Generate a minimal llvm2ice.

Generate a minimal llvm2ice.

Generates minllvm2ice executable. Is same as llvm2ice, except that
it is the minimal implementation for processing PNaCl bitcode files.

Inclusion of code is dependent on compile flag BUILD_MIN_LLVM.

This code only effects the make file. Later CLs will ifdef
out code not to be included in minllvm2ice.

BUG=None

[Karl, 2014-10-10 21:49:38]

kschimpf@google.com changed reviewers:
+ jvoung@chromium.org, stichnot@chromium.org

[Jim Stichnoth, 2014-10-13 16:03:58]

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone
File Makefile.standalone (right):

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone#newcode108
Makefile.standalone:108: MIN_CXXFLAGS = -DBUILD_MIN_LLVM
LLVM?

Maybe something like SZ_MINIMAL?

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone#newcode113
Makefile.standalone:113: make_symlink: $(OBJDIR)/llvm2ice $(MINOBJDIR)/llvm2ice
I'm not thrilled about the build time doubling.  What do you think about
something like this?

- Set OBJDIR, OPTLEVEL, ASSERTIONS, etc. to something appropriate when MINIMAL
is defined.

- Change run-llvm2ice.py to be able to run FileCheck as part of its execution.

- Change the lit RUN lines accordingly.

- In run-llvm2ice.py, probe the llvm2ice binary and if it is a minimal build
that doesn't support requirements of the test (such as using IceConverter), just
return success without running llvm2ice+FileCheck.

[jvoung (off chromium), 2014-10-13 17:05:08]

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone
File Makefile.standalone (right):

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone#newcode108
Makefile.standalone:108: MIN_CXXFLAGS = -DBUILD_MIN_LLVM
On 2014/10/13 16:03:58, stichnot wrote:
> LLVM?
> 
> Maybe something like SZ_MINIMAL?

SHAVED_ICE

just kidding

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone#newcode113
Makefile.standalone:113: make_symlink: $(OBJDIR)/llvm2ice $(MINOBJDIR)/llvm2ice
On 2014/10/13 16:03:58, stichnot wrote:
> I'm not thrilled about the build time doubling.  What do you think about
> something like this?
> 
> - Set OBJDIR, OPTLEVEL, ASSERTIONS, etc. to something appropriate when MINIMAL
> is defined.
> 
> - Change run-llvm2ice.py to be able to run FileCheck as part of its execution.
> 
> - Change the lit RUN lines accordingly.
> 
> - In run-llvm2ice.py, probe the llvm2ice binary and if it is a minimal build
> that doesn't support requirements of the test (such as using IceConverter),
just
> return success without running llvm2ice+FileCheck.


If it helps, lit's llvm/utils/lit/lit/TestRunner.py has a "REQUIRES: ..."
keyword (besides "RUN" and "XFAIL"). E.g., "REQUIRES: asserts" and "REQUIRES:
fma3".

I'm not sure exactly how that works, but I think it checks a config file which
could be generated. I think it's similar to how they support per-arch
directories which require the particular backend to be configured-in and built.

[Karl, 2014-10-14 22:54:12]

Note: This CL has been replaced with

https://codereview.chromium.org/659513005

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone
File Makefile.standalone (right):

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone#newcode108
Makefile.standalone:108: MIN_CXXFLAGS = -DBUILD_MIN_LLVM
On 2014/10/13 16:03:58, stichnot wrote:
> LLVM?
> 
> Maybe something like SZ_MINIMAL?

Done.

https://codereview.chromium.org/644143002/diff/1/Makefile.standalone#newcode113
Makefile.standalone:113: make_symlink: $(OBJDIR)/llvm2ice $(MINOBJDIR)/llvm2ice
On 2014/10/13 16:03:58, stichnot wrote:
> I'm not thrilled about the build time doubling.  What do you think about
> something like this?
> 
> - Set OBJDIR, OPTLEVEL, ASSERTIONS, etc. to something appropriate when MINIMAL
> is defined.
> 
> - Change run-llvm2ice.py to be able to run FileCheck as part of its execution.
> 
> - Change the lit RUN lines accordingly.
> 
> - In run-llvm2ice.py, probe the llvm2ice binary and if it is a minimal build
> that doesn't support requirements of the test (such as using IceConverter),
just
> return success without running llvm2ice+FileCheck.

Made code dependent of command-line flag: "MINIMAL=t".

Also modified so that we now generate llvm2ice.build_atts holding the
corresponding build flags used to build llvm2ice. Added two concepts:

1) The REQUIRES lines to assert that defines when the lit test should be run.
and
2) A conditional %ifX command prefix to only run commands if the corresponding
built attributes are defined. In this case, the lit file  should contain tests
for multiple builds that use the same input. Tests that don't meet the build
conditions quietly succeed by doing nothing.