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It's really cool to see how slow unoptimised C is. You get so used to seeing C easily beat any other language in performance that you assume it's really just in

It's really cool to see how slow unoptimised C is. You get so used to seeing C easily beat any other language in performance that you assume it's really just intrinsic to the language. The benchmark shows a SQLite3 unoptimised build 12x slower for CCC, 20x for optimised build. That's enormous! I'm not dissing CCC here, rather I'm impressed with how much speed is squeezed out by GCC out of what is assumed to be already an intrinsically fast language.

kingstnap 8mo ago
The speed of C is still largely intrinsic to the language. The primatives are directly related to the actual silicon. A function call is actually going to turn into a call instruction (or get inlined). The order of bytes in your struct are how they exist in memory, etc. A pointer being dereferenced is a load/store. The converse holds as well. Interpreted languages are slow because this association with the hardware isn't the case. When you have a poopy compiler that does lots of register shuffling then you loose this association. Specifically the constant spilling with those specific functions functions that were the 1000x slowdown, makes the C code look a lot more like Python code (where every variable is several dereference away).
- rich_sasha 8mo ago
  Right - maybe we're saying the same thing. C is naturally amenable to being blazing fast, but if you compile it without trying to be efficient (not trying to be inefficient, just do the simplest, naive thing) it's still slow - by 1-1.5 order of magnitude.
MobiusHorizons 8mo ago
I mean you can always make things slower. There are lots of non-optimizing or low optimizing compilers that are _MUCH_ faster than this. TCC is probably the most famous example, but hardly the only alternative C compiler with performance somewhere between -O1 and -O2 in GCC. By comparison as I understand it, CCC has performance worse than -O0 which is honestly a bit surprising to me, since -O0 should not be a hard to achieve target. As I understand it, at -O0 C is basically just macro expanding into assembly with a bit of order of operations thrown in. I don't believe it even does register allocation.

kingstnap 8mo ago

The speed of C is still largely intrinsic to the language. The primatives are directly related to the actual silicon. A function call is actually going to turn into a call instruction (or get inlined). The order of bytes in your struct are how they exist in memory, etc. A pointer being dereferenced is a load/store. The converse holds as well. Interpreted languages are slow because this association with the hardware isn't the case. When you have a poopy compiler that does lots of register shuffling then you loose this association. Specifically the constant spilling with those specific functions functions that were the 1000x slowdown, makes the C code look a lot more like Python code (where every variable is several dereference away).

rich_sasha 8mo ago
Right - maybe we're saying the same thing. C is naturally amenable to being blazing fast, but if you compile it without trying to be efficient (not trying to be inefficient, just do the simplest, naive thing) it's still slow - by 1-1.5 order of magnitude.

MobiusHorizons 8mo ago

I mean you can always make things slower. There are lots of non-optimizing or low optimizing compilers that are _MUCH_ faster than this. TCC is probably the most famous example, but hardly the only alternative C compiler with performance somewhere between -O1 and -O2 in GCC. By comparison as I understand it, CCC has performance worse than -O0 which is honestly a bit surprising to me, since -O0 should not be a hard to achieve target. As I understand it, at -O0 C is basically just macro expanding into assembly with a bit of order of operations thrown in. I don't believe it even does register allocation.