Revert r302670 for the upcoming 5.0.0 release

This is causing failures when compiling clang with -O3
as one of the structures used by clang is passed by
value and uses the fastcc calling convention.

Faliures manifest for stage2 mips build.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310704 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/TargetInfo.cpp

@@ -6821,14 +6821,6 @@ MipsABIInfo::classifyArgumentType(QualType Ty, uint64_t &Offset) const {
       return getNaturalAlignIndirect(Ty, RAA == CGCXXABI::RAA_DirectInMemory);
     }
 
-    // Use indirect if the aggregate cannot fit into registers for
-    // passing arguments according to the ABI
-    unsigned Threshold = IsO32 ? 16 : 64;
-
-    if(getContext().getTypeSizeInChars(Ty) > CharUnits::fromQuantity(Threshold))
-      return ABIArgInfo::getIndirect(CharUnits::fromQuantity(Align), true,
-                                     getContext().getTypeAlign(Ty) / 8 > Align);
-
     // If we have reached here, aggregates are passed directly by coercing to
     // another structure type. Padding is inserted if the offset of the
     // aggregate is unaligned.