[mips] Kill 'support' for untested EABI.

[dsanders]

Summary

There are no clang or llvm* tests for EABI and no EABI buildbots.

*There is a single backend test that specifies EABI but it tests MIPS16.

Depends on D20678

[atanasyan]

LGTM

Tools.cpp contains the following code. We need to remove eabi here too.

if (CPUName.empty()) {
  // Deduce CPU name from ABI name.
  CPUName = llvm::StringSwitch<const char *>(ABIName)
                .Cases("o32", "eabi", DefMips32CPU)
                .Cases("n32", "n64", DefMips64CPU)
                .Default("");
}

[dsanders]

Removed the 'eabi' from Tools.cpp this revealed three driver tests for passing
-mabi to the assembler but the ABI itself is still completely untested.

[dsanders]

Just to double-check: Do you still agree we should kill this now that the number of tests covering EABI-specific behaviour is non-zero?

I think we should on the basis that we still have no backend tests and no buildbots. The only tests we have check that the driver passes -mabi=eabi to the assembler.

[atanasyan]

In D20679#442121, @dsanders wrote:

Just to double-check: Do you still agree we should kill this now that the number of tests covering EABI-specific behaviour is non-zero?

I think we should on the basis that we still have no backend tests and no buildbots. The only tests we have check that the driver passes -mabi=eabi to the assembler.

I agree.

lib/Basic/Targets.cpp

public:
   ArrayRef<TargetInfo::GCCRegAlias> getGCCRegAliases() const override {
     return None;
   }
 };
 
 class MipsTargetInfo : public TargetInfo {
   void setDataLayout() {
     if (BigEndian) {
-      if (ABI == "o32" || ABI == "eabi")
+      if (ABI == "o32")
         resetDataLayout("E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64");
       else if (ABI == "n32")
         resetDataLayout("E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32:64-S128");
       else if (ABI == "n64")
         resetDataLayout("E-m:m-i8:8:32-i16:16:32-i64:64-n32:64-S128");
       else
         llvm_unreachable("Invalid ABI");
     } else {
-      if (ABI == "o32" || ABI == "eabi")
+      if (ABI == "o32")
         resetDataLayout("e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64");
       else if (ABI == "n32")
         resetDataLayout("e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32:64-S128");
       else if (ABI == "n64")
         resetDataLayout("e-m:m-i8:8:32-i16:16:32-i64:64-n32:64-S128");
       else
         llvm_unreachable("Invalid ABI");
     }
public:
   bool isNan2008() const override {
     return IsNan2008;
   }
 
   StringRef getABI() const override { return ABI; }
   bool setABI(const std::string &Name) override {
     if (getTriple().getArch() == llvm::Triple::mips ||
         getTriple().getArch() == llvm::Triple::mipsel) {
-      if (Name == "o32" || Name == "eabi") {
+      if (Name == "o32") {
         ABI = Name;
         return true;
       }
     }
     if (getTriple().getArch() == llvm::Triple::mips64 ||
         getTriple().getArch() == llvm::Triple::mips64el) {
       if (Name == "n32") {
         setN32ABITypes();
const std::string ISARev = llvm::StringSwitch<std::string>(getCPU())
                                    .Default("");
     if (!ISARev.empty())
       Builder.defineMacro("__mips_isa_rev", ISARev);
 
     if (ABI == "o32") {
       Builder.defineMacro("__mips_o32");
       Builder.defineMacro("_ABIO32", "1");
       Builder.defineMacro("_MIPS_SIM", "_ABIO32");
-    } else if (ABI == "eabi")
-      Builder.defineMacro("__mips_eabi");
-    else if (ABI == "n32") {
+    } else if (ABI == "n32") {
       Builder.defineMacro("__mips_n32");
       Builder.defineMacro("_ABIN32", "2");
       Builder.defineMacro("_MIPS_SIM", "_ABIN32");
     } else if (ABI == "n64") {
       Builder.defineMacro("__mips_n64");
       Builder.defineMacro("_ABI64", "3");
       Builder.defineMacro("_MIPS_SIM", "_ABI64");
     } else