[C API] Add LLVMConstBinOp function.

[mjacob]

Summary

This is analog to the existing LLVMBuildBinOp function.

[mehdi_amini]

Test?
(Same for the previous patch from today)

[deadalnix]

Wouldn't LLVMBuildBinOp build a constant if both operand are constant and the operation allows for it? I have not double checked, but I think it does. Considering this, I'm not really sure what this brings to the table.

include/llvm-c/Core.h

 LLVMValueRef LLVMConstExactSDiv(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstFDiv(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstURem(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstSRem(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstFRem(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstAnd(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstOr(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstXor(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
+LLVMValueRef LLVMConstBinOp(LLVMOpcode Op, LLVMValueRef LHSConstant,
+                            LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstICmp(LLVMIntPredicate Predicate,
                            LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstFCmp(LLVMRealPredicate Predicate,
                            LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstShl(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstLShr(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstAShr(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant);
 LLVMValueRef LLVMConstGEP(LLVMValueRef ConstantVal,

lib/IR/Core.cpp

return wrap(ConstantExpr::getOr(unwrap<Constant>(LHSConstant),
                                   unwrap<Constant>(RHSConstant)));
 }
 
 LLVMValueRef LLVMConstXor(LLVMValueRef LHSConstant, LLVMValueRef RHSConstant) {
   return wrap(ConstantExpr::getXor(unwrap<Constant>(LHSConstant),
                                    unwrap<Constant>(RHSConstant)));
 }
 
+LLVMValueRef LLVMConstBinOp(LLVMOpcode Op, LLVMValueRef LHSConstant,
+                            LLVMValueRef RHSConstant) {
+  return wrap(ConstantExpr::get(map_from_llvmopcode(Op),
+                                unwrap<Constant>(LHSConstant),
+                                unwrap<Constant>(RHSConstant)));
+}
+
 LLVMValueRef LLVMConstICmp(LLVMIntPredicate Predicate,
                            LLVMValueRef LHSConstant, LLVMValueRef RHSConstant) {
   return wrap(ConstantExpr::getICmp(Predicate,
                                     unwrap<Constant>(LHSConstant),
                                     unwrap<Constant>(RHSConstant)));
 }
 
 LLVMValueRef LLVMConstFCmp(LLVMRealPredicate Predicate,