On Mon, Oct 23, 2017 at 1:22 PM, Richard Sandiford
<richard.sandif...@linaro.org> wrote:
> This patch adds a fixed_size_mode machine_mode wrapper
> for modes that are known to have a fixed size. That applies
> to all current modes, but future patches will add support for
> variable-sized modes.
>
> The use of this class should be pretty restricted. One important
> use case is to hold the mode of static data, which can never be
> variable-sized with current file formats. Another is to hold
> the modes of registers involved in __builtin_apply and
> __builtin_result, since those interfaces don't cope well with
> variable-sized data.
>
> The class can also be useful when reinterpreting the contents of
> a fixed-length bit string as a different kind of value.
Ok.
Richard.
>
> 2017-10-23 Richard Sandiford <richard.sandif...@linaro.org>
> Alan Hayward <alan.hayw...@arm.com>
> David Sherwood <david.sherw...@arm.com>
>
> gcc/
> * machmode.h (fixed_size_mode): New class.
> * rtl.h (get_pool_mode): Return fixed_size_mode.
> * gengtype.c (main): Add fixed_size_mode.
> * target.def (get_raw_result_mode): Return a fixed_size_mode.
> (get_raw_arg_mode): Likewise.
> * doc/tm.texi: Regenerate.
> * targhooks.h (default_get_reg_raw_mode): Return a fixed_size_mode.
> * targhooks.c (default_get_reg_raw_mode): Likewise.
> * config/ia64/ia64.c (ia64_get_reg_raw_mode): Likewise.
> * config/mips/mips.c (mips_get_reg_raw_mode): Likewise.
> * config/msp430/msp430.c (msp430_get_raw_arg_mode): Likewise.
> (msp430_get_raw_result_mode): Likewise.
> * config/avr/avr-protos.h (regmask): Use as_a <fixed_side_mode>
> * dbxout.c (dbxout_parms): Require fixed-size modes.
> * expr.c (copy_blkmode_from_reg, copy_blkmode_to_reg): Likewise.
> * gimple-ssa-store-merging.c (encode_tree_to_bitpos): Likewise.
> * omp-low.c (lower_oacc_reductions): Likewise.
> * simplify-rtx.c (simplify_immed_subreg): Take fixed_size_modes.
> (simplify_subreg): Update accordingly.
> * varasm.c (constant_descriptor_rtx::mode): Change to fixed_size_mode.
> (force_const_mem): Update accordingly. Return NULL_RTX for modes
> that aren't fixed-size.
> (get_pool_mode): Return a fixed_size_mode.
> (output_constant_pool_2): Take a fixed_size_mode.
>
> Index: gcc/machmode.h
> ===================================================================
> --- gcc/machmode.h 2017-09-15 14:47:33.184331588 +0100
> +++ gcc/machmode.h 2017-10-23 11:42:52.014721093 +0100
> @@ -652,6 +652,39 @@ GET_MODE_2XWIDER_MODE (const T &m)
> extern const unsigned char mode_complex[NUM_MACHINE_MODES];
> #define GET_MODE_COMPLEX_MODE(MODE) ((machine_mode) mode_complex[MODE])
>
> +/* Represents a machine mode that must have a fixed size. The main
> + use of this class is to represent the modes of objects that always
> + have static storage duration, such as constant pool entries.
> + (No current target supports the concept of variable-size static data.) */
> +class fixed_size_mode
> +{
> +public:
> + typedef mode_traits<fixed_size_mode>::from_int from_int;
> +
> + ALWAYS_INLINE fixed_size_mode () {}
> + ALWAYS_INLINE fixed_size_mode (from_int m) : m_mode (machine_mode (m)) {}
> + ALWAYS_INLINE fixed_size_mode (const scalar_mode &m) : m_mode (m) {}
> + ALWAYS_INLINE fixed_size_mode (const scalar_int_mode &m) : m_mode (m) {}
> + ALWAYS_INLINE fixed_size_mode (const scalar_float_mode &m) : m_mode (m) {}
> + ALWAYS_INLINE fixed_size_mode (const scalar_mode_pod &m) : m_mode (m) {}
> + ALWAYS_INLINE fixed_size_mode (const scalar_int_mode_pod &m) : m_mode (m)
> {}
> + ALWAYS_INLINE fixed_size_mode (const complex_mode &m) : m_mode (m) {}
> + ALWAYS_INLINE operator machine_mode () const { return m_mode; }
> +
> + static bool includes_p (machine_mode);
> +
> +protected:
> + machine_mode m_mode;
> +};
> +
> +/* Return true if MODE has a fixed size. */
> +
> +inline bool
> +fixed_size_mode::includes_p (machine_mode)
> +{
> + return true;
> +}
> +
> extern opt_machine_mode mode_for_size (unsigned int, enum mode_class, int);
>
> /* Return the machine mode to use for a MODE_INT of SIZE bits, if one
> Index: gcc/rtl.h
> ===================================================================
> --- gcc/rtl.h 2017-10-23 11:42:47.297720974 +0100
> +++ gcc/rtl.h 2017-10-23 11:42:52.015721094 +0100
> @@ -3020,7 +3020,7 @@ extern rtx force_const_mem (machine_mode
> struct function;
> extern rtx get_pool_constant (const_rtx);
> extern rtx get_pool_constant_mark (rtx, bool *);
> -extern machine_mode get_pool_mode (const_rtx);
> +extern fixed_size_mode get_pool_mode (const_rtx);
> extern rtx simplify_subtraction (rtx);
> extern void decide_function_section (tree);
>
> Index: gcc/gengtype.c
> ===================================================================
> --- gcc/gengtype.c 2017-05-23 19:29:56.919436344 +0100
> +++ gcc/gengtype.c 2017-10-23 11:42:52.014721093 +0100
> @@ -5197,6 +5197,7 @@ #define POS_HERE(Call) do { pos.file = t
> POS_HERE (do_scalar_typedef ("JCF_u2", &pos));
> POS_HERE (do_scalar_typedef ("void", &pos));
> POS_HERE (do_scalar_typedef ("machine_mode", &pos));
> + POS_HERE (do_scalar_typedef ("fixed_size_mode", &pos));
> POS_HERE (do_typedef ("PTR",
> create_pointer (resolve_typedef ("void", &pos)),
> &pos));
> Index: gcc/target.def
> ===================================================================
> --- gcc/target.def 2017-10-23 11:41:23.134456913 +0100
> +++ gcc/target.def 2017-10-23 11:42:52.017721094 +0100
> @@ -5021,7 +5021,7 @@ DEFHOOK
> "This target hook returns the mode to be used when accessing raw return\
> registers in @code{__builtin_return}. Define this macro if the value\
> in @var{reg_raw_mode} is not correct.",
> - machine_mode, (int regno),
> + fixed_size_mode, (int regno),
> default_get_reg_raw_mode)
>
> /* Return a mode wide enough to copy any argument value that might be
> @@ -5031,7 +5031,7 @@ DEFHOOK
> "This target hook returns the mode to be used when accessing raw argument\
> registers in @code{__builtin_apply_args}. Define this macro if the value\
> in @var{reg_raw_mode} is not correct.",
> - machine_mode, (int regno),
> + fixed_size_mode, (int regno),
> default_get_reg_raw_mode)
>
> HOOK_VECTOR_END (calls)
> Index: gcc/doc/tm.texi
> ===================================================================
> --- gcc/doc/tm.texi 2017-10-23 11:41:22.175925023 +0100
> +++ gcc/doc/tm.texi 2017-10-23 11:42:52.012721093 +0100
> @@ -4536,11 +4536,11 @@ This macro has effect in @option{-fpcc-s
> nothing when you use @option{-freg-struct-return} mode.
> @end defmac
>
> -@deftypefn {Target Hook} machine_mode TARGET_GET_RAW_RESULT_MODE (int
> @var{regno})
> +@deftypefn {Target Hook} fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int
> @var{regno})
> This target hook returns the mode to be used when accessing raw return
> registers in @code{__builtin_return}. Define this macro if the value in
> @var{reg_raw_mode} is not correct.
> @end deftypefn
>
> -@deftypefn {Target Hook} machine_mode TARGET_GET_RAW_ARG_MODE (int
> @var{regno})
> +@deftypefn {Target Hook} fixed_size_mode TARGET_GET_RAW_ARG_MODE (int
> @var{regno})
> This target hook returns the mode to be used when accessing raw argument
> registers in @code{__builtin_apply_args}. Define this macro if the value in
> @var{reg_raw_mode} is not correct.
> @end deftypefn
>
> Index: gcc/targhooks.h
> ===================================================================
> --- gcc/targhooks.h 2017-10-02 09:08:43.318933786 +0100
> +++ gcc/targhooks.h 2017-10-23 11:42:52.017721094 +0100
> @@ -233,7 +233,7 @@ extern int default_jump_align_max_skip (
> extern section * default_function_section(tree decl, enum node_frequency
> freq,
> bool startup, bool exit);
> extern machine_mode default_dwarf_frame_reg_mode (int);
> -extern machine_mode default_get_reg_raw_mode (int);
> +extern fixed_size_mode default_get_reg_raw_mode (int);
> extern bool default_keep_leaf_when_profiled ();
>
> extern void *default_get_pch_validity (size_t *);
> Index: gcc/targhooks.c
> ===================================================================
> --- gcc/targhooks.c 2017-10-23 11:41:23.195392846 +0100
> +++ gcc/targhooks.c 2017-10-23 11:42:52.017721094 +0100
> @@ -1834,10 +1834,12 @@ default_dwarf_frame_reg_mode (int regno)
> /* To be used by targets where reg_raw_mode doesn't return the right
> mode for registers used in apply_builtin_return and apply_builtin_arg. */
>
> -machine_mode
> +fixed_size_mode
> default_get_reg_raw_mode (int regno)
> {
> - return reg_raw_mode[regno];
> + /* Targets must override this hook if the underlying register is
> + variable-sized. */
> + return as_a <fixed_size_mode> (reg_raw_mode[regno]);
> }
>
> /* Return true if a leaf function should stay leaf even with profiling
> Index: gcc/config/ia64/ia64.c
> ===================================================================
> --- gcc/config/ia64/ia64.c 2017-10-23 11:41:32.363050263 +0100
> +++ gcc/config/ia64/ia64.c 2017-10-23 11:42:52.009721093 +0100
> @@ -329,7 +329,7 @@ static tree ia64_fold_builtin (tree, int
> static tree ia64_builtin_decl (unsigned, bool);
>
> static reg_class_t ia64_preferred_reload_class (rtx, reg_class_t);
> -static machine_mode ia64_get_reg_raw_mode (int regno);
> +static fixed_size_mode ia64_get_reg_raw_mode (int regno);
> static section * ia64_hpux_function_section (tree, enum node_frequency,
> bool, bool);
>
> @@ -11328,7 +11328,7 @@ ia64_dconst_0_375 (void)
> return ia64_dconst_0_375_rtx;
> }
>
> -static machine_mode
> +static fixed_size_mode
> ia64_get_reg_raw_mode (int regno)
> {
> if (FR_REGNO_P (regno))
> Index: gcc/config/mips/mips.c
> ===================================================================
> --- gcc/config/mips/mips.c 2017-10-23 11:41:32.365050264 +0100
> +++ gcc/config/mips/mips.c 2017-10-23 11:42:52.010721093 +0100
> @@ -1132,7 +1132,6 @@ static rtx mips_find_pic_call_symbol (rt
> static int mips_register_move_cost (machine_mode, reg_class_t,
> reg_class_t);
> static unsigned int mips_function_arg_boundary (machine_mode, const_tree);
> -static machine_mode mips_get_reg_raw_mode (int regno);
> static rtx mips_gen_const_int_vector_shuffle (machine_mode, int);
>
> /* This hash table keeps track of implicit "mips16" and "nomips16" attributes
> @@ -6111,7 +6110,7 @@ mips_function_arg_boundary (machine_mode
>
> /* Implement TARGET_GET_RAW_RESULT_MODE and TARGET_GET_RAW_ARG_MODE. */
>
> -static machine_mode
> +static fixed_size_mode
> mips_get_reg_raw_mode (int regno)
> {
> if (TARGET_FLOATXX && FP_REG_P (regno))
> Index: gcc/config/msp430/msp430.c
> ===================================================================
> --- gcc/config/msp430/msp430.c 2017-10-23 11:41:23.047405581 +0100
> +++ gcc/config/msp430/msp430.c 2017-10-23 11:42:52.011721093 +0100
> @@ -1398,16 +1398,17 @@ msp430_return_in_memory (const_tree ret_
> #undef TARGET_GET_RAW_ARG_MODE
> #define TARGET_GET_RAW_ARG_MODE msp430_get_raw_arg_mode
>
> -static machine_mode
> +static fixed_size_mode
> msp430_get_raw_arg_mode (int regno)
> {
> - return (regno == ARG_POINTER_REGNUM) ? VOIDmode : Pmode;
> + return as_a <fixed_size_mode> (regno == ARG_POINTER_REGNUM
> + ? VOIDmode : Pmode);
> }
>
> #undef TARGET_GET_RAW_RESULT_MODE
> #define TARGET_GET_RAW_RESULT_MODE msp430_get_raw_result_mode
>
> -static machine_mode
> +static fixed_size_mode
> msp430_get_raw_result_mode (int regno ATTRIBUTE_UNUSED)
