[llvm-dev] Where's the optimiser gone? (part 5.a): missed tail calls, and more...

Stefan Kanthak via llvm-dev llvm-dev at lists.llvm.org
Wed Dec 5 03:01:39 PST 2018

"Bruce Hoult" <brucehoult at sifive.com> wrote:

> On Tue, Dec 4, 2018 at 3:58 PM Daniel Sanders via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>> On Dec 4, 2018, at 15:11, Stefan Kanthak <stefan.kanthak at nexgo.de> wrote:
>> No, I understand his intent. I just doesn't align with my intent,
>> including the hoops he/LLVM wants me to jump through.
>> He's not saying they're your bugs, he's just saying they need
>> to be reported in the correct place.
>> Go ahead, report them there!
>> I'm afraid I don't have the time to do that. I have my own work to attend
>> to.
> How uncharitable of you.

I second that!

> Mr Kanthak's time is more valuable than anyone else's.

Nice argument.
Did you come up with this brilliant idea completely on your own?

May I but add another, completely bizarre argument to the discussion:
besides Daniel and me, and even you who wastes his surely precious time
with so very constructive comments, there may be one, two or even three
OTHER people, let's call them "users" of LLVM instead of victims, whose
DEFINITIVELY more valuable time (be it real or CPU) is wasted waiting
for their programs to complete due to the unoptimised code produced by
LLVM, or due to the unoptimised routines shipped with compiler-rt, or
even both, while the web site <https://compiler-rt.llvm.org/> blatantly
lies them in their face stating

| The builtins library provides optimized implementations of this and
| other low-level routines, either in target-independent C form, or as
| a heavily-optimized assembly.

which some of these implementations are clearly NOT!
Now accumulate this time over your user base; don't forget to include
the end users, whose time and resources are wasted running not properly
optimised code generated by or shipped with LLVM.

Speaking of waste: I recommend to dump the executable Windows installer.
It fails here, on properly secured Windows installations, miserably.
And if it would NOT fail, it allows escalation of privilege (CWE-377,
CWE-379, CAPEC-29).

Besides that, I consider dumping several identical files clang*.exe or
*lld*.exe with 40MB size instead of creating hardlinks another waste of
your users resources.

stay tuned
Stefan Kanthak

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