[llvm-commits] [llvm] r172534 - /llvm/trunk/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll

Moving to llvm-dev...

Hi Andy,

I have been able track down the reason for the difference in output
generated by
opt. The difference is caused when the target triple specified in the
is not a supported target for opt/clang/llvm. In this case, opt doesn't thow
error and hence, later in LSR the NoTTI::isLegalAddressingMode is called
results in the different output.

The clang-native-arm build-bot builds clang with ARM being the only
target[1]. This is the reason the failure occured only on this build-bot.
problem can be reproduced on x86-hosted clang, if you only build it with
ARM as the supported target.

I think this problem is responsible for other failures on non-x86

There a few possible solutions to this problem, but I am not sure which one
the right solution:

(a) Error out if *explicitly* specified target-triple is not supported.
   However, this may cause a number of tests to fail on non-X86 hosted
   build-bots as:
   Tests (with explicit target-triple): 1050
   Tests (i686,x86) : 738
   Tests (arm/thumb) : 132
   Tests (powerpc) : 128
   Tests (mips) : 11

(b) Skip tests if *explicitly* specified target-triple is not supported.
   However, this will result in a number of test being skipped on non-x86

(c) Modify the tests to cope with the case when the specified target is not

Let me know what do you think? I would be glad to be involved in defining a
solution in this case. I am happy to open a PR if you think is the best way
resolve this issue.


[1] Configure command:
--disable-bindings --build=armv7l-unknown-linux-gnueabihf
--target=armv7l-unknown-linux-gnueabihf --with-cpu=cortex-a9 --with-fpu=neon
--with-float=hard --enable-targets=arm --without-llvmgcc --without-llvmgxx
--enable-optimized --enable-assertions

Thanks for figuring this out Manish.

It seems to me if you don't bother to build a target, it's fair that you won't benefit from tests designed for that target. When I care about testing a change, I build *all* targets. Conversely if you want a test to be platform independent you shouldn't specify a triple.

However, this may be a naive perspective considering the high percentage of tests with triples living in platform-independent test directories.

I'm moving the thread to llvm-dev because I'm sure someone else has thought about this problem. Hopefully they can tell us what to do...

It wouldn't hurt to open a PR to capture the discussion and decision.