https://github.com/seyko2/tinycc/commit/f2d7cc6db2a4a4f5d943137f18568a6260faadbb

A constant expression removed from the loop.
If subroutine have 50000+ local variables, then currently
compilation of such code takes obly 15 sec. Was 2 min.
gcc-4.1.2 compiles such code in 7 sec. pcc -- 3.44 min.

I was able to run your TCC branch, and your TCC branch with your patches and compare with upstream.

number_of_variables = 50000
number_of_local_variable_access = 50000

- TCC upstream: 110-115 seconds
- your seyko2/github TCC branch: 131-132 seconds
- your seyko2/github TCC branch with the patch: 9.0 seconds
- your seyko2/github TCC branch and TCC upstream without the incompatible types redefinition check (the "if" block is just completely commented out): 0.24-0.32 seconds (!)
- GCC 5.3: 5.7 seconds

Note that your upstream branch is slower than TCC upstream (mob) for some reason. I don't have any idea why it is like that since once I comment out the "if" block, the performance is almost the same (0.24 vs 0.26 seconds).

While your patch significantly improved the situation if you compare it to GCC, however, it seems that the compilation option like you suggested (-fno-type-redefinition-check) might be still very useful - 9.0 vs 0.3 seconds is a noticeable speed-up.

By the way, the patch breaks upstream TCC compilation due to the collision in TOK_HASH_INIT macros:

gcc -o x86_64-tcc tcc.c -DONE_SOURCE -DTCC_TARGET_X86_64 -I.  -Wall -g -O0 -Wdeclaration-after-statement -Wno-deprecated-declarations -Wno-strict-aliasing -Wno-pointer-sign -Wno-sign-compare -Wno-unused-result -Wno-uninitialized -fno-strict-aliasing -lm -ldl
In file included from libtcc.c:38:0,
                 from tcc.c:22:
tccgen.c: In function 'sym_push2':
tccpp.c:410:23: error: called object is not a function or function pointer
 #define TOK_HASH_INIT 1
                       ^
tccgen.c:182:9: note: in expansion of macro 'TOK_HASH_INIT'
         TOK_HASH_INIT(h);
         ^
tccpp.c:411:29: warning: statement with no effect [-Wunused-value]
 #define TOK_HASH_FUNC(h, c) ((h) + ((h) << 5) + ((h) >> 27) + (c))
                             ^
tccgen.c:184:13: note: in expansion of macro 'TOK_HASH_FUNC'
             TOK_HASH_FUNC(h, c);
             ^
In file included from libtcc.c:39:0,
                 from tcc.c:22:
tccgen.c:185:9: warning: implicit declaration of function 'TOK_HASH_FINISH' [-Wimplicit-function-declaration]
         TOK_HASH_FINISH(h);
         ^

timing with 01-types-redefinition.patch
 gcc-4.1.2 -- 8 sec
 tcc       -- 14.4 sec


(file #37054)

> + number_of_local_variable_access = 50000
> - TCC: 110 seconds (almost 2 minutes)
> - GCC: 5.6 seconds

gcc-4.1.2 Yes, 8 seconds
gcc-3.4.6 No, I don't know how long it will to compile this. More then 4 minutes. 1 hour? I don't have time to check.

> However, if I comment the block for checking "incompatible types > for redefinition" in tccgen.c:168 (http://repo.or.cz/tinycc.git
> /blob/HEAD:/tccgen.c#l168), the compilation time drops to 3
> seconds!

May be an option like -fno-type-redefinition-check ?
PS: what you suggested for the option name?

And where is the file?
A code snippet of the tccgen.c is welcom too (location may change)