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ruby--ruby/yjit.rb
Alan Wu d0772632bf YJIT: Fail gracefully while OOM for new entry points
Previously, YJIT crashes with rb_bug() when asked to compile new methods
while out of executable memory.

To handle this situation gracefully, this change keeps track of all the
blocks compiled each invocation in case YJIT runs out of memory in the
middle of a compliation sequence. The list is used to free all blocks in
case compilation fails.

yjit_gen_block() is renamed to gen_single_block() to make it distinct from
gen_block_version(). Call to limit_block_version() and block_t
allocation is moved into the function to help tidy error checking in the
outer loop.

limit_block_version() now returns by value. I feel that an out parameter
with conditional mutation is unnecessarily hard to read in code that
does not need to go for last drop performance. There is a good chance
that the optimizer is able to output identical code anyways.
2021-12-01 12:25:28 -05:00

276 lines
9.8 KiB
Ruby

# This module allows for introspection on YJIT, CRuby's experimental in-process
# just-in-time compiler. This module is for development purposes only;
# everything in this module is highly implementation specific and comes with no
# API stability guarantee whatsoever.
#
# This module is only defined when YJIT has support for the particular platform
# on which CRuby is built.
module RubyVM::YJIT
if defined?(Disasm)
def self.disasm(iseq, tty: $stdout && $stdout.tty?)
iseq = RubyVM::InstructionSequence.of(iseq)
blocks = blocks_for(iseq)
return if blocks.empty?
str = String.new
str << iseq.disasm
str << "\n"
# Sort the blocks by increasing addresses
sorted_blocks = blocks.sort_by(&:address)
highlight = ->(str) {
if tty
"\x1b[1m#{str}\x1b[0m"
else
str
end
}
cs = Disasm.new
sorted_blocks.each_with_index do |block, i|
str << "== BLOCK #{i+1}/#{blocks.length}: #{block.code.length} BYTES, ISEQ RANGE [#{block.iseq_start_index},#{block.iseq_end_index}) ".ljust(80, "=")
str << "\n"
comments = comments_for(block.address, block.address + block.code.length)
comment_idx = 0
cs.disasm(block.code, block.address).each do |i|
while (comment = comments[comment_idx]) && comment.address <= i.address
str << " ; #{highlight.call(comment.comment)}\n"
comment_idx += 1
end
str << sprintf(
" %<address>08x: %<instruction>s\t%<details>s\n",
address: i.address,
instruction: i.mnemonic,
details: i.op_str
)
end
end
block_sizes = blocks.map { |block| block.code.length }
total_bytes = block_sizes.sum
str << "\n"
str << "Total code size: #{total_bytes} bytes"
str << "\n"
str
end
def self.comments_for(start_address, end_address)
Primitive.comments_for(start_address, end_address)
end
def self.graphviz_for(iseq)
iseq = RubyVM::InstructionSequence.of(iseq)
cs = Disasm.new
highlight = ->(comment) { "<b>#{comment}</b>" }
linebreak = "<br align=\"left\"/>\n"
buff = +''
blocks = blocks_for(iseq).sort_by(&:id)
buff << "digraph g {\n"
# Write the iseq info as a legend
buff << " legend [shape=record fontsize=\"30\" fillcolor=\"lightgrey\" style=\"filled\"];\n"
buff << " legend [label=\"{ Instruction Disassembly For: | {#{iseq.base_label}@#{iseq.absolute_path}:#{iseq.first_lineno}}}\"];\n"
# Subgraph contains disassembly
buff << " subgraph disasm {\n"
buff << " node [shape=record fontname=\"courier\"];\n"
buff << " edge [fontname=\"courier\" penwidth=3];\n"
blocks.each do |block|
disasm = disasm_block(cs, block, highlight)
# convert newlines to breaks that graphviz understands
disasm.gsub!(/\n/, linebreak)
# strip leading whitespace
disasm.gsub!(/^\s+/, '')
buff << "b#{block.id} [label=<#{disasm}>];\n"
buff << block.outgoing_ids.map { |id|
next_block = blocks.bsearch { |nb| id <=> nb.id }
if next_block.address == (block.address + block.code.length)
"b#{block.id} -> b#{id}[label=\"Fall\"];"
else
"b#{block.id} -> b#{id}[label=\"Jump\" style=dashed];"
end
}.join("\n")
buff << "\n"
end
buff << " }"
buff << "}"
buff
end
def self.disasm_block(cs, block, highlight)
comments = comments_for(block.address, block.address + block.code.length)
comment_idx = 0
str = +''
cs.disasm(block.code, block.address).each do |i|
while (comment = comments[comment_idx]) && comment.address <= i.address
str << " ; #{highlight.call(comment.comment)}\n"
comment_idx += 1
end
str << sprintf(
" %<address>08x: %<instruction>s\t%<details>s\n",
address: i.address,
instruction: i.mnemonic,
details: i.op_str
)
end
str
end
end
# Return a hash for statistics generated for the --yjit-stats command line option.
# Return nil when option is not passed or unavailable.
def self.runtime_stats
# defined in yjit_iface.c
Primitive.get_yjit_stats
end
# Discard statistics collected for --yjit-stats.
def self.reset_stats!
# defined in yjit_iface.c
Primitive.reset_stats_bang
end
