Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 21 Nov 2023 09:23:08 -0800 | Subject | Re: [PATCH 2/2] zstd: Backport Huffman speed improvement from upstream |
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On Mon, 20 Nov 2023 at 16:52, Nick Terrell <nickrterrell@gmail.com> wrote: > > +/* Calls X(N) for each stream 0, 1, 2, 3. */ > +#define HUF_4X_FOR_EACH_STREAM(X) \ > + { \ > + X(0) \ > + X(1) \ > + X(2) \ > + X(3) \ > + } > + > +/* Calls X(N, var) for each stream 0, 1, 2, 3. */ > +#define HUF_4X_FOR_EACH_STREAM_WITH_VAR(X, var) \ > + { \ > + X(0, (var)) \ > + X(1, (var)) \ > + X(2, (var)) \ > + X(3, (var)) \ > + } > +
What shitty compilers do you need to be compatible with?
Because at least for Linux, the above is one single #define:
#define FOUR(X,y...) do { \ X(0,##y); X(1,##y); X(2,##y); X(3,##y); \ } while (0)
and it does the right thing for any number of arguments, ie
FOUR(fn) FOUR(fn1,a) FOUR(fn2,a,b)
expands to
do { fn(0); fn(1); fn(2); fn(3); } while (0) do { fn1(0,a); fn1(1,a); fn1(2,a); fn1(3,a); } while (0) do { fn2(0,a,b); fn2(1,a,b); fn2(2,a,b); fn2(3,a,b); } while (0)
so unless you need to support some completely garbage compiler upstream, please just do the single #define.
Linus
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