e$B1sF#$H?=$7$^$9!#e(B
while true; redo; end e$B$Ge(B YARV
e$B$N%3%s%Q%$%k$,;_$^$i$J$/$J$j$^$9!#e(B
$ ./ruby -ve ‘VM::InstructionSequence.compile(“while true; redo; end”)’
ruby 1.9.0 (2007-08-08 patchlevel 0) [i686-linux]
(e$B8G$^$ke(B)
peephole optimization e$B$r;_$a$k$H$A$c$s$H%3%s%Q%$%k$G$-$^$9!#e(B
$ ./ruby -ve ’
VM::InstructionSequence.compile_option = { :peephole_optimization =>
false }
puts VM::InstructionSequence.compile(“while true; redo; end”).disasm
’
ruby 1.9.0 (2007-08-08 patchlevel 0) [i686-linux]
== disasm: <ISeq:@>=================================
== catch table
| catch type: break st: 0002 ed: 0007 sp: 0000 cont: 0007
| catch type: next st: 0002 ed: 0007 sp: 0000 cont: 0004
| catch type: redo st: 0002 ed: 0007 sp: 0000 cont: 0002 |
|---|
0000 jump 4 (
1)
0002 jump 2
0004 jump 2
0006 putnil
0007 leave
e$B8+$?46$8e(B iseq_peephole_optimize e$B$Ne(B goto again;
e$B$GL58B%k!<%W$7$F$$$k$h$&$G$9!#e(B
e$B@5$7$$=$@5$+$o$+$j$^$;$s$,!"$H$j$"$($:0J2<$GF0$/$h$&$K$J$j$^$7$?!#e(B
Index: compile.c
— compile.c (revision 12903)
+++ compile.c (working copy)
@@ -1318,8 +1318,10 @@
REMOVE_ELEM(&iobj->link);
}
else if (iobj != diobj && diobj->insn_id == BIN(jump)) {
-
OPERAND_AT(iobj, 0) = OPERAND_AT(diobj, 0); -
goto again;
-
if (OPERAND_AT(iobj, 0) != OPERAND_AT(diobj, 0)) { - OPERAND_AT(iobj, 0) = OPERAND_AT(diobj, 0);
- goto again;
-
}}
else if (diobj->insn_id == BIN(leave)) {
/*