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require 'ruby_vm/mjit/assembler'
require 'ruby_vm/mjit/block'
require 'ruby_vm/mjit/block_stub'
require 'ruby_vm/mjit/branch_stub'
require 'ruby_vm/mjit/code_block'
require 'ruby_vm/mjit/context'
require 'ruby_vm/mjit/exit_compiler'
require 'ruby_vm/mjit/insn_compiler'
require 'ruby_vm/mjit/instruction'
require 'ruby_vm/mjit/invariants'
require 'ruby_vm/mjit/jit_state'
module RubyVM::MJIT
# Compilation status
KeepCompiling = :KeepCompiling
CantCompile = :CantCompile
EndBlock = :EndBlock
# Ruby constants
Qtrue = Fiddle::Qtrue
Qfalse = Fiddle::Qfalse
Qnil = Fiddle::Qnil
Qundef = Fiddle::Qundef
# Callee-saved registers
# TODO: support using r12/r13 here
EC = :r14
CFP = :r15
SP = :rbx
# Scratch registers: rax, rcx
class Compiler
attr_accessor :write_pos
def self.decode_insn(encoded)
INSNS.fetch(C.rb_vm_insn_decode(encoded))
end
# @param mem_block [Integer] JIT buffer address
# @param mem_size [Integer] JIT buffer size
def initialize(mem_block, mem_size)
@cb = CodeBlock.new(mem_block: mem_block, mem_size: mem_size / 2)
@ocb = CodeBlock.new(mem_block: mem_block + mem_size / 2, mem_size: mem_size / 2, outlined: true)
@exit_compiler = ExitCompiler.new
@insn_compiler = InsnCompiler.new(@ocb, @exit_compiler)
@leave_exit = Assembler.new.then do |asm|
@exit_compiler.compile_leave_exit(asm)
@ocb.write(asm)
end
end
# Compile an ISEQ from its entry point.
# @param iseq `RubyVM::MJIT::CPointer::Struct_rb_iseq_t`
# @param cfp `RubyVM::MJIT::CPointer::Struct_rb_control_frame_t`
def compile(iseq, cfp)
# TODO: Support has_opt
return if iseq.body.param.flags.has_opt
asm = Assembler.new
asm.comment("Block: #{iseq.body.location.label}@#{C.rb_iseq_path(iseq)}:#{iseq.body.location.first_lineno}")
compile_prologue(asm)
compile_block(asm, jit: JITState.new(iseq:, cfp:))
iseq.body.jit_func = @cb.write(asm)
rescue Exception => e
$stderr.puts e.full_message # TODO: check verbose
end
# Continue compilation from a block stub.
# @param block_stub [RubyVM::MJIT::BlockStub]
# @param cfp `RubyVM::MJIT::CPointer::Struct_rb_control_frame_t`
# @return [Integer] The starting address of the compiled block stub
def block_stub_hit(block_stub, cfp)
# Update cfp->pc for `jit.at_current_insn?`
cfp.pc = block_stub.pc
# Prepare the jump target
new_asm = Assembler.new.tap do |asm|
jit = JITState.new(iseq: block_stub.iseq, cfp:)
compile_block(asm, jit:, pc: block_stub.pc, ctx: block_stub.ctx)
end
# Rewrite the block stub
if @cb.write_addr == block_stub.end_addr
# If the block stub's jump is the last code, overwrite the jump with the new code.
@cb.set_write_addr(block_stub.start_addr)
@cb.write(new_asm)
else
# If the block stub's jump is old code, change the jump target to the new code.
new_addr = @cb.write(new_asm)
@cb.with_write_addr(block_stub.start_addr) do
asm = Assembler.new
block_stub.change_block.call(asm, new_addr)
@cb.write(asm)
