Operand *Arg = legalize(GprArgs[i].second);
+    Operand *Arg =
+        legalize(GprArgs[i].second, Legal_Default | Legal_Rematerializable);
     GprArgs[i].second =
         legalizeToReg(Arg, Traits::getRegisterForGprArgNum(Arg->getType(), i));
     assert(SignatureTy == IceType_i64 || SignatureTy == IceType_i32);
     assert(SignatureTy == Arg->getType());
     (void)SignatureTy;
   }
   // Generate a FakeUse of register arguments so that they do not get dead code
   // eliminated as a result of the FakeKill of scratch registers after the call.
   // These need to be right before the call instruction.
   for (auto *Arg : XmmArgs) {
@@ skipping 5334 matching lines @@
         emitGlobal(*Var, SectionSuffix);
       }
     }
   } break;
   }
 }
 } // end of namespace X86NAMESPACE
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASEIMPL_H