LLVM

• It provides tools for converting custom abstract syntax tree(AST) into intermediate representation(IR)
• codegen()

• It analyzes IR and optimize it.

• It convert IR into the machine code.

• i1 boolean, flag
• iN integer, uN unsigned integer. N can be any number between 1 and 2³² - 1.
• <ty>* pointer, ptr can be used to automatically infer the pointer type

Global variables and functions start with @. Local variables and unnamed variables start with %.

• <ty> *alloca <ty>
• define <ty> <fn>(<ty> <var>, ...) { ... } define function
• declare <ty> <fn>(<ty>, ...) external functions
• alloca <ty>[, <ty> <NumElements>][, align <alignment>]
• load <ty>, <ty*> <val> load from memory
• store <ty> <val>, <ty*> <ptr>
• add <wrap> <ty> <val1>, <val2>
  • sub mul …
• icmp <cmp>, <ty> <val1>, <val2>
• br i1 <cond>, label <val1>, label <val2>, br label <val>
• call <ty> <fn>(...)
• ret <ty> <val>
• getelementptr <ty>, <ty> *<ptr>, <ty> <pos>, <ty> <offset>

Error handling using libunwind

• resume <ty> <val>
• landingpad <ty> <val> [cleanup] [catch <ty> <val>] [filter <ty> <val>]

• If the name is a number they must be in order starting from 0 which representing the entry point.
• @var global collapsed:: true
  • Function name must start with @?
• %var local variable
• label: label
• #attr attribute of a function
  • The attributes are specified at the end of the .ll file, and it is assigned to a function by adding it at the end of the function declaration: define <ty> <fn>(...) #attr { ... }
• !flag flag