FunTAL: Reasonably Mixing a Functional Language with Assemblyeuisuny/talks/funtal.pdf · 2020-01-04 · TAL : Typed Assembly Language • Types at assembly level • Stack-based TAL

FunTAL: Reasonably Mixing a Functional

Language with Assembly

Daniel Patterson, Jamie Perconti, Christos Dimoulas, Amal Ahmed

Irene Yoon

Mixed Language Programs

High-level LanguageHigh-level Language

Low-level Language


High-level Language

Inline assembly


High-level Language

Inline assembly

+ hardware access

+ fine-tune performance


• no safety guarantees

• low-level code can

• alter control flow

• mutate inaccessible values

• introduce security vulnerabilities


High-level Language

Assembly

JITThis portion can be

compiled!


High-level Language

Assembly

JITThis portion can be

compiled!

Verification of correctness?


High-level Language

Assembly


=

Need to prove contextual equivalence

Goals

• Safely mix high-level and low-level code

• Prove contextual equivalence of mixed programs

FunTAL

• Multi-language

• Embeds assembly in typed functional language

• Embeds typed functional language in assembly

FunTAL Goals

• Appropriate granularity for comparison

• Keep low-level language low and high-level language high

• Mix high-level and low-level language

• Prove (contextual) equivalence

Fun + TAL

Fun : Functional Language

• Simply Typed Lambda Calculus

• (iso-) recursive types

Fun + Assembly

Assembly

Assembly

• Inherently non-compositional

Assembly


direct jump

Assembly


_______ _______ _______ _______ _______ _______

call stack

direct jump

Mixing Fun

direct jump

_______ _______ _______ _______ _______ _______

call stack

Fun

compositional

Mixing Fun

Fun

compositional

• Need to constrain non-compositional behavior

Fun + (compositional) TAL

TAL : Typed Assembly Language

• Types at assembly level

• Stack-based TAL = STAL

[Morrisett, Crary, Glew, Walker ’98]





HeapTyping





HeapTyping

Type Env





HeapTyping

Type EnvRegister File

Typing





HeapTyping


Typing

Stack Typing





HeapTyping


Typing

Stack Typing

instr; … ; jmp l

Fun + (compositional) TAL

type parameter register stack

typing preconditions







TAL in Fun

Fun

TAL

_________________ _________________

Granularity

_________________ _________________

assembly components

_________________ _________________

assembly components

_________________ _________________

instr. sequence

(basic block)

localheap

fragment

assembly components

TAL Components

• Represent one or more basic blocks

• Local heap fragment - locations to code blocks used in jumps

• Similar granularity to expressions in Fun

instr. sequence

localheap

fragment

Fun + (compositional, TAL component-based)

FunTAL Goals





_________________ _________________

_________________ _________________ Input Output



return addr l l

Return Marker

• return marker specifies register/stack position where return continuation is stored

Result Type

• Must provide components with return continuations

• Called f/ assembly jump: jump to next instr.

• Called f/ high level code: contain halt

End / Halt

Polymorphic return marker

Polymorphic return markerI know

the future!!!

Polymorphic return marker

caller instantiates where control flow should go next

FunTAL Goals





jmp

call

bz

Component Based Jumps

• intra-component jump jmp

• inter-component jump ret

• inter-component jump call

jmp (intra-component)

“current component will terminate by jumping to a same TAL component”

=> same return marker

jmp (intra-component)

“current component will terminate by jumping to a same TAL component”

=> same return marker

ret (intra-component)

“returning from a component(jumping back to different component)”

ret (intra-component)

“returning from a component (jumping back to different component)”

=> no restrictions on return marker

call (inter-component)

“current component will terminate by halting”


• STAL stack-tail polymorphism : “callee-saved” stack tail

“current component will terminate by halting”

“current component will terminate by jumping to another TAL component”


FunTAL Goals





def fn(x): _________________ _________________

def fn(x): _________________ _________________

need multi-language!

Multi-Language• Syntax of both languages combined

• Boundary terms added to mediate interactions

•

[Matthews-Findler `07]

Fun TAL (e) TAL Fun (e)



•





•


translation meta-functionreduce


Multi-Language FunTAL




Fun in TAL

def fn(x): _________________ _________________

Import (Fun in TAL)

FunTAL Goals






High-level Language

Assembly


=

Need to prove contextual equivalence

Logical Relation for Multi-Language

https://dbp.io/talks/2017/funtal-pldi.pdf

Equivalence in Fun

“related inputs result in related outputs”


Equivalence in TAL


Demo

• https://dbp.io/artifacts/funtal/

https://dbp.io/artifacts/funtal/

Future Work

• Verification of JIT transformations

• Compositional compiler correctness

• Return markers for slightly higher-level languages

Goals

• Safely mix high-level and low-level code

• Prove contextual equivalence of mixed programs

FunTAL: Reasonably Mixing a Functional Language with Assemblyeuisuny/talks/funtal.pdf · 2020-01-04 · TAL : Typed Assembly Language • Types at assembly level • Stack-based TAL

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