[PATCH 4/5] Generalise invalid_mode_change_p
Mon Sep 22 16:29:00 GMT 2014
On 09/22/14 01:34, Richard Sandiford wrote:
> Jeff Law <email@example.com> writes:
>> On 09/18/14 04:25, Richard Sandiford wrote:
>>> This is the main patch for the bug. We should treat a register as invalid
>>> for a mode change if simplify_subreg_regno cannot provide a new register
>>> number for the result. We should treat a class as invalid for a mode change
>>> if all registers in the class are invalid. This is an extension of the old
>>> CANNOT_CHANGE_MODE_CLASS-based check (simplify_subreg_regno checks C_C_C_M).
>>> I forgot to say that the patch is a prerequisite to removing aarch64's
>>> C_C_C_M. There are other prerequisites too, but removing C_C_C_M without
>>> this patch caused regressions in the existing testsuite, which is why no
>>> new tests are needed.
>>> * hard-reg-set.h: Include hash-table.h.
>>> (target_hard_regs): Add a finalize method and a x_simplifiable_subregs
>>> * target-globals.c (target_globals::~target_globals): Handle
>>> * rtl.h (subreg_shape): New structure.
>>> (shape_of_subreg): New function.
>>> (simplifiable_subregs): Declare.
>>> * reginfo.c (simplifiable_subreg): New structure.
>>> (simplifiable_subregs_hasher): Likewise.
>>> (simplifiable_subregs): New function.
>>> (invalid_mode_changes): Delete.
>>> (alid_mode_changes, valid_mode_changes_obstack): New variables.
>>> (record_subregs_of_mode): Remove subregs_of_mode parameter.
>>> Record valid mode changes in valid_mode_changes.
>>> (find_subregs_of_mode): Remove subregs_of_mode parameter.
>>> Update calls to record_subregs_of_mode.
>>> (init_subregs_of_mode): Remove invalid_mode_changes and bitmap
>>> handling. Initialize new variables. Update call to
>>> (invalid_mode_change_p): Check new variables instead of
>>> (finish_subregs_of_mode): Finalize new variables instead of
>>> (target_hard_regs::finalize): New function.
>>> * ira-costs.c (print_allocno_costs): Call invalid_mode_change_p
>>> even when CLASS_CANNOT_CHANGE_MODE is undefined.
>>> Index: gcc/rtl.h
>>> --- gcc/rtl.h 2014-09-15 11:55:40.459855161 +0100
>>> +++ gcc/rtl.h 2014-09-15 12:26:21.249077760 +0100
>>> +/* Return the shape of a SUBREG rtx. */
>>> +static inline subreg_shape
>>> +shape_of_subreg (const_rtx x)
>>> + return subreg_shape (GET_MODE (SUBREG_REG (x)),
>>> + SUBREG_BYTE (x), GET_MODE (x));
>> Is there some reason you don't have a constructor that accepts a
> I was worried that by allowing implicit const_rtx->subreg_shape
> conversions, it would be less obvious that the rtx has to have
> code SUBREG. I.e. a checked conversion would be hidden in the
> constructor rather than being explicit.
> If with David's new rtx hierarchy we end up with an rtx_subreg
> subclass then I agree we should have a constructor that takes
> one of those.
I'm not sure if I was explicit, but the patch is fine, that was more a
curiosity on my part than anything.
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