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flohofwoe · 2024-03-06 08:18:22

This is mostly only true for modern optimising C compilers. If you take a simple C compiler from the 90's, or disable optimisations in a modern compiler, there's a near 1:1 relationship between the C code and compiler output.

muyuu | karma 2824 | avg karma 1.79 · | 2014-10-30 21:00:24

Not necessarily true, although C compilers are usually very good.

SnowHill9902 | karma 685 | avg karma 1.37 · | 2022-04-08 21:05:05

That’s more about the compiler than C.

swiley | karma 10155 | avg karma 1.92 · | 2021-05-20 16:10:33

Are you arguing that e.g. Turbo C and friends from the 80s were higher quality than modern C compilers?

journalctl | karma 1027 | avg karma 3.09 · | 2019-10-17 16:01:43

Unless you’ve written a modern, optimizing C/C++ compiler, you have absolutely no idea what kind of machine code a complex program is going to spit out. It’s not 1972 anymore, and C code is no longer particularly close to the metal. It hasn’t been for some time.

Joky | karma 850 | avg karma 2.12 · | 2015-06-29 16:08:40

Isn't it that if you write standard compliant C code, much less compilers come into the picture ;)

pjmlp | karma 109153 | avg karma 1.76 · | 2016-02-17 07:14:00+00:00

C compiler performance in the 80's for home micros was so bad, that functions were basically naked entry points to full inline Assembly.

And here we are now discussing how good modern C compilers are.

If there isn't the willingness to spend the money to optimize performance, of course it won't improve.

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pjmlp | karma 109153 | avg karma 1.76 · | 2022-04-25 13:42:34

Even with C it only looks like it, if one sticks mainly with a specific compiler and OS.

khedoros1 | karma 2911 | avg karma 1.53 · | 2017-12-13 22:06:48+00:00

Yesteryear's C compilers weren't great, optimization-wise. But anything remotely modern would just brute force its way through a DOS-era program, well optimized or not.

vinceguidry | karma 12286 | avg karma 2.49 · | 2014-11-06 15:18:35+00:00

So, what you're saying is that C is (usually) compiled?

gsnedders | karma 6022 | avg karma 2.57 · | 2013-09-16 12:08:49

Or that your compiler produces code equivalent to the (proven) correct C.

Annatar | karma 6 | avg karma 0.0 · | 2018-08-28 20:13:33

Well we disagree vehemently: writing clean C code that compiles with any ANSI C compiler is pretty damn easy. Take BIND for example, a non-trivial piece of software which compiles with any compiler.

gnulinux | karma 6001 | avg karma 2.75 · | 2019-03-19 13:39:47+00:00

Does compiling to C-- have any benefits compared to compiling equivalent C code (maybe a subset of C)? My guess would be modern C compilers, powered by decades of R&D and programming, would be able to optimize just as well and possibly better.

EDIT: One advantage that comes to my mind is that compiling to C-- will give slightly more power to deal with stack. E.g. implementing exceptions, continuations etc would be simpler. This is possible in C using inline assembly.

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agumonkey | karma 29727 | avg karma 1.44 · | 2015-05-04 07:32:29

Can you really map gcc output to your C code ? With all the optimizations (CF, CSE, RA, ...) the assembly code can vary dramatically (from what I recall from compilation classes at least)

shzhdbi09gv8ioi | karma 376 | avg karma 1.84 · | 2024-01-04 08:42:59

The classic C compilers were known for producing horribly unoptimized code.

It took many years of compiler progress to change C into the performant language we all know and love/hate today.

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umanwizard | karma 14757 | avg karma 2.5 · | 2018-05-01 16:17:51+00:00

Their comment makes sense if you interpret "the C compiler" to mean "mainstream C compilers that 99% people use in production" or even just "gcc and clang".

We're talking about concrete things in the real world here, not philosophizing about the language spec.

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chadcmulligan | karma 2776 | avg karma 2.24 · | 2016-09-07 01:39:38

C compilers

pjmlp | karma 109153 | avg karma 1.76 · | 2016-06-08 06:29:22

Also many that praise C's performace, tend to forget that once upon a time, hobby Z80, 6052, 80x86, 68000 programmers in home micros could write better code than C compilers were able to generate.

So there are a few decades of engineering time spent improving code generation of C compilers.

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jokoon | karma 3945 | avg karma 1.05 · | 2017-12-02 14:24:55

Well I find it more interesting...

Also C compilers can do a lot of micro optimizations that are not trivial, so compiling something to C or maybe LLIR seems like a better choice.

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tptacek | karma 394296 | avg karma 6.04 · | 2011-09-14 17:04:18

I wonder if the author would be surprised by how many language compilers have targeted C for their output.