output.txt

for +=

irb(main):001:0> puts RubyVM::InstructionSequence.compile("x += 1").disasm
== disasm: #<ISeq:<compiled>@<compiled>>================================
local table (size: 2, argc: 0 [opts: 0, rest: -1, post: 0, block: -1, kw: -1@-1, kwrest: -1])
[ 2] x          
0000 trace            1                                               (   1)
0002 getlocal_OP__WC__0 2
0004 putobject_OP_INT2FIX_O_1_C_ 
0005 opt_plus         <callinfo!mid:+, argc:1, ARGS_SIMPLE>, <callcache>
0008 dup              
0009 setlocal_OP__WC__0 2
0011 leave            
=> nil

same as -=

irb(main):002:0> puts RubyVM::InstructionSequence.compile("x -= 1").disasm
== disasm: #<ISeq:<compiled>@<compiled>>================================
local table (size: 2, argc: 0 [opts: 0, rest: -1, post: 0, block: -1, kw: -1@-1, kwrest: -1])
[ 2] x          
0000 trace            1                                               (   1)
0002 getlocal_OP__WC__0 2
0004 putobject_OP_INT2FIX_O_1_C_ 
0005 opt_minus        <callinfo!mid:-, argc:1, ARGS_SIMPLE>, <callcache>
0008 dup              
0009 setlocal_OP__WC__0 2
0011 leave            
=> nil
irb(main):004:0> 

but different for ||= 

irb(main):003:0> puts RubyVM::InstructionSequence.compile("x ||= 1").disasm
== disasm: #<ISeq:<compiled>@<compiled>>================================
local table (size: 2, argc: 0 [opts: 0, rest: -1, post: 0, block: -1, kw: -1@-1, kwrest: -1])
[ 2] x          
0000 trace            1                                               (   1)
0002 getlocal_OP__WC__0 2
0004 dup              
0005 branchif         12
0007 pop              
0008 putobject_OP_INT2FIX_O_1_C_ 
0009 dup              
0010 setlocal_OP__WC__0 2
0012 leave            
=> nil