On Saturday, February 14, 2015 at 8:07:59 AM UTC+1, Clifford Wolf wrote:
> My default is -Os without the other options. With that I get a JavaScript
> function with 10530 local variables.
>
I have now done a little more analysis over my project. This is not even
the function with the most local variables, there are two larger ones. One
with 12919 and one with 16594 variables:
<skipping first 4979 results>
4302
__ZN12_GLOBAL__N_114dump_cell_exprERNSt3__113basic_ostreamIcNS0_11char_traitsIcEEEENS0_12basic_stringIcS3_NS0_9allocatorIcEEEEPN5Yosys5RTLIL4CellE
4554 __Z24frontend_verilog_yyparsev
4592
__ZN12_GLOBAL__N_110ExposePass7executeENSt3__16vectorINS1_12basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEENS6_IS8_EEEEPN5Yosys5RTLIL6DesignE
4700 __ZN12_GLOBAL__N_110BtorDumper9dump_cellEPKN5Yosys5RTLIL4CellE
5023 __ZN5Yosys3AST7AstNode8genRTLILEib
5212
__ZN12_GLOBAL__N_113TechmapWorker14techmap_moduleEPN5Yosys5RTLIL6DesignEPNS2_6ModuleES4_RNSt3__13setIPNS2_4CellENS7_4lessISA_EENS7_9allocatorISA_EEEERKNS7_3mapINS2_8IdStringENS8_ISI_NS2_14sort_by_id_strENSD_ISI_EEEENSB_ISI_EENSD_INS7_4pairIKSI_SL_EEEEEEb
5512
__ZN12_GLOBAL__N_112replace_cellEPN5Yosys5RTLIL4CellERKNS_7rules_tERKNS4_6bram_tERKNS4_7match_tERNS0_7hashlib4dictINSt3__112basic_stringIcNSF_11char_traitsIcEENSF_9allocatorIcEEEEiNSD_8hash_opsISL_EEEEi
10604 __ZN5Yosys3AST7AstNode8simplifyEbbbiibb
12919 __ZN5Yosys6SatGen10importCellEPNS_5RTLIL4CellEi
16594
__ZN12_GLOBAL__N_119replace_const_cellsEPN5Yosys5RTLIL6DesignEPNS1_6ModuleEbbbbb
0 - 100 vars: 4270 functions
100 - 200 vars: 365 functions
200 - 500 vars: 188 functions
500 - 1000 vars: 76 functions
1000 - 2000 vars: 51 functions
2000 - 5000 vars: 33 functions
5000 - 10000 vars: 3 functions
10000 - 16594 vars: 3 functions
(the difference in number of variables for the simply() function is most
likely because I am now using a script to count, before it was just doing
some hacks in my text editor..)
The frontend_verilog_yyparse at 4554 variables is a parser generated with
bison. So whatever that looks like should not be too uncommon in larger
projects. (But I'm not sure how many of those are ported to JavaScript. ;)
On Saturday, February 14, 2015 at 5:44:36 AM UTC+1, Alon Zakai wrote:
>
> 7044 local variables? wow! :) Is this on an unoptimized build, or -O1? I
> would be surprised to see that on -O2 or -O3.
>
So either I am doing something fundamentally wrong in my project or
functions with thousands of local javascript variables is something one
just gets on occasion..
Under what circumstances does emcc create additional local variables? I
would have assumed that the number local variables would rather be in the
order of number of register you'd usually have in a CPU.. I'm thankful for
any insights or pointers to documentation. (I haven't found any
documentation on those implementation details, but maybe I was just looking
in the wrong places..).
What this functions in my list above all have in common is that they are
rather large, usually built around one large switch statement or series of
if-statements. The sourcecode to the two functions with the most javascript
vars (importCell and replace_cost_cells) can be found here, just an case
anyone is curious:
https://github.com/cliffordwolf/yosys/blob/bc86b4a7e9c847180e6fd7ed81e0a15d5aee00a0/kernel/satgen.h
https://github.com/cliffordwolf/yosys/blob/a8f4a099b5f1c51ccd46d875c874bbb1e7e5766b/passes/opt/opt_const.cc
regards,
- clifford
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