Simplify field names and remove unnecessary routine

Perform the following cleanup:
- Rename explicitLinkageType to linkageType
- Add enum entries in OMR and remove magic constant
- Remove isOSLinkageType routine

Signed-off-by: Dhruv Chopra <Dhruv.C.Chopra@ibm.com>

compiler/codegen/OMRLinkageConventions.enum

@@ -29,3 +29,11 @@
    TR_System,
    TR_Helper,
    TR_J9JNILinkage,
+   TR_SystemXPLink,                     // zOS XPLink convention
+
+   // zOS Type 1 linkages - all have bit 0x40 set
+   // zOS Type 1 linkage - C++ Fastlink
+   TR_SystemFastLink,                   // zOS (C++) FastLink convention
+
+   // Linux Platform Linkages
+   TR_SystemLinux,//          = 60     // zLinux convention

compiler/z/codegen/OMRLinkage.cpp

@@ -102,7 +102,7 @@ extern bool storeHelperImmediateInstruction(TR::Node * valueChild, TR::CodeGener
 
 OMR::Z::Linkage::Linkage(TR::CodeGenerator * codeGen)
    : OMR::Linkage(codeGen),
-      _explicitLinkageType(TR_None), _stackSizeCheckNeeded(true), _raContextSaveNeeded(true),
+      _linkageType(TR_None), _stackSizeCheckNeeded(true), _raContextSaveNeeded(true),
       _integerReturnRegister(TR::RealRegister::NoReg),
       _floatReturnRegister(TR::RealRegister::NoReg),
       _doubleReturnRegister(TR::RealRegister::NoReg),
@@ -135,9 +135,9 @@ OMR::Z::Linkage::Linkage(TR::CodeGenerator * codeGen)
  * convention.
  * Even though this method is common, its implementation is machine-specific.
  */
-OMR::Z::Linkage::Linkage(TR::CodeGenerator * codeGen,TR_LinkageConventions elc)
+OMR::Z::Linkage::Linkage(TR::CodeGenerator * codeGen,TR_LinkageConventions lc)
    : OMR::Linkage(codeGen),
-      _explicitLinkageType(elc), _stackSizeCheckNeeded(true), _raContextSaveNeeded(true),
+      _linkageType(lc), _stackSizeCheckNeeded(true), _raContextSaveNeeded(true),
       _integerReturnRegister(TR::RealRegister::NoReg),
       _floatReturnRegister(TR::RealRegister::NoReg),
       _doubleReturnRegister(TR::RealRegister::NoReg),
@@ -2837,30 +2837,22 @@ OMR::Z::Linkage::getLastMaskedBit(int16_t mask)
    return TR::Linkage::getLastMaskedBit(mask , 0, 15);
    }
 
-bool
-OMR::Z::Linkage::isOSLinkageType()
-   {
-   // #define TR_SystemOS_MASK  0x40
-   // zOS Type 1 linkages (non-Java) - all have bit 0x40 set
-   return (self()->getExplicitLinkageType() & 0x40) != 0;
-   }
-
 bool
 OMR::Z::Linkage::isXPLinkLinkageType()
    {
-   return self()->getExplicitLinkageType() == TR_SystemXPLink;
+   return self()->getLinkageType() == TR_SystemXPLink;
    }
 
 bool
 OMR::Z::Linkage::isFastLinkLinkageType()
    {
-   return self()->getExplicitLinkageType() == TR_SystemFastLink;
+   return self()->getLinkageType() == TR_SystemFastLink;
    }
 
 bool
 OMR::Z::Linkage::isZLinuxLinkageType()
    {
-   return self()->getExplicitLinkageType() == TR_SystemLinux;
+   return self()->getLinkageType() == TR_SystemLinux;
    }
 
 TR::Register *

compiler/z/codegen/OMRLinkage.hpp

@@ -172,7 +172,7 @@ namespace Z
 class OMR_EXTENSIBLE Linkage : public OMR::Linkage
    {
 private:
-   TR_LinkageConventions _explicitLinkageType;
+   TR_LinkageConventions _linkageType;
    uint32_t _properties;
    uint32_t _registerFlags[TR::RealRegister::NumRegisters];
    uint8_t _numIntegerArgumentRegisters;
@@ -235,10 +235,9 @@ enum TR_DispatchType
 
    Linkage(TR::CodeGenerator *, TR_LinkageConventions);
 
-   TR_LinkageConventions getExplicitLinkageType() { return _explicitLinkageType; }
-   void setExplicitLinkageType(TR_LinkageConventions lc ) { _explicitLinkageType = lc; }
+   TR_LinkageConventions getLinkageType() { return _linkageType; }
+   void setLinkageType(TR_LinkageConventions lc ) { _linkageType = lc; }
 
-   bool isOSLinkageType();
    bool isXPLinkLinkageType();
    bool isFastLinkLinkageType();
 

compiler/z/codegen/SystemLinkage.cpp

@@ -296,7 +296,7 @@ TR::SystemLinkage::mapStack(TR::ResolvedMethodSymbol * method, uint32_t stackInd
 
       setFPRSaveMask(FPRSaveMask);
 
-      if (FPRSaveMask != 0 && isOSLinkageType())
+      if (FPRSaveMask != 0)
          {
          #define DELTA_ALIGN(x, align) ((x & (align-1)) ? (align -((x)&(align-1))) : 0)
          stackIndex -= DELTA_ALIGN(stackIndex, 16);