Subzero: Improve x86-32's implementation of getGprForType().

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 2551 matching lines @@
     case IceType_i1:
     case IceType_i8:
     case IceType_i16:
       llvm::report_fatal_error("Invalid Call dest type");
       break;
     case IceType_i32:
       ReturnReg = makeReg(DestTy, Traits::RegisterSet::Reg_eax);
       break;
     case IceType_i64:
       if (Traits::Is64Bit) {
-        ReturnReg = makeReg(
-            IceType_i64,
-            Traits::getGprForType(IceType_i64, Traits::RegisterSet::Reg_eax));
+        ReturnReg = makeReg(IceType_i64, Traits::getRaxOrDie());
       } else {
         ReturnReg = makeReg(IceType_i32, Traits::RegisterSet::Reg_eax);
         ReturnRegHi = makeReg(IceType_i32, Traits::RegisterSet::Reg_edx);
       }
       break;
     case IceType_f32:
     case IceType_f64:
       if (!Traits::X86_PASS_SCALAR_FP_IN_XMM) {
         // Leave ReturnReg==ReturnRegHi==nullptr, and capture the result with
         // the fstp instruction.
@@ skipping 4872 matching lines @@
         emitGlobal(*Var, SectionSuffix);
       }
     }
   } break;
   }
 }
 } // end of namespace X86NAMESPACE
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASEIMPL_H