Pass actually pointer typed things to printf (#302)

Co-authored-by: Tim Besard <tim.besard@gmail.com>

Author: vchuravy

lib/intrinsics/src/printf.jl

@@ -38,18 +38,55 @@ end
         llvm_f, _ = create_function(T_int32, param_types)
         mod = LLVM.parent(llvm_f)
 
-        # generate IR
         IRBuilder() do builder
             entry = BasicBlock(llvm_f, "entry")
             position!(builder, entry)
 
+            # `printf` needs to be invoked very specifically, e.g., the format string needs
+            # to be a pointer to a string, and arguments need to match exactly what is
+            # expected by the format string, so we cannot rely on how the arguments to this
+            # function have been passed in (by `llvmcall`).
+            T_actual_args = LLVMType[]
+            actual_args = LLVM.Value[]
+            for (_, (arg, argtyp)) in enumerate(zip(parameters(llvm_f), arg_types))
+                if argtyp <: LLVMPtr
+                    # passed as i8*
+                    T,AS = argtyp.parameters
+                    actual_typ = LLVM.PointerType(convert(LLVMType, T), AS)
+                    actual_arg = bitcast!(builder, arg, actual_typ)
+                elseif argtyp <: Ptr
+                    T = eltype(argtyp)
+                    if T === Nothing
+                        T = Int8
+                    end
+                    actual_typ = LLVM.PointerType(convert(LLVMType, T))
+                    actual_arg = if value_type(arg) isa LLVM.PointerType
+                        # passed as i8* or ptr
+                        bitcast!(builder, arg, actual_typ)
+                    else
+                        # passed as i64
+                        inttoptr!(builder, arg, actual_typ)
+                    end
+                elseif argtyp <: Bool
+                    # passed as i8
+                    T = eltype(argtyp)
+                    actual_typ = LLVM.Int1Type()
+                    actual_arg = trunc!(builder, arg, actual_typ)
+                else
+                    actual_typ = convert(LLVMType, argtyp)
+                    actual_arg = arg
+                end
+                push!(T_actual_args, actual_typ)
+                push!(actual_args, actual_arg)
+            end
+
             str = globalstring_ptr!(builder, String(fmt); addrspace=AS.Constant)
 
             # invoke printf and return
             printf_typ = LLVM.FunctionType(T_int32, [T_pint8]; vararg=true)
             printf = LLVM.Function(mod, "printf", printf_typ)
             push!(function_attributes(printf), EnumAttribute("nobuiltin"))
-            chars = call!(builder, printf_typ, printf, [str, parameters(llvm_f)...])
+            chars = call!(builder, printf_typ, printf, [str, actual_args...])
 
             ret!(builder, chars)
         end