llvm ir in graalvm: multi-level, polyglot debugging...

LLVM IR IN GRAALVM:MULTI-LEVEL, POLYGLOTDEBUGGING WITH SULONG

Jacob Kreindl

2019 European LLVM Developers’ Meeting, April 8-9, 2019

MOTIVATION

April 9, 2019 Jacob Kreindl, EuroLLVM’19 2

LLVM IR

Binary

MOTIVATION


LLVM IR

Binary

Debuggers for

Dynamic Languages

MOTIVATION


LLVM IR

Binary

Debuggers for

Dynamic Languages

Debuggers for

Native Code

GRAALVM


LLVM IR

GRAALVM


LLVM IR

Execute & Debug

GRAALVM


LLVM IR

Execute & Debug

Execute

GRAALVM


LLVM IR

Execute & Debug

Execute & Debug

Debug

GRAALVM FOR DYNAMIC LANGUAGES




Language

Front-End

Language

Front-End

Language

Front-End



Language

Front-End

Language

Front-End

Language

Front-EndLanguage-Agnostic

AST

op1

op2 if

elsethen

op3 op4

Source

Location



Debugger

Back-End

Chrome

Debugger

Netbeans

Debugger

Other

Front-Ends

Language

Front-End

Language

Front-End

Language

Front-EndLanguage-Agnostic

AST

op1

op2 if

elsethen

op3 op4

Source

Location

SULONG – THE LLI IN GRAALVM


LLVM-IR

LLVM Front-End

(Clang, Dragonegg, …)

Sulong

Language-Agnostic

AST (IR-Level)

block

phi %8 store

42getelementptr

%1 4

Debugger

Back-End

SOURCE-LEVEL DEBUGGING WITH SULONG


LLVM-IR Sulong

Language-Agnostic

AST (IR-Level)

+ Run-Time Debug Information

(Source-Level)

LLVM Front-End


Debugger

Back-Endwith Debug

Information+ DebugInfo

Parser

block

phi %8 store

42getelementptr

%1 4

Scope &

LocationValue Tracking

(@llvm.dbg.*) Abstraction to

Source-Level

DEBUGGING NATIVE EXTENSIONS OF DYNAMIC LANGUAGE PROGRAMS


Ruby Program

+ Native Extension



One AST

built from multiple language front-ends

LLVM

IR

Ruby Program

+ Native Extension



GraalVM

Debugger

Back-End

One AST

built from multiple language front-ends

LLVM

IR

Ruby Program

+ Native Extension

Debugging a C-Extension for a Ruby Program with Sulong/TruffleRuby

DEMO

IR-LEVEL DEBUGGING WITH SULONG


LLVM-IR Sulong

Language-Agnostic

Program Representation

+ Run-Time Debug Information

LLVM Front-End


Debugger

Back-End

+ .ll Parser

op1

op2 if

elsethen

op3 op4

Location

in ll-File

Abstraction to

IR-Level

.bc + .ll File

MEMORY ACCESS IN SULONG



Native Mode

All allocations on the native heap

Using java.lang.Unsafe

Accessing illegal memory leads to

Segfault


{ i32, i32 }* 0x00abcdef

42 84

may not be

allocated


Native Mode

All allocations on the native heap

Using java.lang.Unsafe

Accessing illegal memory leads to

Segfault

Sandboxed Mode

All allocations as Java objects

Only in GraalVM Enterprise Edition

Guaranteed memory safety


{ i32, i32 }* 0x00abcdef

42 84

{ i32, i32 }* <managed>

{ i32, i32 } <managed>

i32 42

i32 84

may not be

allocated

Always safe

to access

Debugging & Tracing a C-Program at IR-Level with Managed Sulong

DEMO

YOU CAN TRY IT YOURSELF

Download GraalVM at https://www.graalvm.org/

GraalVM Community Edition is Open Source: https://github.com/oracle/graal


https://www.graalvm.org/

https://github.com/oracle/graal

IN CONCLUSION


Execute & Debug

LLVM IR

IN CONCLUSION

Same Debugger Front-End

for all Languages


Execute & Debug

LLVM IR

IN CONCLUSION


for all Languages

Source-Level Stepping & Breakpoints


Execute & Debug

LLVM IR

IN CONCLUSION


for all Languages


Cross-Language Symbol Inspection


Execute & Debug

LLVM IR

IN CONCLUSION


for all Languages


Cross-Language Symbol Inspection

IR-Level Debugging


Execute & Debug

LLVM IR

SYSTEM OVERVIEW


Truffle

JVM + Graal

GraalVM

Interpreter for Dynamic Language(TruffleRuby, GraalPython,

Code in Dynamic Language(Ruby, Python,

Sulong

LLVM-IR+ Debug Information

Native Extension(C/C++, Fortran,

Truffle Debugger

Chrome Debugger

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