[PATCH] Fix LTO handling of module-level assembly (Bug 14152)

[Peter Collingbourne]

Hi Tom,

I don't think that is the correct way to write the test, for a couple
of reasons:

- The test will fail if 'ld' is not gold on the user's system.
- The test will not run on non-Linux systems.

What I would suggest doing is writing a small command line test harness
for the libLTO library, using the API defined in include/llvm-c/lto.h.
The test harness could have a command line interface along the
lines of:

$ lto-test -o foo.o foo1.bc foo2.bc  # Link foo1.bc and foo2.bc to produce foo.o

You could then use lto-test from your lit test, instead of ld.

Peter

On Mon, Sep 16, 2013 at 01:17:09PM -0700, Tom Roeder wrote:
> Here's a patch that adds the test in LLVM IR to test/tools/lto with a
> lit.local.cfg that checks if LTO is present. Also, the check for LTO
> seems wrong to me in test/Makefile: it looks like it's checking to see
> if -flto is in the command-line flags for the current build (rather
> than -flto being possible with the compiler that was built). This
> patch changes that to look for LLVMgold.so in the lib directory.  No
> other tests seem to be using the flag lto_is_enabled at the moment.
> Please let me know what you think.
> 
> Tom
> 
> On Fri, Sep 13, 2013 at 5:30 PM, Tom Roeder <tmroeder at google.com> wrote:
> > OK, thanks. I'll figure out another place to put it.
> >
> > On Sep 13, 2013 5:05 PM, "Bill Wendling" <wendling at apple.com> wrote:
> >>
> >> On Sep 13, 2013, at 4:54 PM, Tom Roeder <tmroeder at google.com> wrote:
> >>
> >> > Here is a pair of patches that fix and test
> >> > http://llvm.org/bugs/show_bug.cgi?id=14512. The fix applies to LLVM,
> >> > and I have currently put the test in the clang test suite. The test is
> >> > a minor tweak to the test proposed in the bug. Please take a look.
> >> >
> >> > The problem in this case is that the RecordStreamer implementation of
> >> > MCStreamer in the LTO module doesn't implement EmitCFIEndProcImpl, and
> >> > the default implementation in MCStreamer doesn't finish the frame.
> >> >
> >> > This patch touches the LTO code in tools/lto, but the test uses clang.
> >> > Is this the right way to do it? Is there a better location for LTO
> >> > tests?
> >> >
> >> Hi Tom,
> >>
> >> I haven't looked at the patch yet. However, the rule-of-thumb for where
> >> tests should go is that they should be in located where the code that tests
> >> them is. Clang doesn't have anything to do with LTO, so putting it in the
> >> clang test suite isn't really good. You'll want to generate a .ll file and
> >> place it in the LLVM part. That said, it's hard to know where such a test
> >> would go, since we don't really have many for LTO...But just pick a good
> >> place that's kind of related. :-)
> >>
> >> -bw
> >>
> >>
> >


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-- 
Peter