On 7/15/2021 4:08 AM, Jiufu Guo via Gcc-patches wrote:
Refine code for V2 according to review comments:
* Use if check instead assert, and refine assert
* Use better RE check for test case, e.g. (?n)/(?p)
* Use better wording for target.def
Currently, doloop.xx variable is using the type as niter which may be
shorter than word size. For some targets, it would be better to use
word size type. For example, on 64bit system, to access 32bit value,
subreg maybe used. Then using 64bit type maybe better for niter if
it can be present in both 32bit and 64bit.
This patch add target hook for querg perferred mode for doloop IV.
And update mode accordingly.
Bootstrap and regtest pass on powerpc64le, is this ok for trunk?
BR.
Jiufu
gcc/ChangeLog:
2021-07-15 Jiufu Guo <guoji...@linux.ibm.com>
PR target/61837
* config/rs6000/rs6000.c (TARGET_PREFERRED_DOLOOP_MODE): New hook.
(rs6000_preferred_doloop_mode): New hook.
* doc/tm.texi: Regenerate.
* doc/tm.texi.in: Add hook preferred_doloop_mode.
* target.def (preferred_doloop_mode): New hook.
* targhooks.c (default_preferred_doloop_mode): New hook.
* targhooks.h (default_preferred_doloop_mode): New hook.
* tree-ssa-loop-ivopts.c (compute_doloop_base_on_mode): New function.
(add_iv_candidate_for_doloop): Call targetm.preferred_doloop_mode
and compute_doloop_base_on_mode.
gcc/testsuite/ChangeLog:
2021-07-15 Jiufu Guo <guoji...@linux.ibm.com>
PR target/61837
* gcc.target/powerpc/pr61837.c: New test.
My first reaction was that whatever type corresponds to the target's
word_mode would be the right choice. But then I remembered things like
dbCC on m68k which had a more limited range. While I don't think m68k
uses the doloop bits, it's a clear example that the most desirable type
may not correspond to the word type for the target.
So my concern with this patch is its introducing more target
dependencies into the gimple pipeline which is generally considered
undesirable from a design standpoint. Is there any way to lower from
whatever type is chosen by ivopts to the target's desired type at the
gimple->rtl border rather than doing it in ivopts?
jeff
