【发布时间】：2011-05-18 20:37:24
【问题描述】：
一段时间以来，我一直在尝试LLVM，仅仅是因为。然而，它确实比我想象的消耗了我更多的时间。
我曾涉足 C++ 绑定，但由于显而易见的原因，我多年前离开了 C++。我尝试了 OCaml 绑定，但我不喜欢 OCaml，主要是因为构建系统繁琐，还有其他问题。
所以我被LLVM module for Haskell 卡住了，它的类型非常安全，而且感觉非常Haskell。但是文档有些欠缺，因为唯一的例子是一些 Blog 中的例子。
简而言之，我已经开始为PL/0 做一个简单的编译器。经过两天的努力，我已经做到了这一点（解析器没问题，Parsec 是我的朋友）：
AST 模块
module AST where
data Statement
= Assign String Expression
| Call String
| Write String
| If Condition Statement
| While Condition Statement
| Begin [Statement]
deriving (Show, Eq)
data Condition
= Odd Expression
| Eq Expression Expression
| Ne Expression Expression
| Gt Expression Expression
| Lt Expression Expression
| Ge Expression Expression
| Le Expression Expression
deriving (Show, Eq)
data Expression
= Identifier String
| Number Integer
| Plus Expression Expression
| Minus Expression Expression
| Multiply Expression Expression
| Divide Expression Expression
deriving (Show, Eq)
data Block = Block {
blockConsts :: [(String, Integer)],
blockVars :: [String],
blockProcs :: [Procedure],
blockStatement :: Statement
}
deriving (Show, Eq)
data Procedure = Procedure String Block
deriving (Show, Eq)
代码生成模块：
module Codegen {-(writeModule)-} where
import LLVM.Core
import AST
import Data.Int (Int64)
import Data.Word (Word8, Word32)
codegenExpr :: [(String, Value (Ptr Int64))] -> Expression -> CodeGenFunction r (Value Int64)
codegenExpr ls (Identifier s) = case lookup s ls of
Nothing -> error $ "unknown identifier: " ++ s
(Just v) -> load v
codegenExpr _ (Number n) = return $ valueOf $ fromIntegral n
codegenExpr ls (Plus e1 e2) = arith ls e1 e2 iadd
codegenExpr ls (Minus e1 e2) = arith ls e1 e2 isub
codegenExpr ls (Multiply e1 e2) = arith ls e1 e2 imul
codegenExpr ls (Divide e1 e2) = arith ls e1 e2 idiv
arith ls e1 e2 f = do
lhs <- codegenExpr ls e1
rhs <- codegenExpr ls e2
f lhs rhs
codegenCond :: [(String, Value (Ptr Int64))] -> Condition -> CodeGenFunction r (Value Bool)
codegenCond ls (Eq e1 e2) = cnd ls e1 e2 CmpEQ
codegenCond ls (Ne e1 e2) = cnd ls e1 e2 CmpNE
codegenCond ls (Gt e1 e2) = cnd ls e1 e2 CmpGT
codegenCond ls (Lt e1 e2) = cnd ls e1 e2 CmpLT
codegenCond ls (Ge e1 e2) = cnd ls e1 e2 CmpGE
codegenCond ls (Le e1 e2) = cnd ls e1 e2 CmpLE
cnd ls e1 e2 f = do
lhs <- codegenExpr ls e1
rhs <- codegenExpr ls e2
cmp f lhs rhs
codegenStatement :: [(String, Value (Ptr Int64))] -> Statement -> CodeGenFunction () ()
codegenStatement ls (Assign id e) = case lookup id ls of
Nothing -> error $ "unknown identifier: " ++ id
(Just v) -> do
val <- codegenExpr ls e
store val v
codegenStatement ls (Begin stmts) = mapM_ (codegenStatement ls) stmts
codegenStatement ls (If cond s1) = do
ifbl <- newBasicBlock
thenbl <- newBasicBlock
cnd <- codegenCond ls cond
condBr cnd ifbl thenbl
defineBasicBlock ifbl
codegenStatement ls s1
ret ()
defineBasicBlock thenbl
ret ()
codegenStatement ls (While cond s) = do
exit <- newBasicBlock
while <- newBasicBlock
defineBasicBlock while
cnd <- codegenCond ls cond
codegenStatement ls s
condBr cnd while exit
defineBasicBlock exit
ret ()
codegenBlock :: [(String, Value (Ptr Int64))] -> Block -> CodeGenModule (Function ())
codegenBlock vls (Block _ vars _ stmt) = do
-- And here is the type error
func <- createFunction ExternalLinkage $ do
ls <- mapM named vars
codegenStatement (vls ++ ls) stmt
mapM_ (free . snd) ls
return func
where
named n = do
v <- alloca
return (n, v)
writeModule bl file = do
m <- newModule
defineModule m $ codegenBlock [] bl
writeBitcodeToFile file m
是的，有很多代码，但很完整。我得到的类型错误是这样的：
GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
[1 of 2] Compiling AST ( AST.hs, interpreted )
[2 of 2] Compiling Codegen ( Codegen.hs, interpreted )
Codegen.hs:71:13:
No instances for (IsFunction (),
FunctionArgs () (CodeGenFunction () ()) (CodeGenFunction r0 ()))
arising from a use of `createFunction'
Possible fix:
add instance declarations for
(IsFunction (),
FunctionArgs () (CodeGenFunction () ()) (CodeGenFunction r0 ()))
In the expression: createFunction ExternalLinkage
In a stmt of a 'do' expression:
func <- createFunction ExternalLinkage
$ do { ls <- mapM named vars;
codegenStatement (vls ++ ls) stmt;
mapM_ (free . snd) ls }
In the expression:
do { func <- createFunction ExternalLinkage
$ do { ls <- mapM named vars;
codegenStatement (vls ++ ls) stmt;
.... };
return func }
正如我所说，我已经从提到的 Block 中提取了大部分示例，并且它是这样写的。我不知道如何解决这个问题。
和往常一样，我花更多的时间来满足类型检查器的要求，而不是编写新代码。
【问题讨论】：
-
什么是行，错误信息指向？
-
-
关于 LLVM 模块的几句话。出于某种原因，Haddock 遗漏了很多函数，因此您确实需要查看源代码以了解所有内容（例如向量）。此外，synthesizer-llvm 包 (haskell.org/haskellwiki/Synthesizer) 可能是 hackage 上可用的最大 LLVM 示例，因此您可能也想看看那里。
-
@Lohn L：感谢您的提示，我离开了源代码，但我错过了从模块中获取函数的函数。这是否意味着如果我想在 Haskell 中调用
Function值，我必须自己携带它们？