Planned change patch for `mrb_vm_exec()`

[dearblue]

There are over 10 patches and I plan to split them up and do a PR.
Link to patch collection: master...dearblue:mruby:mruby-vm

When all patches are applied, I show how the object code size and stack size used by mrb_vm_exec() changes on several CPU architectures.

The comparison is the result of simply running the compiler from the command line and compiling src/vm.c.
The commit hashes to be compared are ac8846d and 873b8bb.

The filename of the object code is represented by #{revision}-#{gcc-name}-vm.o.

script and compilers

• script

  for rev in ac8846d 873b8bb
  do
    git checkout $rev
  
    for gcc in /usr/local/bin/*-gcc-*.0
    do
      $gcc -Iinclude -Ibuild/host/include -fstack-usage -Os -c -o $rev-$(basename $gcc)-vm.o src/vm.c
    done
  done
  
  size ac8846d*.o 873b8bb*.o | sort -st- -k2
  grep -w mrb_vm_exec ac8846d-*.su 873b8bb-*.su | sort -st- -k2 | awk '{ printf "%3d %-15s %s\n", $2, $3, $1 }'

• list of compilers on my FreeBSD 14.1/amd64

  /usr/local/bin/aarch64-unknown-freebsd14.0-gcc-12.3.0
  /usr/local/bin/arm-none-eabi-gcc-11.3.0
  /usr/local/bin/armv6-gnueabi-freebsd14.0-gcc-12.3.0
  /usr/local/bin/armv7-gnueabi-freebsd14.0-gcc-12.3.0
  /usr/local/bin/avr-gcc-14.1.0
  /usr/local/bin/i386-unknown-freebsd14.0-gcc-12.3.0
  /usr/local/bin/mips-unknown-freebsd14.0-gcc-9.5.0
  /usr/local/bin/mips64-unknown-freebsd14.0-gcc-9.5.0
  /usr/local/bin/powerpc-unknown-freebsd14.0-gcc-12.3.0
  /usr/local/bin/powerpc64-unknown-freebsd14.0-gcc-12.3.0
  /usr/local/bin/riscv32-unknown-elf-gcc-11.3.0
  /usr/local/bin/riscv64-unknown-freebsd14.0-gcc-12.3.0
  /usr/local/bin/sparc64-unknown-freebsd14.0-gcc-9.5.0
  /usr/local/bin/x86_64-unknown-freebsd14.0-gcc-12.3.0
  /usr/local/bin/xtensa-esp32-elf-gcc-5.2.0
  

• result of size ac8846d*.o 873b8bb*.o | sort -st- -k2

     text   data   bss     dec      hex   filename
    36243      0     0   36243   0x8d93   ac8846d-aarch64-unknown-freebsd14.0-gcc-12.3.0-vm.o
    36554      0     0   36554   0x8eca   873b8bb-aarch64-unknown-freebsd14.0-gcc-12.3.0-vm.o
  
    36503      0     0   36503   0x8e97   ac8846d-arm-none-eabi-gcc-11.3.0-vm.o
    35978      0     0   35978   0x8c8a   873b8bb-arm-none-eabi-gcc-11.3.0-vm.o
  
    33879      0     0   33879   0x8457   ac8846d-armv6-gnueabi-freebsd14.0-gcc-12.3.0-vm.o
    32546      0     0   32546   0x7f22   873b8bb-armv6-gnueabi-freebsd14.0-gcc-12.3.0-vm.o
  
    33695      0     0   33695   0x839f   ac8846d-armv7-gnueabi-freebsd14.0-gcc-12.3.0-vm.o
    32362      0     0   32362   0x7e6a   873b8bb-armv7-gnueabi-freebsd14.0-gcc-12.3.0-vm.o
  
    51606      0     0   51606   0xc996   ac8846d-avr-gcc-14.1.0-vm.o
    51474      0     0   51474   0xc912   873b8bb-avr-gcc-14.1.0-vm.o
  
    31754      0     0   31754   0x7c0a   ac8846d-i386-unknown-freebsd14.0-gcc-12.3.0-vm.o
    28735      0     0   28735   0x703f   873b8bb-i386-unknown-freebsd14.0-gcc-12.3.0-vm.o
  
    45592    424     0   46016   0xb3c0   ac8846d-mips-unknown-freebsd14.0-gcc-9.5.0-vm.o
    45920    424     0   46344   0xb508   873b8bb-mips-unknown-freebsd14.0-gcc-9.5.0-vm.o
  
