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Re: [patch, mips, tree] align microMIPS functions to 16 bits with -Os


On 05/28/2014 01:09 PM, Richard Sandiford wrote:
Sandra Loosemore <sandra@codesourcery.com> writes:

On 05/19/2014 01:38 PM, Sandra Loosemore wrote:

2014-05-19  Iain Sandoe  <iain@codesourcery.com>
          Catherine Moore  <clm@codesourcery.com>
          Sandra Loosemore  <sandra@codesourcery.com>

      gcc/
      * config/mips/mips.c (mips_set_current_function): Choose
      function alignment once the current mode is known.

      gcc/testsuite/
      * gcc.target/mips/umips-align-1.c: New.
      * gcc.target/mips/umips-align-2.c: New.
      * gcc.target/mips/umips-align-3.c: New.
      * gcc.target/mips/mips.exp: Add interlink-compressed to
      -mfoo/-mno-foo options.

Ping?

https://gcc.gnu.org/ml/gcc-patches/2014-05/msg01536.html

-Sandra

FAOD, I wasn't commenting because I still think it's the wrong place but
still don't have a specific counter-suggestion.  mips_set_current_function
is potentially called many times for the same function but setting the
alignment seems like something that should only happen once.  I think it
could potentially mean that alignment tests against the function address
could be optimised away based on the FUNCTION_BOUNDARY before
mips_set_current_function is called.

As a strawman, maybe adding a new target hook to cgraph_create_node
would work?

Hmmmm, why there?

Hopefully that'll prompt someone to say how stupid that
idea is and say what the right way of doing it would be.

If the implementation in the current patch is considered too stupid, I'd rather spend my time implementing a plausibly correct version on my next try instead of another stupid one.

My best guess is that this belongs somewhere in stor-layout.c, but the comments on layout_decl explicitly say FUNCTION_DECLs are not handled there, and I am not so familiar with the code as to be able to identify all the places where FUNCTION_DECLs ought to get their storage laid out but are not currently having it done. So that's probably a stupid idea, too.... :-(

-Sandra


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