Sample POSIX "Hello World" Application (ruby-llvm)

llvm_puts.rb

require 'llvm/core'
require 'llvm/analysis'
require 'llvm/execution_engine'

mod = LLVM::Module.new("test")

str = "Hello, World!"

STRING = mod.globals.add(LLVM::Array(LLVM::Int8, str.size + 1), "str") do |value|
           value.linkage         = :internal
           value.unnamed_addr    = true
           value.global_constant = 1
           value.initializer     = LLVM::ConstantArray.string(str)
         end

fn_puts = mod.functions.add("puts", [LLVM::Pointer(LLVM::Int8)], LLVM::Int) do |fn|
            fn.add_attribute(:no_unwind_attribute)
          end

mod.functions.add("main", [], LLVM::Int) do |fn|
  fn.basic_blocks.append.build do |builder|
    ptr = builder.gep(STRING, [LLVM::Int(0), LLVM::Int(0)])
    builder.call(fn_puts, ptr)
    builder.ret LLVM::Int(0)
  end
end

mod.verify!
mod.dump

# ; ModuleID = 'test'
# 
# @str = internal unnamed_addr constant [14 x i8] c"Hello, World!\00"
# 
# ; Function Attrs: nounwind
# declare i32 @puts(i8*) #0
# 
# define i32 @main() {
#   %1 = call i32 @puts(i8* getelementptr inbounds ([14 x i8]* @str, i32 0, i32 0))
#   ret i32 0
# }

# ---- JIT
LLVM.init_jit

engine = LLVM::JITCompiler.new(mod)
engine.run_function(mod.functions["main"])