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ruby--ruby/tool/ruby_vm/views/_comptime_insn_stack_increase.erb
Alan Wu 89e7997622 Combine call info and cache to speed up method invocation
To perform a regular method call, the VM needs two structs,
`rb_call_info` and `rb_call_cache`. At the moment, we allocate these two
structures in separate buffers. In the worst case, the CPU needs to read
4 cache lines to complete a method call. Putting the two structures
together reduces the maximum number of cache line reads to 2.

Combining the structures also saves 8 bytes per call site as the current
layout uses separate two pointers for the call info and the call cache.
This saves about 2 MiB on Discourse.

This change improves the Optcarrot benchmark at least 3%. For more
details, see attached bugs.ruby-lang.org ticket.

Complications:
 - A new instruction attribute `comptime_sp_inc` is introduced to
 calculate SP increase at compile time without using call caches. At
 compile time, a `TS_CALLDATA` operand points to a call info struct, but
 at runtime, the same operand points to a call data struct. Instruction
 that explicitly define `sp_inc` also need to define `comptime_sp_inc`.
 - MJIT code for copying call cache becomes slightly more complicated.
 - This changes the bytecode format, which might break existing tools.

[Misc #16258]
2019-10-24 18:03:42 +09:00

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Text

%# -*- C -*-
%# Copyright (c) 2017 Urabe, Shyouhei. All rights reserved.
%#
%# This file is a part of the programming language Ruby. Permission is hereby
%# granted, to either redistribute and/or modify this file, provided that the
%# conditions mentioned in the file COPYING are met. Consult the file for
%# details.
%#
PUREFUNC(MAYBE_UNUSED(static int comptime_insn_stack_increase(int depth, int insn, const VALUE *opes)));
PUREFUNC(static rb_snum_t comptime_insn_stack_increase_dispatch(enum ruby_vminsn_type insn, const VALUE *opes));
rb_snum_t
comptime_insn_stack_increase_dispatch(enum ruby_vminsn_type insn, const VALUE *opes)
{
static const signed char t[] = {
% RubyVM::Instructions.each_slice 8 do |a|
<%= a.map { |i|
if i.has_attribute?('sp_inc')
'-127'
else
sprintf("%4d", i.rets.size - i.pops.size)
end
}.join(', ') -%>,
% end
};
signed char c = t[insn];
ASSERT_VM_INSTRUCTION_SIZE(t);
if (c != -127) {
return c;
}
else switch(insn) {
default:
UNREACHABLE;
% RubyVM::Instructions.each do |i|
% next unless i.has_attribute?('sp_inc')
% attr_function =
% if i.has_attribute?('comptime_sp_inc')
% "attr_comptime_sp_inc_#{i.name}"
% else
% "attr_sp_inc_#{i.name}"
% end
case <%= i.bin %>:
return <%= attr_function %>(<%=
i.opes.map.with_index do |v, j|
if v[:type] == 'CALL_DATA' && i.has_attribute?('comptime_sp_inc')
v = v.dup
v[:type] = 'CALL_INFO'
end
i.cast_from_VALUE v, "opes[#{j}]"
end.join(", ")
%>);
% end
}
}
int
comptime_insn_stack_increase(int depth, int insn, const VALUE *opes)
{
enum ruby_vminsn_type itype = (enum ruby_vminsn_type)insn;
return depth + (int)comptime_insn_stack_increase_dispatch(itype, opes);
}