    45392    848     0   46240   0xb4a0   ac8846d-mips64-unknown-freebsd14.0-gcc-9.5.0-vm.o
    45920    848     0   46768   0xb6b0   873b8bb-mips64-unknown-freebsd14.0-gcc-9.5.0-vm.o
  
    33947      0     0   33947   0x849b   ac8846d-powerpc-unknown-freebsd14.0-gcc-12.3.0-vm.o
    35006      0     0   35006   0x88be   873b8bb-powerpc-unknown-freebsd14.0-gcc-12.3.0-vm.o
  
    35639     40     0   35679   0x8b5f   ac8846d-powerpc64-unknown-freebsd14.0-gcc-12.3.0-vm.o
    36594     40     0   36634   0x8f1a   873b8bb-powerpc64-unknown-freebsd14.0-gcc-12.3.0-vm.o
  
    29306      0     0   29306   0x727a   ac8846d-riscv32-unknown-elf-gcc-11.3.0-vm.o
    30382      0     0   30382   0x76ae   873b8bb-riscv32-unknown-elf-gcc-11.3.0-vm.o
  
    31492      0     0   31492   0x7b04   ac8846d-riscv64-unknown-freebsd14.0-gcc-12.3.0-vm.o
    32640      0     0   32640   0x7f80   873b8bb-riscv64-unknown-freebsd14.0-gcc-12.3.0-vm.o
  
    40306      0     0   40306   0x9d72   ac8846d-sparc64-unknown-freebsd14.0-gcc-9.5.0-vm.o
    40226      0     0   40226   0x9d22   873b8bb-sparc64-unknown-freebsd14.0-gcc-9.5.0-vm.o
  
    43734      0     0   43734   0xaad6   ac8846d-x86_64-unknown-freebsd14.0-gcc-12.3.0-vm.o
    38968      0     0   38968   0x9838   873b8bb-x86_64-unknown-freebsd14.0-gcc-12.3.0-vm.o
  
    26361      0     0   26361   0x66f9   ac8846d-xtensa-esp32-elf-gcc-5.2.0-vm.o
    26216      0     0   26216   0x6668   873b8bb-xtensa-esp32-elf-gcc-5.2.0-vm.o
  

• result of grep -w mrb_vm_exec ac8846d-*.su 873b8bb-*.su | sort -st- -k2 | awk '{ printf "%3d %-15s %s\n", $2, $3, $1 }'

  400 static          ac8846d-aarch64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  384 static          873b8bb-aarch64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  248 static          ac8846d-arm-none-eabi-gcc-11.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  216 static          873b8bb-arm-none-eabi-gcc-11.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  216 static          ac8846d-armv6-gnueabi-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  200 static          873b8bb-armv6-gnueabi-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  216 static          ac8846d-armv7-gnueabi-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  200 static          873b8bb-armv7-gnueabi-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  456 dynamic,bounded ac8846d-avr-gcc-14.1.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  474 dynamic,bounded 873b8bb-avr-gcc-14.1.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  576 dynamic,bounded ac8846d-i386-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  624 dynamic,bounded 873b8bb-i386-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  352 static          ac8846d-mips-unknown-freebsd14.0-gcc-9.5.0-vm.su:vm.c:1396:1:mrb_vm_exec
  368 static          873b8bb-mips-unknown-freebsd14.0-gcc-9.5.0-vm.su:vm.c:1405:1:mrb_vm_exec
  
  576 static          ac8846d-mips64-unknown-freebsd14.0-gcc-9.5.0-vm.su:vm.c:1396:1:mrb_vm_exec
  560 static          873b8bb-mips64-unknown-freebsd14.0-gcc-9.5.0-vm.su:vm.c:1405:1:mrb_vm_exec
  
  368 static          ac8846d-powerpc-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  352 static          873b8bb-powerpc-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  656 static          ac8846d-powerpc64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  592 static          873b8bb-powerpc64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  288 static          ac8846d-riscv32-unknown-elf-gcc-11.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  272 static          873b8bb-riscv32-unknown-elf-gcc-11.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  528 static          ac8846d-riscv64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  528 static          873b8bb-riscv64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  832 static          ac8846d-sparc64-unknown-freebsd14.0-gcc-9.5.0-vm.su:vm.c:1396:1:mrb_vm_exec
  800 static          873b8bb-sparc64-unknown-freebsd14.0-gcc-9.5.0-vm.su:vm.c:1405:1:mrb_vm_exec
  
  576 dynamic,bounded ac8846d-x86_64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1396:1:mrb_vm_exec
  656 dynamic,bounded 873b8bb-x86_64-unknown-freebsd14.0-gcc-12.3.0-vm.su:src/vm.c:1405:1:mrb_vm_exec
  
  240 static          ac8846d-xtensa-esp32-elf-gcc-5.2.0-vm.su:vm.c:1396:1:mrb_vm_exec
  240 static          873b8bb-xtensa-esp32-elf-gcc-5.2.0-vm.su:vm.c:1405:1:mrb_vm_exec
  

[dearblue]

The following is the number of CPU cycles measured by valgrind --tool=cachegrind on FreeBSD 14.1/aarch64 before applying the patch and after all commits have been applied.

• number of CPU cycles with valgrind --tool=cachegrind

  ###  cachegrind.report.bm_ao_render.rb (gcc -O3)  ###
           44,067,292,989 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           40,363,551,416 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_app_lc_fizzbuzz.rb (gcc -O3)  ###
          100,314,348,987 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           95,186,415,759 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_fib.rb (gcc -O3)  ###
           37,450,445,816 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           33,167,332,104 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_so_lists.rb (gcc -O3)  ###
            5,382,464,066 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
            5,008,820,848 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_ao_render.rb (gcc -Os)  ###
           61,138,931,508 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           55,300,095,434 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_app_lc_fizzbuzz.rb (gcc -Os)  ###
          132,952,388,251 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
          125,260,868,233 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_fib.rb (gcc -Os)  ###
           55,470,198,609 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           48,160,691,619 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_so_lists.rb (gcc -Os)  ###
            8,454,236,555 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
            7,706,967,077 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  

• stack usage of mrb_vm_exec()

  # gcc -Os
   816 static          /var/tmp/mruby/-Os/ac8846d/build/host/src/vm.su:/var/tmp/mruby/-Os/ac8846d/src/vm.c:1396:1:mrb_vm_exec
   848 static          /var/tmp/mruby/-Os/873b8bb/build/host/src/vm.su:/var/tmp/mruby/-Os/873b8bb/src/vm.c:1405:1:mrb_vm_exec
  
  # gcc -O3
  1296 static          /var/tmp/mruby/-O3/ac8846d/build/host/src/vm.su:/var/tmp/mruby/-O3/ac8846d/src/vm.c:1396:1:mrb_vm_exec
  1200 static          /var/tmp/mruby/-O3/873b8bb/build/host/src/vm.su:/var/tmp/mruby/-O3/873b8bb/src/vm.c:1405:1:mrb_vm_exec
  

• size of bin/mruby

      text   data   bss      dec       hex   filename
  # gcc -Os
    739159   7648    64   746871   0xb6577   /var/tmp/mruby/-Os/ac8846d/build/host/bin/mruby
    737407   7648    64   745119   0xb5e9f   /var/tmp/mruby/-Os/873b8bb/build/host/bin/mruby
  
  # gcc -O3
    991311   8080    64   999455   0xf401f   /var/tmp/mruby/-O3/ac8846d/build/host/bin/mruby
    983327   8080    64   991471   0xf20ef   /var/tmp/mruby/-O3/873b8bb/build/host/bin/mruby
  

[dearblue]

The following are the results of CPU cycles per commit measured by valgrind --tool=cachegrind against FreeBSD 14.1/amd64.

• number of CPU cycles by valgrind --tool=cachegrind

  # gcc -O3
  ###  cachegrind.report.bm_ao_render.rb (-O3)  ###
           48,504,832,392 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           48,242,911,092 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
           47,599,250,059 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
           46,468,037,607 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
           46,365,545,428 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
           46,366,228,713 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
           45,549,758,759 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
           44,938,176,186 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
           45,228,751,355 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
           44,643,188,816 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
           44,598,580,797 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
           44,602,678,178 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
           44,603,232,137 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_app_lc_fizzbuzz.rb (-O3)  ###
          109,983,209,013 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
          109,687,604,225 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
          108,720,856,885 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
          107,362,261,466 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
          107,196,332,623 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
          107,200,998,310 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
          106,705,472,416 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
          105,384,724,695 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
          106,009,039,559 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
          104,764,237,066 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
          104,852,377,842 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
          104,836,239,207 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
          104,840,630,702 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_fib.rb (-O3)  ###
           40,265,431,806 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           40,030,902,455 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
           39,561,843,440 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
           38,696,010,940 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
           38,578,745,971 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
           38,578,745,971 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
           37,562,449,140 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
           36,663,420,192 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
           37,015,214,616 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
           35,920,744,287 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
           35,842,567,779 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
           35,842,567,772 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
           35,842,567,863 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_so_lists.rb (-O3)  ###
            6,303,615,060 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
            6,243,601,501 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
            5,991,554,696 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
            6,012,540,426 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
            6,030,537,900 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
            6,030,537,905 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
            5,928,494,572 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
            5,907,475,775 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
            5,949,489,846 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
            5,970,475,039 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
            5,970,469,793 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
            5,970,469,754 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
            5,970,470,140 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  
  # gcc -Os
  ###  cachegrind.report.bm_ao_render.rb (-Os)  ###
           69,699,622,332 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           69,550,235,049 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
           68,080,741,429 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
           66,988,221,631 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
           66,748,786,095 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
           66,748,663,857 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
           64,141,865,204 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
           63,693,040,474 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
           63,691,793,699 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
           63,354,880,530 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
           63,294,533,181 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
           63,294,441,791 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
           63,296,284,805 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_app_lc_fizzbuzz.rb (-Os)  ###
          152,002,475,134 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
          151,807,875,779 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
          149,404,111,123 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
          148,332,861,203 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
          148,126,005,502 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
          148,124,340,126 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
          145,898,544,952 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
          144,249,148,964 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
          144,254,973,413 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
          143,678,284,506 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
          143,502,153,991 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
          143,496,587,113 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
          143,496,485,083 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_fib.rb (-Os)  ###
           61,099,634,291 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
           60,943,281,183 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
           59,145,221,851 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
           59,859,515,731 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
           59,703,162,179 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
           59,703,162,179 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
           55,442,541,634 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
           54,778,042,002 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
           54,738,953,842 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
           54,230,806,783 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
           54,113,541,600 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
           54,113,541,503 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
           54,191,717,853 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  ###  cachegrind.report.bm_so_lists.rb (-Os)  ###
            9,801,731,864 (100.0%)  PROGRAM TOTALS  ac8846d numeric.c: add Numeric#fdiv
            9,753,721,835 (100.0%)  PROGRAM TOTALS  daa1b55 Doubling the call stack when extending it
            9,273,625,754 (100.0%)  PROGRAM TOTALS  f0f15a1 Added fast-path for positional arguments less than 15 in `OP_SEND`
            9,351,621,673 (100.0%)  PROGRAM TOTALS  fb88906 Perform pseudo binary search with `mrb_type()`
            9,348,615,080 (100.0%)  PROGRAM TOTALS  17e447c Omit error checking at `OP_RETURN`, `OP_RETURN_BLK` and `OP_BREAK`
            9,348,615,084 (100.0%)  PROGRAM TOTALS  34216a5 Assume that `MRB_CATCH()` has `mrb->exc` set
            9,060,477,069 (100.0%)  PROGRAM TOTALS  b055fa5 Remove `pc` and `proc` from `mrb_vm_exec()`
            9,084,466,720 (100.0%)  PROGRAM TOTALS  4e7c100 Removing `pool` and `syms` variables in `mrb_vm_exec()`
            9,081,465,514 (100.0%)  PROGRAM TOTALS  98c12b0 Removing `ch` variables with `mrb_vm_exec()`
            9,084,456,564 (100.0%)  PROGRAM TOTALS  0b5b6c1 Omit confirmation of C function call frames during unwinding
            9,081,453,498 (100.0%)  PROGRAM TOTALS  a6fd41a Cache `ci` in `CHECKPOINT_MAIN()` of `OP_RETURN`
            9,081,453,110 (100.0%)  PROGRAM TOTALS  36030c1 Remove `localjump_error()`
            9,081,453,423 (100.0%)  PROGRAM TOTALS  873b8bb Refactoring the code in `OP_BREAK` and `OP_RETURN_BLK
  

• stack usage of mrb_vm_exec()

