Goog test-cases for a new register allocator

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1

Hi,

As I mentioned some time ago on the mailing list, I'm working on the
implementation of the Sarkar's Extended Linear Scan algorithm for LLVM.

For testing and debugging of this algorithm, I need some good
test-cases that check different functionalities of the register
allocator, e.g.:
- test-cases involving a lot of spilling
- test-cases using pre-colored registers, e.g. like the EAX register
used by the division instruction on X86
- test-cases making use of different (partially aliasing)
register-classes at the same-time
- test-cases where the caller-save vs callee-save choices of registers
play a big role.
  
I think these requirements are not specific for my allocator only, but
are important for checking any register allocator. May be someone
(Fernando? David? Evan?) who was working on register allocators has
found a good set of examples covering some of the topics? Or may be
someone knows good examples due to the fact that current register
allocators perform too bad on it? :wink:

Any help and ideas are appreciated!

Thanks,
- Roman

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2

Hey, Roman,

     I have some tests that I used to debug my allocator. I will send them to you in a separate e-mail.

best,

Fernando

3

Hi,

As I mentioned some time ago on the mailing list, I'm working on the
implementation of the Sarkar's Extended Linear Scan algorithm for LLVM.

Cool!

For testing and debugging of this algorithm, I need some good
test-cases that check different functionalities of the register
allocator, e.g.:
- test-cases involving a lot of spilling
- test-cases using pre-colored registers, e.g. like the EAX register
used by the division instruction on X86
- test-cases making use of different (partially aliasing)
register-classes at the same-time
- test-cases where the caller-save vs callee-save choices of registers
play a big role.

I think these requirements are not specific for my allocator only, but
are important for checking any register allocator. May be someone
(Fernando? David? Evan?) who was working on register allocators has
found a good set of examples covering some of the topics? Or may be
someone knows good examples due to the fact that current register
allocators perform too bad on it? :wink:

I've found the NAS Parallel Benchmarks to be quite a good workout:

They are medium-sized benchmarks, so substantial without being totally
overwhelming. They manifest pretty much all of your points above. The
basic linear scan algorithm seems to do fairly well on them so it makes
for a good comparison.

I use version 2.3, the serial flavor (yes, I understand the irony :slight_smile: ).

                                                 -Dave

4

Of course, this is with our optimizer, which does an amazingly good job
of creating register pressure. :slight_smile:

YMMV.

                                                   -Dave

5

Could these be added to llvm-test?

-Chris

6

I just added the two C benchmarks as MultiSource/Benchmarks/NPB-serial.

--Owen

7

Nice, thanks!

-Chris

8

I just added the two C benchmarks as MultiSource/Benchmarks/NPB-serial.

Since llvm-gcc can compile fortran now, how about adding the rest of
the benchmarks too?

Ciao,

Duncan.

9

Hi everyone,

Thanks for all answers, proposals and test-cases I got for testing my
Extended Linear Scan register allocator.

Special thanks to Fernando and David for providing very concrete
test-cases and scripts!

-Roman

--- David Greene <dag@cray.com> schrieb: