[mlir] silence unused-function warnings in table-generated code

[ftynse]

Use cross-platform macros

[jpienaar]

OOC is this something that could be handled consistently from the generated code side?

[mehdi_amini]

This is a bit ugly, if what Jacques mentions could be implemented it'd be better, in the meantime this is likely fine to get rid of the warning. Can you add a one line doc in both places explaining why this is there?

mlir/lib/Target/LLVMIR/Dialect/LLVMIR/LLVMToLLVMIRTranslation.cpp

 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/MatrixBuilder.h"
 #include "llvm/IR/Operator.h"
 
 using namespace mlir;
 using namespace mlir::LLVM;
 using mlir::LLVM::detail::getLLVMConstant;
 
+// The include below has a static function unused in this translation unit,
+// declare it as such to silence a warning.
+static LLVM_ATTRIBUTE_UNUSED ::llvm::GlobalValue::LinkageTypes
+convertLinkageToLLVM(::mlir::LLVM::Linkage value);
+
 #include "mlir/Dialect/LLVMIR/LLVMConversionEnumsToLLVM.inc"
 
 /// Convert MLIR integer comparison predicate to LLVM IR comparison predicate.
 static llvm::CmpInst::Predicate getLLVMCmpPredicate(ICmpPredicate p) {
   switch (p) {
   case LLVM::ICmpPredicate::eq:
     return llvm::CmpInst::Predicate::ICMP_EQ;
   case LLVM::ICmpPredicate::ne:

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

 #include "llvm/IR/Verifier.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 
 using namespace mlir;
 using namespace mlir::LLVM;
 using namespace mlir::LLVM::detail;
 
+// The include below has a static function unused in this translation unit,
+// declare it as such to silence a warning.
+static LLVM_ATTRIBUTE_UNUSED ::llvm::InlineAsm::AsmDialect
+convertAsmDialectToLLVM(::mlir::LLVM::AsmDialect value);
+
 #include "mlir/Dialect/LLVMIR/LLVMConversionEnumsToLLVM.inc"
 
 /// Builds a constant of a sequential LLVM type `type`, potentially containing
 /// other sequential types recursively, from the individual constant values
 /// provided in `constants`. `shape` contains the number of elements in nested
 /// sequential types. Reports errors at `loc` and returns nullptr on error.
 static llvm::Constant *
 buildSequentialConstant(ArrayRef<llvm::Constant *> &constants,