Re: [Tinycc-devel] C99 token pasting
On 12 April 2014 12:23, Thomas Preud'homme robo...@celest.fr wrote: On April 1, 2014 5:22:55 PM GMT+08:00, Jay Foad jay.f...@gmail.com wrote: C99 specifies the behaviour of token pasting when either (or both) of the arguments to be pasted expand to an empty sequence of tokens. tcc doesn't seem to implement this: $ cat p.c #define P(A,B) A ## B bob #define Q(A,B) A ## B+ P(jim,) Q(+,) $ ./tcc -E p.c # 2 p.c p.c:3: warning: pasting jim and does not give a valid preprocessing token jim bob ++ In the P() example, the warning is inappropriate. In the Q() example, the result is wrong. We should get + and + as two separate tokens, not the single token ++. Fixed in mob. Works for me. Thanks! Jay. ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] C99 token pasting
Thomas Preud'homme wrote: On April 12, 2014 9:53:51 PM GMT+08:00, grischka gris...@gmx.de wrote: Good, however note that the mechanism to perform token pasting via tcc_open_bf(tcc_state, :paste:, cstr.size); is extremely slow and per se has a good share in making current tcc about twice as slow compiling itself compared to 0.9.25. You mean even without this patch tcc is already slower than for 0.9.26? No, I meant 0.9.25. ;) However looking more closely the results for the current tcc are more like at ~135% compared to those with 0.9.24/25. Most of that seems due to changes/complications in the preprocessor, such as: http://repo.or.cz/w/tinycc.git/commitdiff/00f093276030ed87c3992a5bde22673f691b08c9 http://repo.or.cz/w/tinycc.git/commitdiff/0f0ed4a8bf2b6f6bdcab1a46c34c6f54005bf34e http://repo.or.cz/w/tinycc.git/commitdiff/44e84bb22adc78844ac1c08e6f8a6d0278a942d8 Your patch would add additional 15-20%: http://repo.or.cz/w/tinycc.git/commitdiff/6e56bb387db8af055ff6de71a23b270de55c3dc8 Also I just noticed it breaks the test case given in http://repo.or.cz/w/tinycc.git/commitdiff/dd5630ff95b8dc47ab3b5ef3f167f3342da79a77 There seems btw a similar patch at http://repo.or.cz/w/tinycc.git/commitdiff/185fba418978aabef36765fdfaf24d516f1a9f33 Now I observe that (in self compilation) token pasting happens 3113 times, however the fix (which as the comment suggests is to improve certain cases of token pasting) runs similar code additional 22669 times. This raises some questions. o_O Strange indeed. I see two ways to reduce the cost of this patch. First one is to rename next_nomacro1 become next_nomacro2 that would take a char * pointer to the buffer to parse for tokens and create a next_nomacro1 wrapper for compatibility. Then tcc_open_bf would not be necessary. It could maybe allow to remove another tcc_open_bf in the same function. A second solution would be to create a new function capable of identifying all the cases where a space needs to be added. That would duplicate part of what next_nomacro1 already know about tokens but should be quite a small function and would be faster. Maybe the first change should be done anyway if choosing the second approach for the already existing call to tcc_open_bf in macro_twosharps. And solution 3 (my favorite): Just hope for someone to rewrite those tiny five macro_subst_stuff functions from scratch altogether, finally. Until then, why not add that space regardless of what token follows (even if it doesn't look exactly like gcc -E). But then only if a ## paste did actually happen and then only in tcc -E mode. Otherwise there is no point to add spaces, they're all removed anyway. --- grischka Thanks for monitoring performance regression grischka. Cheers, Thomas ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] C99 token pasting
Hi Jay, On April 1, 2014 5:22:55 PM GMT+08:00, Jay Foad jay.f...@gmail.com wrote: C99 specifies the behaviour of token pasting when either (or both) of the arguments to be pasted expand to an empty sequence of tokens. tcc doesn't seem to implement this: $ cat p.c #define P(A,B) A ## B bob #define Q(A,B) A ## B+ P(jim,) Q(+,) $ ./tcc -E p.c # 2 p.c p.c:3: warning: pasting jim and does not give a valid preprocessing token jim bob ++ In the P() example, the warning is inappropriate. In the Q() example, the result is wrong. We should get + and + as two separate tokens, not the single token ++. Fixed in mob. Cheers, Thomas ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] C99 token pasting
Thomas Preud'homme wrote: In the P() example, the warning is inappropriate. In the Q() example, the result is wrong. We should get + and + as two separate tokens, not the single token ++. Fixed in mob. Good, however note that the mechanism to perform token pasting via tcc_open_bf(tcc_state, :paste:, cstr.size); is extremely slow and per se has a good share in making current tcc about twice as slow compiling itself compared to 0.9.25. Now I observe that (in self compilation) token pasting happens 3113 times, however the fix (which as the comment suggests is to improve certain cases of token pasting) runs similar code additional 22669 times. This raises some questions. --- grischka ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] C99 token pasting
On April 12, 2014 9:53:51 PM GMT+08:00, grischka gris...@gmx.de wrote: Good, however note that the mechanism to perform token pasting via tcc_open_bf(tcc_state, :paste:, cstr.size); is extremely slow and per se has a good share in making current tcc about twice as slow compiling itself compared to 0.9.25. You mean even without this patch tcc is already slower than for 0.9.26? Now I observe that (in self compilation) token pasting happens 3113 times, however the fix (which as the comment suggests is to improve certain cases of token pasting) runs similar code additional 22669 times. This raises some questions. o_O Strange indeed. I see two ways to reduce the cost of this patch. First one is to rename next_nomacro1 become next_nomacro2 that would take a char * pointer to the buffer to parse for tokens and create a next_nomacro1 wrapper for compatibility. Then tcc_open_bf would not be necessary. It could maybe allow to remove another tcc_open_bf in the same function. A second solution would be to create a new function capable of identifying all the cases where a space needs to be added. That would duplicate part of what next_nomacro1 already know about tokens but should be quite a small function and would be faster. Maybe the first change should be done anyway if choosing the second approach for the already existing call to tcc_open_bf in macro_twosharps. Thanks for monitoring performance regression grischka. Cheers, Thomas ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
[Tinycc-devel] C99 token pasting
C99 specifies the behaviour of token pasting when either (or both) of the arguments to be pasted expand to an empty sequence of tokens. tcc doesn't seem to implement this: $ cat p.c #define P(A,B) A ## B bob #define Q(A,B) A ## B+ P(jim,) Q(+,) $ ./tcc -E p.c # 2 p.c p.c:3: warning: pasting jim and does not give a valid preprocessing token jim bob ++ In the P() example, the warning is inappropriate. In the Q() example, the result is wrong. We should get + and + as two separate tokens, not the single token ++. Jay. ___ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
