[x86] Additional small fix for MCU psABI support

[andreybokhanko]

Summary

This patch fixes one more thing in MCU psABI support: LongDoubleWidth should be set to 64.

[rnk]

lgtm

cfe/trunk/lib/Basic/Targets.cpp

enum FPMathKind {
     FP_Default,
     FP_SSE,
     FP_387
   } FPMath = FP_Default;
 
 public:
   X86TargetInfo(const llvm::Triple &Triple) : TargetInfo(Triple) {
     BigEndian = false;
-    LongDoubleFormat = Triple.isOSIAMCU() ? &llvm::APFloat::IEEEdouble
-                                          : &llvm::APFloat::x87DoubleExtended;
+    LongDoubleFormat = &llvm::APFloat::x87DoubleExtended;
   }
   unsigned getFloatEvalMethod() const override {
     // X87 evaluates with 80 bits "long double" precision.
     return SSELevel == NoSSE ? 2 : 0;
   }
   ArrayRef<Builtin::Info> getTargetBuiltins() const override {
     return llvm::makeArrayRef(BuiltinInfo,
                              clang::X86::LastTSBuiltin-Builtin::FirstTSBuiltin);
X86_32TargetInfo(const llvm::Triple &Triple) : X86TargetInfo(Triple) {
     LongDoubleAlign = 32;
     SuitableAlign = 128;
     DataLayoutString = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128";
     SizeType = UnsignedInt;
     PtrDiffType = SignedInt;
     IntPtrType = SignedInt;
     RegParmMax = 3;
 
+    if (getTriple().isOSIAMCU()) {
+      LongDoubleWidth = 64;
+      LongDoubleFormat = &llvm::APFloat::IEEEdouble;
+    }
+
     // Use fpret for all types.
     RealTypeUsesObjCFPRet = ((1 << TargetInfo::Float) |
                              (1 << TargetInfo::Double) |
                              (1 << TargetInfo::LongDouble));
 
     // x86-32 has atomics up to 8 bytes
     // FIXME: Check that we actually have cmpxchg8b before setting
     // MaxAtomicInlineWidth. (cmpxchg8b is an i586 instruction.)

cfe/trunk/test/CodeGen/x86_32-arguments-iamcu.c

 st12_t retLargeStruct(int i1, st12_t r) { return r; }
 
 // FIXME: We really shouldn't be marking this inreg. Right now the
 // inreg gets ignored by the CG for varargs functions, but that's
 // insane.
 // CHECK-LABEL: define i32 @varArgs(i32 inreg %i1, ...)
 int varArgs(int i1, ...) { return i1; }
 
-// CHECK-LABEL: define double @longDoubleArg(double %ld1)
+// CHECK-LABEL: define double @longDoubleArg(double inreg %ld1)
 long double longDoubleArg(long double ld1) { return ld1; }