Remove floating point related target defaults. Add comments.

Author: Prabhuk

clang/lib/Basic/Targets/X86.h

@@ -835,20 +835,30 @@ class LLVM_LIBRARY_VISIBILITY UEFIX86_64TargetInfo
 public:
   UEFIX86_64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : UEFITargetInfo<X86_64TargetInfo>(Triple, Opts) {
-    LongWidth = LongAlign = 32;
-    DoubleAlign = LongLongAlign = 64;
+    this->setABIDefaults();
+    this->resetDataLayout("e-m:w-p270:32:32-p271:32:32-p272:64:64-"
+                          "i64:64-i128:128-f80:128-n8:16:32:64-S128");
+  }
+
+  // The UEFI spec does not mandate specific C++ ABI, integer widths, or
+  // alignment. We are setting these defaults to match the Windows target as it
+  // is the only way to build EFI applications with Clang/LLVM today. We intend
+  // to offer flexibility by supporting choices that are not default in Windows
+  // target in the future.
+  void setABIDefaults() {
+    // Set C++ ABI.
+    this->TheCXXABI.set(TargetCXXABI::Microsoft);
+    // Set Integer types and alignment.
     IntMaxType = SignedLongLong;
     Int64Type = SignedLongLong;
     SizeType = UnsignedLongLong;
     PtrDiffType = SignedLongLong;
     IntPtrType = SignedLongLong;
-    LongDoubleWidth = LongDoubleAlign = 64;
-    LongDoubleFormat = &llvm::APFloat::IEEEdouble();
     WCharType = UnsignedShort;
     WIntType = UnsignedShort;
-    this->TheCXXABI.set(TargetCXXABI::Microsoft);
-    this->resetDataLayout("e-m:w-p270:32:32-p271:32:32-p272:64:64-"
-                          "i64:64-i128:128-f80:128-n8:16:32:64-S128");
+    LongWidth = LongAlign = 32;
+    DoubleAlign = LongLongAlign = 64;
+    LongDoubleWidth = LongDoubleAlign = 64;
   }
 
   CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {