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ruby--ruby/tool/ruby_vm/views/_mjit_compile_insn.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

87 lines
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% # -*- C -*-
% # Copyright (c) 2018 Takashi Kokubun. 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.
fprintf(f, "{\n");
{
MAYBE_UNUSED(int pc_moved_p) = FALSE;
% # compiler: Prepare operands which may be used by `insn.call_attribute`
% insn.opes.each_with_index do |ope, i|
MAYBE_UNUSED(<%= ope.fetch(:decl) %>) = (<%= ope.fetch(:type) %>)operands[<%= i %>];
% end
%
% # JIT: Declare stack_size to be used in some macro of _mjit_compile_insn_body.erb
if (status->local_stack_p) {
fprintf(f, " MAYBE_UNUSED(unsigned int) stack_size = %u;\n", b->stack_size);
}
%
% # JIT: Declare variables for operands, popped values and return values
% insn.declarations.each do |decl|
fprintf(f, " <%= decl %>;\n");
% end
% # JIT: Set const expressions for `RubyVM::OperandsUnifications` insn
% insn.preamble.each do |amble|
fprintf(f, "<%= amble.expr.sub(/const \S+\s+/, '') %>\n");
% end
%
% # JIT: Initialize operands
% insn.opes.each_with_index do |ope, i|
fprintf(f, " <%= ope.fetch(:name) %> = (<%= ope.fetch(:type) %>)0x%"PRIxVALUE";", operands[<%= i %>]);
% case ope.fetch(:type)
% when 'ID'
comment_id(f, (ID)operands[<%= i %>]);
% when 'CALL_DATA'
comment_id(f, ((CALL_DATA)operands[<%= i %>])->ci.mid);
% when 'VALUE'
if (SYMBOL_P((VALUE)operands[<%= i %>])) comment_id(f, SYM2ID((VALUE)operands[<%= i %>]));
% end
fprintf(f, "\n");
% end
%
% # JIT: Initialize popped values
% insn.pops.reverse_each.with_index.reverse_each do |pop, i|
fprintf(f, " <%= pop.fetch(:name) %> = stack[%d];\n", b->stack_size - <%= i + 1 %>);
% end
%
% # JIT: move sp and pc if necessary
<%= render 'mjit_compile_pc_and_sp', locals: { insn: insn } -%>
%
% # JIT: Print insn body in insns.def
<%= render 'mjit_compile_insn_body', locals: { insn: insn } -%>
%
% # JIT: Set return values
% insn.rets.reverse_each.with_index do |ret, i|
% # TOPN(n) = ...
fprintf(f, " stack[%d] = <%= ret.fetch(:name) %>;\n", b->stack_size + (int)<%= insn.call_attribute('sp_inc') %> - <%= i + 1 %>);
% end
%
% # JIT: We should evaluate ISeq modified for TracePoint if it's enabled. Note: This is slow.
% unless insn.always_leaf?
fprintf(f, " if (UNLIKELY(!mjit_call_p)) {\n");
fprintf(f, " reg_cfp->sp = vm_base_ptr(reg_cfp) + %d;\n", b->stack_size + (int)<%= insn.call_attribute('sp_inc') %>);
if (!pc_moved_p) {
fprintf(f, " reg_cfp->pc = original_body_iseq + %d;\n", next_pos);
}
fprintf(f, " RB_DEBUG_COUNTER_INC(mjit_cancel_invalidate_all);\n");
fprintf(f, " goto cancel;\n");
fprintf(f, " }\n");
% end
%
% # compiler: Move JIT compiler's internal stack pointer
b->stack_size += <%= insn.call_attribute('sp_inc') %>;
}
fprintf(f, "}\n");
%
% # compiler: If insn has conditional JUMP, the branch which is not targeted by JUMP should be compiled too.
% if insn.expr.expr =~ /if\s+\([^{}]+\)\s+\{[^{}]+JUMP\([^)]+\);[^{}]+\}/
compile_insns(f, body, b->stack_size, pos + insn_len(insn), status);
% end
%
% # compiler: If insn returns (leave) or does longjmp (throw), the branch should no longer be compiled. TODO: create attr for it?
% if insn.expr.expr =~ /\sTHROW_EXCEPTION\([^)]+\);/ || insn.expr.expr =~ /\bvm_pop_frame\(/
b->finish_p = TRUE;
% end