llvm dev - Dec 2015 - Any way to disable the alignment of functions?

Hi,

I am trying to test if disabling function (entry) alignment has any effect on
performance. On my x86 machine, all functions seem to get aligned to 16-bytes.
I know that GCC provides a flag (-fno-align-functions) to disable function
alignment. However, I could not find the similar flag for clang.
According to the following quote from LLVM doc, clang delegates the job to the
target in case no attributes are specified for a function.

"An explicit alignment may be specified for a function. If not present, or
if the alignment is set to zero, the alignment of the function is set by the
target to whatever it feels convenient.”

So, as a first try, I dived into the “EmitAlignment” code in AsmPrinter.cpp and
simply removed the function alignment part. Interestingly the compilation seems
flawless at many cases (large programs) but on a few programs, it produces a
segfault-generating executable. So my guess is that for some functions,
alignment is necessary for soundness, not just performance.

regards