[Clang][BFloat16] Upgrade __bf16 by supporting increment/decrement operations

[joshua-arch1]

Summary

Since __bf16 has been upgraded from a storage-only type to an arithmetic type in https://reviews.llvm.org/rGe62175736551abf40a3410bc246f58e650eb8158, it should support all the basic arithmetic operations like other float types, including increment and decrement.

[pengfei]

LGTM.

clang/lib/CodeGen/CGExprScalar.cpp

2766–2767

Update the comment here.

[zahiraam]

LGTM. After fixing the comment that @pengfei mentions.

clang/lib/CodeGen/CGExprScalar.cpp

// Floating point.
     }
 
     if (value->getType()->isFloatTy())
       amt = llvm::ConstantFP::get(VMContext,
                                   llvm::APFloat(static_cast<float>(amount)));
     else if (value->getType()->isDoubleTy())
       amt = llvm::ConstantFP::get(VMContext,
                                   llvm::APFloat(static_cast<double>(amount)));
     else {
-      // Remaining types are Half, LongDouble, __ibm128 or __float128. Convert
-      // from float.
+      // Remaining types are Half, Bfloat16, LongDouble, __ibm128 or __float128. 
+      // Convert from float.
       llvm::APFloat F(static_cast<float>(amount));
       bool ignored;
       const llvm::fltSemantics *FS;
       // Don't use getFloatTypeSemantics because Half isn't
       // necessarily represented using the "half" LLVM type.
       if (value->getType()->isFP128Ty())
         FS = &CGF.getTarget().getFloat128Format();
       else if (value->getType()->isHalfTy())
         FS = &CGF.getTarget().getHalfFormat();
+      else if (value->getType()->isBFloatTy())
+        FS = &CGF.getTarget().getBFloat16Format();
       else if (value->getType()->isPPC_FP128Ty())
         FS = &CGF.getTarget().getIbm128Format();
       else
         FS = &CGF.getTarget().getLongDoubleFormat();
       F.convert(*FS, llvm::APFloat::rmTowardZero, &ignored);
       amt = llvm::ConstantFP::get(VMContext, F);
     }
     value = Builder.CreateFAdd(value, amt, isInc ? "inc" : "dec");

clang/test/Sema/arm-bfloat.cpp

 
 void test(bool b) {
   __bf16 bf16;
 
   bf16 + bf16;
   bf16 - bf16;
   bf16 * bf16;
   bf16 / bf16;
+  ++bf16;
+  --bf16;
 
   __fp16 fp16;
 
   bf16 + fp16;
   fp16 + bf16;
   bf16 - fp16;
   fp16 - bf16;
   bf16 * fp16;
void test_vector(bfloat16x4_t a, bfloat16x4_t b, float16x4_t c) {
   a * c;
   a / c;
   c + b;
   c - b;
   c * b;
   c / b;
 }
 #endif
 No newline at end of file