SystemZ: Migrate to newer relocation specifier representation

z/OS creates SystemZMCExpr objects (https://reviews.llvm.org/D153788)
while ELF doesn't. Define the SystemZMCAsmInfoGOFF hooks
instead of the legacy MCSpecifierExpr:: hooks.

Author: MaskRay

llvm/lib/Target/SystemZ/AsmParser/SystemZAsmParser.cpp

@@ -8,7 +8,6 @@
 
 #include "MCTargetDesc/SystemZGNUInstPrinter.h"
 #include "MCTargetDesc/SystemZMCAsmInfo.h"
-#include "MCTargetDesc/SystemZMCExpr.h"
 #include "MCTargetDesc/SystemZMCTargetDesc.h"
 #include "MCTargetDesc/SystemZTargetStreamer.h"
 #include "TargetInfo/SystemZTargetInfo.h"
@@ -1707,7 +1706,7 @@ ParseStatus SystemZAsmParser::parsePCRel(OperandVector &Operands,
     if (Parser.getTok().isNot(AsmToken::Identifier))
       return Error(Parser.getTok().getLoc(), "unexpected token");
 
-    SystemZMCExpr::Specifier Kind = SystemZ::S_None;
+    auto Kind = SystemZ::S_None;
     StringRef Name = Parser.getTok().getString();
     if (Name == "tls_gdcall")
       Kind = SystemZ::S_TLSGD;

llvm/lib/Target/SystemZ/MCTargetDesc/CMakeLists.txt

@@ -8,7 +8,6 @@ add_llvm_component_library(LLVMSystemZDesc
   SystemZMCAsmBackend.cpp
   SystemZMCAsmInfo.cpp
   SystemZMCCodeEmitter.cpp
-  SystemZMCExpr.cpp
   SystemZMCTargetDesc.cpp
   SystemZTargetStreamer.cpp
 

llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCAsmInfo.cpp

@@ -7,9 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "SystemZMCAsmInfo.h"
-#include "MCTargetDesc/SystemZMCExpr.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
 
 using namespace llvm;
 
@@ -58,3 +58,31 @@ SystemZMCAsmInfoGOFF::SystemZMCAsmInfoGOFF(const Triple &TT) {
 bool SystemZMCAsmInfoGOFF::isAcceptableChar(char C) const {
   return MCAsmInfo::isAcceptableChar(C) || C == '#';
 }
+
+void SystemZMCAsmInfoGOFF::printSpecifierExpr(
+    raw_ostream &OS, const MCSpecifierExpr &Expr) const {
+  switch (Expr.getSpecifier()) {
+  case SystemZ::S_None:
+    OS << "A";
+    break;
+  case SystemZ::S_RCon:
+    OS << "R";
+    break;
+  case SystemZ::S_VCon:
+    OS << "V";
+    break;
+  default:
+    llvm_unreachable("Invalid kind");
+  }
+  OS << '(';
+  printExpr(OS, *Expr.getSubExpr());
+  OS << ')';
+}
+
+bool SystemZMCAsmInfoGOFF::evaluateAsRelocatableImpl(
+    const MCSpecifierExpr &Expr, MCValue &Res, const MCAssembler *Asm) const {
+  if (!Expr.getSubExpr()->evaluateAsRelocatable(Res, Asm))
+    return false;
+  Res.setSpecifier(Expr.getSpecifier());
+  return true;
+}

llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCAsmInfo.h

@@ -26,6 +26,10 @@ class SystemZMCAsmInfoGOFF : public MCAsmInfoGOFF {
 public:
   explicit SystemZMCAsmInfoGOFF(const Triple &TT);
   bool isAcceptableChar(char C) const override;
+  void printSpecifierExpr(raw_ostream &OS,
+                          const MCSpecifierExpr &Expr) const override;
+  bool evaluateAsRelocatableImpl(const MCSpecifierExpr &Expr, MCValue &Res,
+                                 const MCAssembler *Asm) const override;
 };
 