  # gcc -Os
   576 dynamic,bounded /var/tmp/mruby/-Os/ac8846d/build/host/src/vm.su:/var/tmp/mruby/-Os/ac8846d/src/vm.c:1396:1:mrb_vm_exec
   576 dynamic,bounded /var/tmp/mruby/-Os/daa1b55/build/host/src/vm.su:/var/tmp/mruby/-Os/daa1b55/src/vm.c:1398:1:mrb_vm_exec
   592 dynamic,bounded /var/tmp/mruby/-Os/f0f15a1/build/host/src/vm.su:/var/tmp/mruby/-Os/f0f15a1/src/vm.c:1398:1:mrb_vm_exec
   592 dynamic,bounded /var/tmp/mruby/-Os/fb88906/build/host/src/vm.su:/var/tmp/mruby/-Os/fb88906/src/vm.c:1398:1:mrb_vm_exec
   592 dynamic,bounded /var/tmp/mruby/-Os/17e447c/build/host/src/vm.su:/var/tmp/mruby/-Os/17e447c/src/vm.c:1407:1:mrb_vm_exec
   592 dynamic,bounded /var/tmp/mruby/-Os/34216a5/build/host/src/vm.su:/var/tmp/mruby/-Os/34216a5/src/vm.c:1407:1:mrb_vm_exec
   656 dynamic,bounded /var/tmp/mruby/-Os/b055fa5/build/host/src/vm.su:/var/tmp/mruby/-Os/b055fa5/src/vm.c:1409:1:mrb_vm_exec
   640 dynamic,bounded /var/tmp/mruby/-Os/4e7c100/build/host/src/vm.su:/var/tmp/mruby/-Os/4e7c100/src/vm.c:1409:1:mrb_vm_exec
   640 dynamic,bounded /var/tmp/mruby/-Os/98c12b0/build/host/src/vm.su:/var/tmp/mruby/-Os/98c12b0/src/vm.c:1411:1:mrb_vm_exec
   640 dynamic,bounded /var/tmp/mruby/-Os/0b5b6c1/build/host/src/vm.su:/var/tmp/mruby/-Os/0b5b6c1/src/vm.c:1427:1:mrb_vm_exec
   640 dynamic,bounded /var/tmp/mruby/-Os/a6fd41a/build/host/src/vm.su:/var/tmp/mruby/-Os/a6fd41a/src/vm.c:1427:1:mrb_vm_exec
   640 dynamic,bounded /var/tmp/mruby/-Os/36030c1/build/host/src/vm.su:/var/tmp/mruby/-Os/36030c1/src/vm.c:1405:1:mrb_vm_exec
   640 dynamic,bounded /var/tmp/mruby/-Os/873b8bb/build/host/src/vm.su:/var/tmp/mruby/-Os/873b8bb/src/vm.c:1405:1:mrb_vm_exec
  
  # gcc -O3
  1280 static          /var/tmp/mruby/-O3/ac8846d/build/host/src/vm.su:/var/tmp/mruby/-O3/ac8846d/src/vm.c:1396:1:mrb_vm_exec
  1280 static          /var/tmp/mruby/-O3/daa1b55/build/host/src/vm.su:/var/tmp/mruby/-O3/daa1b55/src/vm.c:1398:1:mrb_vm_exec
  1408 static          /var/tmp/mruby/-O3/f0f15a1/build/host/src/vm.su:/var/tmp/mruby/-O3/f0f15a1/src/vm.c:1398:1:mrb_vm_exec
  1440 static          /var/tmp/mruby/-O3/fb88906/build/host/src/vm.su:/var/tmp/mruby/-O3/fb88906/src/vm.c:1398:1:mrb_vm_exec
  1520 static          /var/tmp/mruby/-O3/17e447c/build/host/src/vm.su:/var/tmp/mruby/-O3/17e447c/src/vm.c:1407:1:mrb_vm_exec
  1520 static          /var/tmp/mruby/-O3/34216a5/build/host/src/vm.su:/var/tmp/mruby/-O3/34216a5/src/vm.c:1407:1:mrb_vm_exec
  1776 static          /var/tmp/mruby/-O3/b055fa5/build/host/src/vm.su:/var/tmp/mruby/-O3/b055fa5/src/vm.c:1409:1:mrb_vm_exec
  1760 static          /var/tmp/mruby/-O3/4e7c100/build/host/src/vm.su:/var/tmp/mruby/-O3/4e7c100/src/vm.c:1409:1:mrb_vm_exec
  1728 static          /var/tmp/mruby/-O3/98c12b0/build/host/src/vm.su:/var/tmp/mruby/-O3/98c12b0/src/vm.c:1411:1:mrb_vm_exec
  1632 static          /var/tmp/mruby/-O3/0b5b6c1/build/host/src/vm.su:/var/tmp/mruby/-O3/0b5b6c1/src/vm.c:1427:1:mrb_vm_exec
  1648 static          /var/tmp/mruby/-O3/a6fd41a/build/host/src/vm.su:/var/tmp/mruby/-O3/a6fd41a/src/vm.c:1427:1:mrb_vm_exec
  1536 static          /var/tmp/mruby/-O3/36030c1/build/host/src/vm.su:/var/tmp/mruby/-O3/36030c1/src/vm.c:1405:1:mrb_vm_exec
  1536 static          /var/tmp/mruby/-O3/873b8bb/build/host/src/vm.su:/var/tmp/mruby/-O3/873b8bb/src/vm.c:1405:1:mrb_vm_exec
  

