Introducing the LLVM IR language syntax

Observe the LLVM IR assembly file, sum.ll:

target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.7.0"

define i32 @sum(i32 %a, i32 %b) #0 {
entry:
  %a.addr = alloca i32, align 4
  %b.addr = alloca i32, align 4
  store i32 %a, i32* %a.addr, align 4
  store i32 %b, i32* %b.addr, align 4
  %0 = load i32* %a.addr, align 4
  %1 = load i32* %b.addr, align 4
  %add = add nsw i32 %0, %1
  ret i32 %add
}

attributes #0 = { nounwind ssp uwtable ... }

The contents of an entire LLVM file, either assembly or bitcode, are said to define an LLVM module. The module is the LLVM IR top-level data structure. Each module contains a sequence of functions, which contains a sequence of basic blocks that contain a sequence of instructions. The module also contains peripheral entities to support this model...