A pretty printer for llvm-hs-pure. Goal is to be able to pretty print a sufficiently large subset of the LLVM AST from pure Haskell without having to go through the C++ API.

Note: It is possible to construct llvm-hs-pure ASTs that are invalid ASTs and as such there is no meaningful way to print them. Always run the LLVM verifier on your AST to test it is sound. If you encounter incomplete pattern matches using this library you likely have constructed invalid IR.

There is a single function ppllvm that maps a LLVM.AST.Module to a Text.

import LLVM.AST import LLVM.Pretty (ppllvm) ppllvm :: Module -> Text

Individual LLVM elements (constants, instructions) can be printed using the the polymorphic ppll function for any LLVM structure that implements the PP typeclass.

# This is only necessary for running the test suite sudo apt-get install llvm-9-dev

The test suite currently consists of round tripping a LLVM IR from correct IR outputted by the llc toolchain, parsing into llvm-hs AST and then printing it back out and comparing it with the original textual form to see if the pretty printer faithfully preserves the structure. The sample modules are in tests/.

Using stack:

$ stack build $ stack test

Using cabal:

$ cabal run $ cabal run -- tests/simple.ll

If you're using Nix then:

$ nix-shell $ cabal run

To try out the standalone example run:

$ stack repl $ :load Example.hs main

Consider the basic example LLVM module.

; ModuleID = 'example-llvm-module' define i8 @f(i8 %x){ entry: ret i8 %x }

Using the LLVM.AST we construct the type and feed it to the pretty printer.

module Standalone where -- Pretty Printer import LLVM.Pretty (ppllvm) -- AST import qualified LLVM.AST as AST import qualified LLVM.AST.Linkage as Linkage import qualified LLVM.AST.Visibility as Visibility import qualified LLVM.AST.CallingConvention as Convention import Data.Text.Lazy.IO as TIO astModule :: AST.Module astModule = AST.Module { AST.moduleName = "example-llvm-module" , AST.moduleDataLayout = Nothing , AST.moduleTargetTriple = Nothing , AST.moduleDefinitions = [ AST.GlobalDefinition (AST.Function Linkage.External Visibility.Default Nothing Convention.C [] (AST.IntegerType 8) (AST.Name "f") ([AST.Parameter (AST.IntegerType 8) (AST.Name "x") []], False) [] Nothing Nothing 0 Nothing Nothing [ AST.BasicBlock (AST.Name "entry") [] (AST.Do (AST.Ret (Just (AST.LocalReference (AST.IntegerType 8) (AST.Name "x") ) ) [] ) ) ] ) ] } main :: IO () main = TIO.putStrLn (ppllvm astModule)

Released under the MIT License.

Copyright (c) 2014-2020, Stephen Diehl Copyright (c) 2015 Cedric Shock