llvm dev - Feb 2014 - [LLVMdev] question about the alignment of the .text section

Is there a reason why the alignment of the .text section should be 4 when we are
optimizing for size (-Os or -Oz)? Note that when are optimizing for size, the
symbols inside .text section don't have any alignment constraints.
Alignment=4 for .text  with the unaligned symbols inside this section prevent
our linker from de-duplicating functions. Could the alignment of the .text
section be changed to 1? Could it cause any potential problems
(correctness/performance)?

clang -c -Os test.cpp -o test.o
readelf -S test.o
  [ 1] .text             PROGBITS         0000000000000000  00000040
       0000000000000052  0000000000000000  AX       0     0     4

Thanks!
Katya.


-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20140225/ab78d948/attachment.html>

On Tue, Feb 25, 2014 at 07:13:35PM +0000, Romanova, Katya
wrote:
> Is there a reason why the alignment of the .text section should be 4
> when we are optimizing for size (-Os or -Oz)?
Which target architecture?

Joerg

Joerg Sonnenberger <joerg <at> britannica.bec.de> writes:
> 
> On Tue, Feb 25, 2014 at 07:13:35PM +0000, Romanova, Katya wrote:
> > Is there a reason why the alignment of the .text section should be 4
> > when we are optimizing for size (-Os or -Oz)?
> 
> Which target architecture?
> 
> Joerg
Hi Joerg,

x86_64 Linux. I see 4 byte alignment for .text section when the compiler is
optimizing for size. 

Thanks!
Katya.