我想加深我对 scala 编译阶段的了解。我知道某些事情必须在编译器中发生，但并不真正知道它们发生的顺序以及顺序应该如何影响我的编程。
我是否正确地说以下内容是编译器功能的完整列表？
- 解析程序
- 检查类型
- 做擦除
- 隐式转换
- 生成的字节码
- 优化
如果是这样，它执行这些阶段的顺序是什么？这个顺序如何影响程序员，尤其是类型级程序员？
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4309 次
4 回答
51
您可以使用 来查看阶段、它们的顺序和解释scalac -Xshow-phases。
在 2.11 中，用于-Xshow-phases -Ydebug显示启用和禁用阶段。
以下是 2.10.0 的情况：
» scalac -Xshow-phases
phase name id description
---------- -- -----------
parser 1 parse source into ASTs, perform simple desugaring
namer 2 resolve names, attach symbols to named trees
packageobjects 3 load package objects
typer 4 the meat and potatoes: type the trees
patmat 5 translate match expressions
superaccessors 6 add super accessors in traits and nested classes
extmethods 7 add extension methods for inline classes
pickler 8 serialize symbol tables
refchecks 9 reference/override checking, translate nested objects
selectiveanf 10
selectivecps 11
uncurry 12 uncurry, translate function values to anonymous classes
tailcalls 13 replace tail calls by jumps
specialize 14 @specialized-driven class and method specialization
explicitouter 15 this refs to outer pointers, translate patterns
erasure 16 erase types, add interfaces for traits
posterasure 17 clean up erased inline classes
lazyvals 18 allocate bitmaps, translate lazy vals into lazified defs
lambdalift 19 move nested functions to top level
constructors 20 move field definitions into constructors
flatten 21 eliminate inner classes
mixin 22 mixin composition
cleanup 23 platform-specific cleanups, generate reflective calls
icode 24 generate portable intermediate code
inliner 25 optimization: do inlining
inlineExceptionHandlers 26 optimization: inline exception handlers
closelim 27 optimization: eliminate uncalled closures
dce 28 optimization: eliminate dead code
jvm 29 generate JVM bytecode
terminal 30 The last phase in the compiler chain
于 2010-12-24T19:45:21.553 回答
10
你看过这里吗？该页面指向http://www.scala-lang.org/sites/default/files/sids/nielsen/Thu,%202009-05-28,%2008:13/compiler-phases-sid.pdf (PDF) ，它描述了 Scala 2.8 的编译器阶段。
于 2010-12-24T19:07:06.520 回答
2
除非您正在编写编译器插件，否则您真的不应该担心编译器阶段的顺序。即使对于类型级编程，您也应该关注语言语义。
例如，就擦除而言，了解静态与动态类型以及单独编译的模型很重要。同样，了解编译器应用隐式转换的条件也很重要。这些在编译周期中发生的地方只是一个实现细节。
于 2010-12-25T00:15:41.947 回答
2
Scala.js 0.6.23
phase name id description
---------- -- -----------
parser 1 parse source into ASTs, perform simple desugaring
jspretyper 2 capture pre-typer only tree info (for Scala.js)
namer 3 resolve names, attach symbols to named trees
packageobjects 4 load package objects
typer 5 the meat and potatoes: type the trees
jsinterop 6 prepare ASTs for JavaScript interop
patmat 7 translate match expressions
superaccessors 8 add super accessors in traits and nested classes
extmethods 9 add extension methods for inline classes
pickler 10 serialize symbol tables
xsbt-api 11
xsbt-dependency 12
refchecks 13 reference/override checking, translate nested objects
uncurry 14 uncurry, translate function values to anonymous classes
tailcalls 15 replace tail calls by jumps
specialize 16 @specialized-driven class and method specialization
explicitouter 17 this refs to outer pointers
erasure 18 erase types, add interfaces for traits
posterasure 19 clean up erased inline classes
lazyvals 20 allocate bitmaps, translate lazy vals into lazified defs
lambdalift 21 move nested functions to top level
constructors 22 move field definitions into constructors
flatten 23 eliminate inner classes
mixin 24 mixin composition
jscode 25 generate JavaScript code from ASTs
cleanup 26 platform-specific cleanups, generate reflective calls
delambdafy 27 remove lambdas
icode 28 generate portable intermediate code
inliner xx optimization: do inlining
inlinehandlers xx optimization: inline exception handlers
closelim xx optimization: eliminate uncalled closures
constopt xx optimization: optimize null and other constants
dce xx optimization: eliminate dead code
jvm 29 generate JVM bytecode
xsbt-analyzer 30
terminal 31 the last phase during a compilation run
Scala-Native 0.3.7
phase name id description
---------- -- -----------
parser 1 parse source into ASTs, perform simple desugaring
namer 2 resolve names, attach symbols to named trees
packageobjects 3 load package objects
typer 4 the meat and potatoes: type the trees
nativeinterop 5 prepare ASTs for Native interop
patmat 6 translate match expressions
superaccessors 7 add super accessors in traits and nested classes
extmethods 8 add extension methods for inline classes
pickler 9 serialize symbol tables
xsbt-api 10
xsbt-dependency 11
refchecks 12 reference/override checking, translate nested objects
uncurry 13 uncurry, translate function values to anonymous classes
tailcalls 14 replace tail calls by jumps
specialize 15 @specialized-driven class and method specialization
explicitouter 16 this refs to outer pointers
erasure 17 erase types, add interfaces for traits
posterasure 18 clean up erased inline classes
lazyvals 19 allocate bitmaps, translate lazy vals into lazified defs
lambdalift 20 move nested functions to top level
constructors 21 move field definitions into constructors
flatten 22 eliminate inner classes
mixin 23 mixin composition
nir 24
cleanup 25 platform-specific cleanups, generate reflective calls
delambdafy 26 remove lambdas
icode 27 generate portable intermediate code
inliner xx optimization: do inlining
inlinehandlers xx optimization: inline exception handlers
closelim xx optimization: eliminate uncalled closures
constopt xx optimization: optimize null and other constants
dce xx optimization: eliminate dead code
jvm 28 generate JVM bytecode
xsbt-analyzer 29
terminal 30 the last phase during a compilation run
于 2018-06-23T14:56:32.513 回答