[Bug #21644] compile.c: fix newrange INSN peephole optimization for chilled string#14879
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nobu merged 1 commit intoruby:masterfrom Oct 20, 2025
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newrange INSN peephole optimization for chilled stringnewrange INSN peephole optimization for chilled string
… chilled string ref: https://bugs.ruby-lang.org/issues/21644 ```shell $ ruby -v -e '("a" || "b").."c"' ruby 3.4.7 (2025-10-08 revision 7a5688e) +PRISM [x86_64-linux] -e:1: warning: possibly useless use of .. in void context -e:1: [BUG] Stack consistency error (sp: 7, bp: 6) ruby 3.4.7 (2025-10-08 revision 7a5688e) +PRISM [x86_64-linux] -- Control frame information ----------------------------------------------- c:0002 p:0013 s:0007 e:000005 EVAL -e:1 [FINISH] c:0001 p:0000 s:0003 E:001920 DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- -e:1:in '<main>' -- Threading information --------------------------------------------------- Total ractor count: 1 Ruby thread count for this ractor: 1 -- C level backtrace information ------------------------------------------- ruby/3.4.7/lib/libruby.so.3.4(rb_print_backtrace+0x8) [0x78aa9573c882] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_dump.c:823 ruby/3.4.7/lib/libruby.so.3.4(rb_vm_bugreport) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_dump.c:1155 ruby/3.4.7/lib/libruby.so.3.4(rb_bug_without_die_internal+0x6b) [0x78aa9544c62f] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/error.c:1097 ruby/3.4.7/lib/libruby.so.3.4(rb_bug) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/error.c:1115 ruby/3.4.7/lib/libruby.so.3.4(vm_stack_consistency_error+0x1f) [0x78aa9544f091] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_insnhelper.c:6523 ruby/3.4.7/lib/libruby.so.3.4(vm_get_cref) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/insns.def:1134 ruby/3.4.7/lib/libruby.so.3.4(vm_setclassvariable) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_insnhelper.c:1630 ruby/3.4.7/lib/libruby.so.3.4(vm_setclassvariable) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm_insnhelper.c:1627 ruby/3.4.7/lib/libruby.so.3.4(vm_exec_core) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/insns.def:253 ruby/3.4.7/lib/libruby.so.3.4(vm_exec_loop+0xa) [0x78aa95724959] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm.c:2622 ruby/3.4.7/lib/libruby.so.3.4(rb_vm_exec) /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/vm.c:2598 ruby/3.4.7/lib/libruby.so.3.4(rb_ec_exec_node+0xa5) [0x78aa95525695] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/eval.c:281 ruby/3.4.7/lib/libruby.so.3.4(ruby_run_node+0x83) [0x78aa95529333] /tmp/ruby-build.20251010151551.31019.jR04SY/ruby-3.4.7/eval.c:319 ruby/3.4.7/bin/ruby(rb_main+0x21) [0x59d86f5e0186] ./main.c:43 ruby/3.4.7/bin/ruby(main) ./main.c:68 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_call_main+0x7a) [0x78aa9502a1ca] ../sysdeps/nptl/libc_start_call_main.h:58 /lib/x86_64-linux-gnu/libc.so.6(call_init+0x0) [0x78aa9502a28b] ../csu/libc-start.c:360 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main_impl) ../csu/libc-start.c:347 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main) (null):0 [0x59d86f5e01d5] ``` The optimization in question: https://github.com/ruby/ruby/blob/957c832db137e67289e93dfd9fd9e915b1f2fc87/compile.c\#L3453-L3480 Before entering the `newrange` optimization, the iseq looks like this: ``` == disasm: #<ISeq:<compiled>@<compiled>:1 (1,0)-(1,17)> 0000 putchilledstring "a" ( 1)[Li] 0002 dup 0003 branchif 8 0005 pop 0006 putchilledstring "b" 0008 putchilledstring "c" 0010 newrange 0 0012 leave ``` So the optimization constructs a new range using the wrong operands (`"b"` and `"c"` instead of `"a"` and `"c"`). I tried to fix this by checking whether the two previous instructions are labeled.
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The optimization in question:
ruby/compile.c
Lines 3453 to 3480 in 957c832
Before entering the
newrangeoptimization, the iseq looks like this:So the optimization constructs a new range using the wrong operands (
"b"and"c"instead of"a"and"c").I tried to fix this by checking whether the two previous instructions are labeled,
but it might be possible to simply apply the same optimization for chilled strings -- the one that transforms(won't work since"a" || "b"into"a"for both frozen and unfrozen stringsdef f = if rand > 0.5 then "a" else "_" end; (f || "x").."y"leads to a fatal error too)