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Re: [06/77] Make GET_MODE_WIDER return an opt_mode
- From: Jeff Law <law at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org, richard dot sandiford at linaro dot org
- Date: Fri, 11 Aug 2017 12:05:36 -0600
- Subject: Re: [06/77] Make GET_MODE_WIDER return an opt_mode
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On 07/13/2017 02:40 AM, Richard Sandiford wrote:
> GET_MODE_WIDER previously returned VOIDmode if no wider mode existed.
> That would cause problems with stricter mode classes, since VOIDmode
> isn't for example a valid scalar integer or floating-point mode.
> This patch instead makes it return a new opt_mode<T> class, which
> holds either a T or nothing.
>
> 2017-07-13 Richard Sandiford <richard.sandiford@linaro.org>
> Alan Hayward <alan.hayward@arm.com>
> David Sherwood <david.sherwood@arm.com>
>
> gcc/
> * coretypes.h (opt_mode): New class.
> * machmode.h (opt_mode): Likewise.
> (opt_mode::else_void): New function.
> (opt_mode::operator *): Likewise.
> (opt_mode::exists): Likewise.
> (GET_MODE_WIDER_MODE): Turn into a function and return an opt_mode.
> (GET_MODE_2XWIDER_MODE): Likewise.
> (mode_iterator::get_wider): Update accordingly.
> (mode_iterator::get_2xwider): Likewise.
> (mode_iterator::get_known_wider): Likewise, turning into a template.
> * combine.c (make_extraction): Update use of GET_MODE_WIDER_MODE,
> forcing a wider mode to exist.
> * config/cr16/cr16.h (LONG_REG_P): Likewise.
> * rtlanal.c (init_num_sign_bit_copies_in_rep): Likewise.
> * config/c6x/c6x.c (c6x_rtx_costs): Update use of
> GET_MODE_2XWIDER_MODE, forcing a wider mode to exist.
> * lower-subreg.c (init_lower_subreg): Likewise.
> * optabs-libfuncs.c (init_sync_libfuncs_1): Likewise, but not
> on the final iteration.
> * config/i386/i386.c (ix86_expand_set_or_movmem): Check whether
> a wider mode exists before asking for a move pattern.
> (get_mode_wider_vector): Update use of GET_MODE_WIDER_MODE,
> forcing a wider mode to exist.
> (expand_vselect_vconcat): Update use of GET_MODE_2XWIDER_MODE,
> returning false if no such mode exists.
> * config/ia64/ia64.c (expand_vselect_vconcat): Likewise.
> * config/mips/mips.c (mips_expand_vselect_vconcat): Likewise.
> * expmed.c (init_expmed_one_mode): Update use of GET_MODE_WIDER_MODE.
> Avoid checking for a MODE_INT if we already know the mode is not a
> SCALAR_INT_MODE_P.
> (extract_high_half): Update use of GET_MODE_WIDER_MODE,
> forcing a wider mode to exist.
> (expmed_mult_highpart_optab): Likewise.
> (expmed_mult_highpart): Likewise.
> * expr.c (expand_expr_real_2): Update use of GET_MODE_WIDER_MODE,
> using else_void.
> * lto-streamer-in.c (lto_input_mode_table): Likewise.
> * optabs-query.c (find_widening_optab_handler_and_mode): Likewise.
> * stor-layout.c (bit_field_mode_iterator::next_mode): Likewise.
> * internal-fn.c (expand_mul_overflow): Update use of
> GET_MODE_2XWIDER_MODE.
> * omp-low.c (omp_clause_aligned_alignment): Likewise.
> * tree-ssa-math-opts.c (convert_mult_to_widen): Update use of
> GET_MODE_WIDER_MODE.
> (convert_plusminus_to_widen): Likewise.
> * tree-switch-conversion.c (array_value_type): Likewise.
> * var-tracking.c (emit_note_insn_var_location): Likewise.
> * tree-vrp.c (simplify_float_conversion_using_ranges): Likewise.
> Return false inside rather than outside the loop if no wider mode
> exists
> * optabs.c (expand_binop): Update use of GET_MODE_WIDER_MODE
> and GET_MODE_2XWIDER_MODE
> (can_compare_p): Use else_void.
> * gdbhooks.py (OptMachineModePrinter): New class.
> (build_pretty_printer): Use it for opt_mode.
>
> gcc/ada/
> * gcc-interface/decl.c (validate_size): Update use of
> GET_MODE_WIDER_MODE, forcing a wider mode to exist.
I'm not a big fan of the API here, particularly using operator* to
handle asserting the mode exists. I'd prefer to just use a member
function rather than overloading operator*.
What's the rationale behind using operator* to imply the assertion?
THe changes themsleves look fine, it's really just a question of the API
we present.
jeff