[clang] [clang] Fix UEFI Target info (PR #127290)

[Petr Hosek via cfe-commits]

================
@@ -835,8 +835,24 @@ class LLVM_LIBRARY_VISIBILITY UEFIX86_64TargetInfo
 public:
   UEFIX86_64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : UEFITargetInfo<X86_64TargetInfo>(Triple, Opts) {
+    // 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.
+
+    // Set C++ ABI.
     this->TheCXXABI.set(TargetCXXABI::Microsoft);
-    this->MaxTLSAlign = 8192u * this->getCharWidth();
+    // Set Integer types and alignment.
+    IntMaxType = SignedLongLong;
+    Int64Type = SignedLongLong;
+    SizeType = UnsignedLongLong;
+    PtrDiffType = SignedLongLong;
+    IntPtrType = SignedLongLong;
+    WCharType = UnsignedShort;
+    WIntType = UnsignedShort;
+    LongWidth = LongAlign = 32;
----------------
petrhosek wrote:

Looks like UEFI supports float so we should include it here.
```suggestion
    LongWidth = LongAlign = 32;
    DoubleAlign = LongLongAlign = 64;
    LongDoubleWidth = LongDoubleAlign = 64;
    LongDoubleFormat = &llvm::APFloat::IEEEdouble();
    IntMaxType = SignedLongLong;
    Int64Type = SignedLongLong;
    SizeType = UnsignedLongLong;
    PtrDiffType = SignedLongLong;
    IntPtrType = SignedLongLong;
    WCharType = UnsignedShort;
    WIntType = UnsignedShort;
```

https://github.com/llvm/llvm-project/pull/127290