Tis-interpreter – find subtle bugs in programs written in standard C

Re:Tis-interpreter – find subtle bugs in programs written in... by __s on Saturday April 09, 2016 @07:27AM (#11460844)

Examples you listed would be better made "implementation defined." ie use RFC language with "Programmers should avoid shifting by more than the bitwidth, compilers should produce an implementation defined result, but may specify a trap in this circumstance"

What's your opinion of What every compiler writer should know about programmers? http://www.complang.tuwien.ac.at/kps2015/proceedings/KPS_201...

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Re:Tis-interpreter – find subtle bugs in programs written in... by PeCaN on Saturday April 09, 2016 @01:47PM (#11462345)

My opinion is that we need a What every programmer should know about compilers essay.

I could take that document more seriously if it didn't make compiler writers out to be evil.

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Re:Tis-interpreter – find subtle bugs in programs written in... by imtringued on Saturday April 09, 2016 @09:34AM (#11461146)

I don't understand why the entire operation has to be undefined behaviour. Why not just say that the bitwidth may be truncated to an undefined number of bits?

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Re:Tis-interpreter – find subtle bugs in programs written in... by __s on Sunday April 10, 2016 @12:26PM (#11466843)

On x86 the shift only looks at the leftmost 5 bits, so 1<<33 is 2. Whereas elsewhere 1<<33 may be 0. It wouldn't be strange if a platform decided to have 1<<33 throw an overflow fault. The key is that this choice should really be up to the platform, not the compiler

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