end
new_addr
end
end
# Compile a branch stub.
# @param branch_stub [RubyVM::MJIT::BranchStub]
# @param cfp `RubyVM::MJIT::CPointer::Struct_rb_control_frame_t`
# @param branch_target_p [TrueClass,FalseClass]
# @return [Integer] The starting address of the compiled branch stub
def branch_stub_hit(branch_stub, cfp, branch_target_p)
# Update cfp->pc for `jit.at_current_insn?`
pc = branch_target_p ? branch_stub.branch_target_pc : branch_stub.fallthrough_pc
cfp.pc = pc
# Prepare the jump target
new_asm = Assembler.new.tap do |asm|
jit = JITState.new(iseq: branch_stub.iseq, cfp:)
compile_block(asm, jit:, pc:, ctx: branch_stub.ctx.dup)
end
# Rewrite the branch stub
if @cb.write_addr == branch_stub.end_addr
# If the branch stub's jump is the last code, overwrite the jump with the new code.
@cb.set_write_addr(branch_stub.start_addr)
Assembler.new.tap do |branch_asm|
if branch_target_p
branch_stub.branch_target_next.call(branch_asm)
else
branch_stub.fallthrough_next.call(branch_asm)
end
@cb.write(branch_asm)
end
# Compile a fallthrough over the jump
if branch_target_p
branch_stub.branch_target_addr = @cb.write(new_asm)
else
branch_stub.fallthrough_addr = @cb.write(new_asm)
end
else
# Otherwise, just prepare the new code somewhere
if branch_target_p
unless @cb.include?(branch_stub.branch_target_addr)
branch_stub.branch_target_addr = @cb.write(new_asm)
end
else
unless @cb.include?(branch_stub.fallthrough_addr)
branch_stub.fallthrough_addr = @cb.write(new_asm)
end
end
# Update jump destinations
branch_asm = Assembler.new
if branch_stub.end_addr == branch_stub.branch_target_addr # branch_target_next has been used
branch_stub.branch_target_next.call(branch_asm)
elsif branch_stub.end_addr == branch_stub.fallthrough_addr # fallthrough_next has been used
branch_stub.fallthrough_next.call(branch_asm)
else
branch_stub.neither_next.call(branch_asm)
end
@cb.with_write_addr(branch_stub.start_addr) do
@cb.write(branch_asm)
end
end
if branch_target_p
branch_stub.branch_target_addr
else
branch_stub.fallthrough_addr
end
end
private
# Callee-saved: rbx, rsp, rbp, r12, r13, r14, r15
# Caller-saved: rax, rdi, rsi, rdx, rcx, r8, r9, r10, r11
#
# @param asm [RubyVM::MJIT::Assembler]
def compile_prologue(asm)
asm.comment('MJIT entry point')
# Save callee-saved registers used by JITed code
asm.push(CFP)
asm.push(EC)
asm.push(SP)
# Move arguments EC and CFP to dedicated registers
asm.mov(EC, :rdi)
asm.mov(CFP, :rsi)
# Load sp to a dedicated register
asm.mov(SP, [CFP, C.rb_control_frame_t.offsetof(:sp)]) # rbx = cfp->sp
# Setup cfp->jit_return
asm.mov(:rax, @leave_exit)
asm.mov([CFP, C.rb_control_frame_t.offsetof(:jit_return)], :rax)
end
# @param asm [RubyVM::MJIT::Assembler]
def compile_block(asm, jit:, pc: jit.iseq.body.iseq_encoded.to_i, ctx: Context.new)
# Mark the block start address and prepare an exit code storage
jit.block = Block.new(pc:)
asm.block(jit.block)
# Compile each insn
iseq = jit.iseq
index = (pc - iseq.body.iseq_encoded.to_i) / C.VALUE.size
while index < iseq.body.iseq_size
insn = self.class.decode_insn(iseq.body.iseq_encoded[index])
jit.pc = (iseq.body.iseq_encoded + index).to_i
case status = @insn_compiler.compile(jit, ctx, asm, insn)
when KeepCompiling
index += insn.len
when EndBlock
# TODO: pad nops if entry exit exists
break
when CantCompile
@exit_compiler.compile_side_exit(jit, ctx, asm)
break
else
raise "compiling #{insn.name} returned unexpected status: #{status.inspect}"
end
end
end
end
end
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