def self.stats_enabled?
Primitive.yjit_stats_enabled_p
end
def self.enabled?
Primitive.cexpr! 'rb_yjit_enabled_p() ? Qtrue : Qfalse'
end
def self.simulate_oom!
Primitive.simulate_oom_bang
end
# Avoid calling a method here to not interfere with compilation tests
if Primitive.yjit_stats_enabled_p
at_exit { _print_stats }
end
class << self
private
# Format and print out counters
def _print_stats
stats = runtime_stats
return unless stats
$stderr.puts("***YJIT: Printing YJIT statistics on exit***")
print_counters(stats, prefix: 'send_', prompt: 'method call exit reasons: ')
print_counters(stats, prefix: 'invokesuper_', prompt: 'invokesuper exit reasons: ')
print_counters(stats, prefix: 'leave_', prompt: 'leave exit reasons: ')
print_counters(stats, prefix: 'gbpp_', prompt: 'getblockparamproxy exit reasons: ')
print_counters(stats, prefix: 'getivar_', prompt: 'getinstancevariable exit reasons:')
print_counters(stats, prefix: 'setivar_', prompt: 'setinstancevariable exit reasons:')
print_counters(stats, prefix: 'oaref_', prompt: 'opt_aref exit reasons: ')
print_counters(stats, prefix: 'expandarray_', prompt: 'expandarray exit reasons: ')
print_counters(stats, prefix: 'opt_getinlinecache_', prompt: 'opt_getinlinecache exit reasons: ')
print_counters(stats, prefix: 'invalidate_', prompt: 'invalidation reasons: ')
side_exits = total_exit_count(stats)
total_exits = side_exits + stats[:leave_interp_return]
# Number of instructions that finish executing in YJIT.
# See :count-placement: about the subtraction.
retired_in_yjit = stats[:exec_instruction] - side_exits
# Average length of instruction sequences executed by YJIT
avg_len_in_yjit = retired_in_yjit.to_f / total_exits
# Proportion of instructions that retire in YJIT
total_insns_count = retired_in_yjit + stats[:vm_insns_count]
yjit_ratio_pct = 100.0 * retired_in_yjit.to_f / total_insns_count
# Number of failed compiler invocations
compilation_failure = stats[:compilation_failure]
$stderr.puts "bindings_allocations: " + ("%10d" % stats[:binding_allocations])
$stderr.puts "bindings_set: " + ("%10d" % stats[:binding_set])
$stderr.puts "compilation_failure: " + ("%10d" % compilation_failure) if compilation_failure != 0
$stderr.puts "compiled_iseq_count: " + ("%10d" % stats[:compiled_iseq_count])
$stderr.puts "compiled_block_count: " + ("%10d" % stats[:compiled_block_count])
$stderr.puts "invalidation_count: " + ("%10d" % stats[:invalidation_count])
$stderr.puts "constant_state_bumps: " + ("%10d" % stats[:constant_state_bumps])
$stderr.puts "inline_code_size: " + ("%10d" % stats[:inline_code_size])
$stderr.puts "outlined_code_size: " + ("%10d" % stats[:outlined_code_size])
$stderr.puts "total_exit_count: " + ("%10d" % total_exits)
$stderr.puts "total_insns_count: " + ("%10d" % total_insns_count)
$stderr.puts "vm_insns_count: " + ("%10d" % stats[:vm_insns_count])
$stderr.puts "yjit_insns_count: " + ("%10d" % stats[:exec_instruction])
$stderr.puts "ratio_in_yjit: " + ("%9.1f" % yjit_ratio_pct) + "%"
$stderr.puts "avg_len_in_yjit: " + ("%10.1f" % avg_len_in_yjit)
print_sorted_exit_counts(stats, prefix: "exit_")
end
def print_sorted_exit_counts(stats, prefix:, how_many: 20, left_pad: 4)
exits = []
stats.each do |k, v|
if k.start_with?(prefix)
exits.push [k.to_s.delete_prefix(prefix), v]
end
end
exits = exits.sort_by { |name, count| -count }[0...how_many]
total_exits = total_exit_count(stats)
top_n_total = exits.map { |name, count| count }.sum
top_n_exit_pct = 100.0 * top_n_total / total_exits
$stderr.puts "Top-#{how_many} most frequent exit ops (#{"%.1f" % top_n_exit_pct}% of exits):"
longest_insn_name_len = exits.map { |name, count| name.length }.max
exits.each do |name, count|
padding = longest_insn_name_len + left_pad
padded_name = "%#{padding}s" % name
padded_count = "%10d" % count
percent = 100.0 * count / total_exits
formatted_percent = "%.1f" % percent
$stderr.puts("#{padded_name}: #{padded_count} (#{formatted_percent}%)" )
end
end
def total_exit_count(stats, prefix: "exit_")
total = 0
stats.each do |k,v|
total += v if k.start_with?(prefix)
end
total
end
def print_counters(counters, prefix:, prompt:)
$stderr.puts(prompt)
counters = counters.filter { |key, _| key.start_with?(prefix) }
counters.filter! { |_, value| value != 0 }
counters.transform_keys! { |key| key.to_s.delete_prefix(prefix) }
if counters.empty?
$stderr.puts(" (all relevant counters are zero)")
return
end
counters = counters.to_a
counters.sort_by! { |(_, counter_value)| counter_value }
longest_name_length = counters.max_by { |(name, _)| name.length }.first.length
total = counters.sum { |(_, counter_value)| counter_value }
counters.reverse_each do |(name, value)|
percentage = value.fdiv(total) * 100
$stderr.printf(" %*s %10d (%4.1f%%)\n", longest_name_length, name, value, percentage);
end
end
end
end