 namespace SystemZ {

llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCExpr.cpp

@@ -1139,23 +1139,20 @@ void SystemZAsmPrinter::emitADASection() {
       // imported functions, that are placed in the ADA to be 8 byte aligned.
       EMIT_COMMENT("function descriptor of");
       OutStreamer->emitValue(
-          SystemZMCExpr::create(SystemZ::S_RCon,
-                                MCSymbolRefExpr::create(Sym, OutContext),
-                                OutContext),
+          MCSpecifierExpr::create(MCSymbolRefExpr::create(Sym, OutContext),
+                                  SystemZ::S_RCon, OutContext),
           PointerSize);
       OutStreamer->emitValue(
-          SystemZMCExpr::create(SystemZ::S_VCon,
-                                MCSymbolRefExpr::create(Sym, OutContext),
-                                OutContext),
+          MCSpecifierExpr::create(MCSymbolRefExpr::create(Sym, OutContext),
+                                  SystemZ::S_VCon, OutContext),
           PointerSize);
       EmittedBytes += PointerSize * 2;
       break;
     case SystemZII::MO_ADA_DATA_SYMBOL_ADDR:
       EMIT_COMMENT("pointer to data symbol");
       OutStreamer->emitValue(
-          SystemZMCExpr::create(SystemZ::S_None,
-                                MCSymbolRefExpr::create(Sym, OutContext),
-                                OutContext),
+          MCSpecifierExpr::create(MCSymbolRefExpr::create(Sym, OutContext),
+                                  SystemZ::S_None, OutContext),
           PointerSize);
       EmittedBytes += PointerSize;
       break;
@@ -1168,9 +1165,8 @@ void SystemZAsmPrinter::emitADASection() {
 
       EMIT_COMMENT("pointer to function descriptor");
       OutStreamer->emitValue(
-          SystemZMCExpr::create(SystemZ::S_VCon,
-                                MCSymbolRefExpr::create(Alias, OutContext),
-                                OutContext),
+          MCSpecifierExpr::create(MCSymbolRefExpr::create(Alias, OutContext),
+                                  SystemZ::S_VCon, OutContext),
           PointerSize);
       EmittedBytes += PointerSize;
       break;

llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCExpr.h

@@ -16,8 +16,8 @@
 
 using namespace llvm;
 
-// Return the VK_* enumeration for MachineOperand target flags Flags.
-static SystemZMCExpr::Specifier getSpecifierForTFlags(unsigned Flags) {
+// Return the S_* enumeration for MachineOperand target flags Flags.
+static SystemZ::Specifier getSpecifierForTFlags(unsigned Flags) {
   switch (Flags & SystemZII::MO_SYMBOL_MODIFIER) {
     case 0:
       return SystemZ::S_None;
@@ -34,7 +34,7 @@ SystemZMCInstLower::SystemZMCInstLower(MCContext &ctx,
   : Ctx(ctx), AsmPrinter(asmprinter) {}
 
 const MCExpr *SystemZMCInstLower::getExpr(const MachineOperand &MO,
-                                          SystemZMCExpr::Specifier Spec) const {
+                                          SystemZ::Specifier Spec) const {
   const MCSymbol *Symbol;
   bool HasOffset = true;
   switch (MO.getType()) {
@@ -85,7 +85,7 @@ MCOperand SystemZMCInstLower::lowerOperand(const MachineOperand &MO) const {
     return MCOperand::createImm(MO.getImm());
 
   default: {
-    SystemZMCExpr::Specifier Kind = getSpecifierForTFlags(MO.getTargetFlags());
+    auto Kind = getSpecifierForTFlags(MO.getTargetFlags());
     return MCOperand::createExpr(getExpr(MO, Kind));
   }
   }

llvm/lib/Target/SystemZ/SystemZAsmPrinter.cpp

@@ -9,7 +9,7 @@
 #ifndef LLVM_LIB_TARGET_SYSTEMZ_SYSTEMZMCINSTLOWER_H
 #define LLVM_LIB_TARGET_SYSTEMZ_SYSTEMZMCINSTLOWER_H
 
-#include "MCTargetDesc/SystemZMCExpr.h"
+#include "MCTargetDesc/SystemZMCAsmInfo.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
@@ -35,8 +35,7 @@ class LLVM_LIBRARY_VISIBILITY SystemZMCInstLower {
   MCOperand lowerOperand(const MachineOperand& MO) const;
 
   // Return an MCExpr for symbolic operand MO with variant kind Kind.
-  const MCExpr *getExpr(const MachineOperand &MO,
-                        SystemZMCExpr::Specifier) const;
+  const MCExpr *getExpr(const MachineOperand &MO, SystemZ::Specifier) const;
 };
 } // end namespace llvm