• size of bin/mruby

       text   data   bss       dec       hex   filename
  # gcc -Os
     744315   8552    88    752955   0xb7d3b   /var/tmp/mruby/-Os/ac8846d/build/host/bin/mruby
     744299   8552    88    752939   0xb7d2b   /var/tmp/mruby/-Os/daa1b55/build/host/bin/mruby
     744619   8552    88    753259   0xb7e6b   /var/tmp/mruby/-Os/f0f15a1/build/host/bin/mruby
     743707   8552    88    752347   0xb7adb   /var/tmp/mruby/-Os/fb88906/build/host/bin/mruby
     743611   8552    88    752251   0xb7a7b   /var/tmp/mruby/-Os/17e447c/build/host/bin/mruby
     743611   8552    88    752251   0xb7a7b   /var/tmp/mruby/-Os/34216a5/build/host/bin/mruby
     736331   8552    88    744971   0xb5e0b   /var/tmp/mruby/-Os/b055fa5/build/host/bin/mruby
     736251   8552    88    744891   0xb5dbb   /var/tmp/mruby/-Os/4e7c100/build/host/bin/mruby
     736315   8552    88    744955   0xb5dfb   /var/tmp/mruby/-Os/98c12b0/build/host/bin/mruby
     736475   8552    88    745115   0xb5e9b   /var/tmp/mruby/-Os/0b5b6c1/build/host/bin/mruby
     736475   8552    88    745115   0xb5e9b   /var/tmp/mruby/-Os/a6fd41a/build/host/bin/mruby
     736235   8552    88    744875   0xb5dab   /var/tmp/mruby/-Os/36030c1/build/host/bin/mruby
     736235   8552    88    744875   0xb5dab   /var/tmp/mruby/-Os/873b8bb/build/host/bin/mruby
  
  # gcc -O3
    1027422   8544    88   1036054   0xfcf16   /var/tmp/mruby/-O3/ac8846d/build/host/bin/mruby
    1027382   8544    88   1036014   0xfceee   /var/tmp/mruby/-O3/daa1b55/build/host/bin/mruby
    1027206   8544    88   1035838   0xfce3e   /var/tmp/mruby/-O3/f0f15a1/build/host/bin/mruby
    1019158   8544    88   1027790   0xfaece   /var/tmp/mruby/-O3/fb88906/build/host/bin/mruby
    1019382   8544    88   1028014   0xfafae   /var/tmp/mruby/-O3/17e447c/build/host/bin/mruby
    1019382   8544    88   1028014   0xfafae   /var/tmp/mruby/-O3/34216a5/build/host/bin/mruby
    1014886   8544    88   1023518   0xf9e1e   /var/tmp/mruby/-O3/b055fa5/build/host/bin/mruby
    1014598   8544    88   1023230   0xf9cfe   /var/tmp/mruby/-O3/4e7c100/build/host/bin/mruby
    1014582   8544    88   1023214   0xf9cee   /var/tmp/mruby/-O3/98c12b0/build/host/bin/mruby
    1016694   8544    88   1025326   0xfa52e   /var/tmp/mruby/-O3/0b5b6c1/build/host/bin/mruby
    1016598   8544    88   1025230   0xfa4ce   /var/tmp/mruby/-O3/a6fd41a/build/host/bin/mruby
    1016070   8544    88   1024702   0xfa2be   /var/tmp/mruby/-O3/36030c1/build/host/bin/mruby
    1016022   8544    88   1024654   0xfa28e   /var/tmp/mruby/-O3/873b8bb/build/host/bin/mruby
  

[dearblue]

Benchmark results are provided for reference.