[llvm] [SPIRV] Add support for the SPIR-V extension SPV_KHR_bfloat16 (PR #155645)

[Marcos Maronas via llvm-commits]

================
@@ -1222,6 +1222,12 @@ static void AddDotProductRequirements(const MachineInstr &MI,
   }
 }
 
+static bool isBFloat16Type(const SPIRVType *TypeDef) {
+  return TypeDef && TypeDef->getNumOperands() == 3 &&
+         TypeDef->getOpcode() == SPIRV::OpTypeFloat &&
+         TypeDef->getOperand(2).getImm() == SPIRV::FPEncoding::BFloat16KHR;
----------------
maarquitos14 wrote:

Should we also check the bitwidth? 

https://github.com/llvm/llvm-project/pull/155645