[Octave-bug-tracker] [bug #51574] Build failure with --enable-jit with LLVM 3.8

[Julien Bect]

Follow-up Comment #3, bug #51574 (project octave):

I just found out that, in its present state, my patched version of stable is
only able to jit one for loop, but not two of them...

Consider for instance the attached additional test function test_pisum2.m.  So
now we have two very similar test functions, names test_pisum and
test_pisum2.


octave:1> jit_enable (1)

octave:2> tic;  z = test_pisum (),  toc
z =  1.6448
Elapsed time is 0.059464 seconds.

octave:3> tic;  z = test_pisum2 (),  toc
z =  1.2021
Elapsed time is 15.2592 seconds.

octave:4> tic;  z = test_pisum (),  toc
z =  1.6448
Elapsed time is 0.024164 seconds.


The jit is able to optimize the first for loop, but ignores the second one.

And the results are reversed if I call test_pisum2 first:


octave:1> jit_enable (1)

octave:2> tic;  z = test_pisum2 (),  toc
z =  1.2021
Elapsed time is 0.052254 seconds.

octave:3> tic;  z = test_pisum (),  toc
z =  1.6448
Elapsed time is 11.835 seconds.

octave:4> tic;  z = test_pisum2 (),  toc
z =  1.2021
Elapsed time is 0.019443 seconds.


Obviously, there is something wrong... I have to understand better what is
really going on.

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