UM-32

This is a C++ implementation of the UM-32 "Universal Machine". You can find the specification, various VM images, and more information about the contest which originally spawned this horror at boundvariable.org.

I wrote this because a friend did a Rust implementation.

Options

When compiling, the following options may be set:

COW_VECTOR=1

Use copy-on-write vectors for the arrays. This adds a performance penalty to array reads and writes; but, it make load program much faster in most cases. This is slightly worse for the midmark and sandmark benchmarks, but the uml language doesn't currently use self-modifying code, so it makes loading arrays (calling functions and branches) much faster.

TRACE_OP_CODES=<path/to/trace

Write each opcode executed to a binary file defined by the option. This is used to build the prediction options.

Performance

$ make bench
g++ (GCC) 8.2.1 20181127
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
Address sizes:       39 bits physical, 48 bits virtual
CPU(s):              4
On-line CPU(s) list: 0-3
Thread(s) per core:  2
Core(s) per socket:  2
Socket(s):           1
NUMA node(s):        1
Vendor ID:           GenuineIntel
CPU family:          6
Model:               78
Model name:          Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz
Stepping:            3
CPU MHz:             3204.468
CPU max MHz:         3400.0000
CPU min MHz:         400.0000
BogoMIPS:            5618.00
Virtualization:      VT-x
L1d cache:           32K
L1i cache:           32K
L2 cache:            256K
L3 cache:            4096K
NUMA node0 CPU(s):   0-3
Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb invpcid_single pti tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: 400 MHz - 3.40 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 3.40 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 3.20 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

./um samples/midmark.um
 == UM beginning stress test / benchmark.. ==
4.   12345678.09abcdef
3.   6d58165c.2948d58d
2.   0f63b9ed.1d9c4076
1.   8dba0fc0.64af8685
0.   583e02ae.490775c0
Benchmark complete.

real 0m0.225s
user 0m0.221s
sys  0m0.003s

./um samples/sandmark.umz
trying to Allocate array of size 0..
trying to Abandon size 0 allocation..
trying to Allocate size 11..
trying Array Index on allocated array..
trying Amendment of allocated array..
checking Amendment of allocated array..
trying Alloc(a,a) and amending it..
comparing multiple allocations..
pointer arithmetic..
check old allocation..
simple tests ok!
about to load program from some allocated array..
success.
verifying that the array and its copy are the same...
success.
testing aliasing..
success.
free after loadprog..
success.
loadprog ok.
 == SANDmark 19106 beginning stress test / benchmark.. ==
100. 12345678.09abcdef
99.  6d58165c.2948d58d
98.  0f63b9ed.1d9c4076

    ...

3.   7c7394b2.476c1ee5
2.   f3a52453.19cc755d
1.   2c80b43d.5646302f
0.   a8d1619e.5540e6cf
SANDmark complete.

real 0m16.275s
user 0m16.234s
sys  0m0.006s

UML - The Universal Machine Language

What good is a VM without the ability to compile programs for it? The compiler directory includes a WIP compiler for a simple imperative programming language that compiles to the UM-32 machine.

The language supports two data types:

1. uint: A scalar platter.
2. array: A fixed-length array of platters. The layout is: [length, ix_0, ix_1, ..., ix_n]. String and array are synonyms.

The syntax borrows heavily from Python, for example, a hello world program may look like:

def _inner_print(cs: array, n: uint) -> void:
    if n:
        # there are characters left to print
        ix: uint = um.len(cs) - n
        um.putchar(cs[ix])

        # recurse
        _inner_print(cs, n - 1)
    else:
        # no more characters, print the trailing newline
        um.putchar(10)


def print(cs: array) -> void:
    _inner_print(cs, um.len(cs))


def main() -> void:
    print("hello world")

um.putchar is a built-in function which writes a single character to the terminal. um.len is a built-in function which returns the length of an array.

See compiler/README.rst for implementation details.