WIP: generate sysimg.so

[ihnorton]

DO NOT MERGE

This is an attempt to save and reload the startup image as a shared library, for #260. It gets to repl.c and calls several functions deep into sysimg.so, but segfaults at the first literal pointer (as predicted by Jeff).

• save bitcode
• compile to shared library linked against libjulia
• reload shared library at startup and set pointers
• replace all uses of literal_pointer_val with... (globals?)
• make deleteBody optional
• ???

[ihnorton]

Current backtrace, the segfault is at the literal_pointer_val emitted for a uv handle in julia_init_stdio.

#0  0x00007ffff4d0fff1 in julia_init_stdio () from /cmn/git/julia/usr/bin/../lib/sysimg.so
#1  0x00007ffff4e5ffc9 in julia_reinit_stdio () from /cmn/git/julia/usr/bin/../lib/sysimg.so
#2  0x00007ffff4e5f8cf in julia__start () from /cmn/git/julia/usr/bin/../lib/sysimg.so
#3  0x00007ffff4e5ff66 in julia__start1676 () from /cmn/git/julia/usr/bin/../lib/sysimg.so
#4  0x00007ffff6b8aae6 in jl_apply (f=0x1298f30, args=0x0, nargs=0) at julia.h:1023
#5  0x00007ffff6b8e483 in jl_trampoline (F=0x1298f30, args=0x0, nargs=0) at builtins.c:847
#6  0x00007ffff6b81df9 in jl_apply (f=0x1298f30, args=0x0, nargs=0) at julia.h:1023
#7  0x00007ffff6b865a1 in jl_apply_generic (F=0x1298eb0, args=0x0, nargs=0) at gf.c:1401
#8  0x0000000000403c46 in jl_apply (f=0x1298eb0, args=0x0, nargs=0) at /cmn/git/julia/src/julia.h:1020
#9  0x00000000004047c1 in true_main (argc=0, argv=0x7fffffffe1d0) at repl.c:263
#10 0x00007ffff6bee692 in julia_trampoline (argc=0, argv=0x7fffffffe1d0, pmain=0x4045f1 <true_main>) at init.c:646
#11 0x00000000004049b3 in main (argc=0, argv=0x7fffffffe1d0) at repl.c:303

[timholy]

Exciting stuff!

[StefanKarpinski]

!!!

[kmsquire]

You forgot one part...

• save bitcode
• compile to shared library linked against libjulia
• reload shared library at startup and set pointers
• replace all uses of literal_pointer_val with... (globals?)
• make deleteBody optional
• ???

• Profit!

;-)

[StefanKarpinski]

I also believe that stealing underpants is one of the steps.

[ViralBShah]

Awesome!

[ViralBShah]

Does this also make it possible to pre-compile packages?

[ihnorton]

No, there is a ways to go; literal_pointer_val is used all over codegen. I hope this infrastructure stuff is helpful, but it's only a start.