Optimizations in C++ Compilers
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Optimizations in C++ Compilers
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Re: Optimizations in C++ Compilers
#2> I went home that evening and created Compiler Explorer.
Nice try. You can’t escape being known as a verb now.
Everyone knows the tool as godbolt.
Re: Optimizations in C++ Compilers
#3> I went home that evening and created Compiler Explorer. Nice try. You can’t escape being known as a verb now. Everyone knows the tool as godbolt.
Interesting tool I've never used, for the uninitiated:
Re: Optimizations in C++ Compilers
#4> I went home that evening and created Compiler Explorer. Nice try. You can’t escape being known as a verb now. Everyone knows the tool as godbolt.
Yep, it honestly never occurred to me that the name of the tool wasn't godbolt. I just went to the site and noticed "Compiler Explorer" for the first time, which seems so generic that I never thought of it as a name.
Re: Optimizations in C++ Compilers
#5> I went home that evening and created Compiler Explorer. Nice try. You can’t escape being known as a verb now. Everyone knows the tool as godbolt.
Yes, it is somehow also an awesome name for a tool.
Re: Optimizations in C++ Compilers
#6Compiler Explorer (aka godbolt) is awesome; I use it at least weekly.
It's amazing how many more code generation questions occur to me now that there's so much less friction in getting the answers.
Re: Optimizations in C++ Compilers
#7> I went home that evening and created Compiler Explorer. Nice try. You can’t escape being known as a verb now. Everyone knows the tool as godbolt.
That's my first impression, too, until I'm curious about what 'godbolt' means, and I googled it...
Re: Optimizations in C++ Compilers
#8Godbolt sounds like a top quality brand of quidditch broom :-D
Re: Optimizations in C++ Compilers
#9> Tail call removal. A recursive function that ends in a call to itself can often be rewritten as a loop, reducing call overhead and reducing the chance of stack overflow.
Most important: this optimization enables pipelined execution.
When people talk about a CPU executing an integer add instruction in ~1 cycle, what they actually mean is that the add has this latency when the CPU pipelines are full.
If you have an 11 stage pipeline... the add can often have a latency of ~11 cycles... if you write the _right_ code for it.
Re: Optimizations in C++ Compilers
#10> Tail call removal. A recursive function that ends in a call to itself can often be rewritten as a loop, reducing call overhead and reducing the chance of stack overflow. Most important: this optimization enables pipelined execution. When people talk about a CPU executing an integer add instruction in ~1 cycle, what they actually mean is that the add has this latency when the CPU pipelines are full. If you have an 1…
FWIW, at least on intel cpu call instructions are fully pipelined and effectively zero latency (although, like all jump instructions there is a limit of one call every other cycle).