> {
> return Pmode;
> Index: gcc/config/avr/avr-protos.h
> ===================================================================
> --- gcc/config/avr/avr-protos.h 2017-10-23 11:41:22.812366984 +0100
> +++ gcc/config/avr/avr-protos.h 2017-10-23 11:42:52.007721093 +0100
> @@ -132,7 +132,7 @@ extern bool avr_casei_sequence_check_ope
> static inline unsigned
> regmask (machine_mode mode, unsigned regno)
> {
> - return ((1u << GET_MODE_SIZE (mode)) - 1) << regno;
> + return ((1u << GET_MODE_SIZE (as_a <fixed_size_mode> (mode))) - 1) <<
> regno;
> }
>
> extern void avr_fix_inputs (rtx*, unsigned, unsigned);
> Index: gcc/dbxout.c
> ===================================================================
> --- gcc/dbxout.c 2017-10-10 17:55:22.088175460 +0100
> +++ gcc/dbxout.c 2017-10-23 11:42:52.011721093 +0100
> @@ -3393,12 +3393,16 @@ dbxout_parms (tree parms)
> {
> ++debug_nesting;
> emit_pending_bincls_if_required ();
> + fixed_size_mode rtl_mode, type_mode;
>
> for (; parms; parms = DECL_CHAIN (parms))
> if (DECL_NAME (parms)
> && TREE_TYPE (parms) != error_mark_node
> && DECL_RTL_SET_P (parms)
> - && DECL_INCOMING_RTL (parms))
> + && DECL_INCOMING_RTL (parms)
> + /* We can't represent variable-sized types in this format. */
> + && is_a <fixed_size_mode> (TYPE_MODE (TREE_TYPE (parms)), &type_mode)
> + && is_a <fixed_size_mode> (GET_MODE (DECL_RTL (parms)), &rtl_mode))
> {
> tree eff_type;
> char letter;
> @@ -3555,10 +3559,9 @@ dbxout_parms (tree parms)
> /* Make a big endian correction if the mode of the type of the
> parameter is not the same as the mode of the rtl. */
> if (BYTES_BIG_ENDIAN
> - && TYPE_MODE (TREE_TYPE (parms)) != GET_MODE (DECL_RTL
> (parms))
> - && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (parms))) <
> UNITS_PER_WORD)
> - number += (GET_MODE_SIZE (GET_MODE (DECL_RTL (parms)))
> - - GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (parms))));
> + && type_mode != rtl_mode
> + && GET_MODE_SIZE (type_mode) < UNITS_PER_WORD)
> + number += GET_MODE_SIZE (rtl_mode) - GET_MODE_SIZE (type_mode);
> }
> else
> /* ??? We don't know how to represent this argument. */
> Index: gcc/expr.c
> ===================================================================
> --- gcc/expr.c 2017-10-23 11:42:34.915720660 +0100
> +++ gcc/expr.c 2017-10-23 11:42:52.013721093 +0100
> @@ -2628,9 +2628,10 @@ copy_blkmode_from_reg (rtx target, rtx s
> rtx src = NULL, dst = NULL;
> unsigned HOST_WIDE_INT bitsize = MIN (TYPE_ALIGN (type), BITS_PER_WORD);
> unsigned HOST_WIDE_INT bitpos, xbitpos, padding_correction = 0;
> - machine_mode mode = GET_MODE (srcreg);
> - machine_mode tmode = GET_MODE (target);
> - machine_mode copy_mode;
> + /* No current ABI uses variable-sized modes to pass a BLKmnode type. */
> + fixed_size_mode mode = as_a <fixed_size_mode> (GET_MODE (srcreg));
> + fixed_size_mode tmode = as_a <fixed_size_mode> (GET_MODE (target));
> + fixed_size_mode copy_mode;
>
> /* BLKmode registers created in the back-end shouldn't have survived. */
> gcc_assert (mode != BLKmode);
> @@ -2728,19 +2729,21 @@ copy_blkmode_from_reg (rtx target, rtx s
> }
> }
>
> -/* Copy BLKmode value SRC into a register of mode MODE. Return the
> +/* Copy BLKmode value SRC into a register of mode MODE_IN. Return the
> register if it contains any data, otherwise return null.
>
> This is used on targets that return BLKmode values in registers. */
>
> rtx
> -copy_blkmode_to_reg (machine_mode mode, tree src)
> +copy_blkmode_to_reg (machine_mode mode_in, tree src)
> {
> int i, n_regs;
> unsigned HOST_WIDE_INT bitpos, xbitpos, padding_correction = 0, bytes;
> unsigned int bitsize;
> rtx *dst_words, dst, x, src_word = NULL_RTX, dst_word = NULL_RTX;
> - machine_mode dst_mode;
> + /* No current ABI uses variable-sized modes to pass a BLKmnode type. */
> + fixed_size_mode mode = as_a <fixed_size_mode> (mode_in);
> + fixed_size_mode dst_mode;
>
> gcc_assert (TYPE_MODE (TREE_TYPE (src)) == BLKmode);
>
> Index: gcc/gimple-ssa-store-merging.c
> ===================================================================
> --- gcc/gimple-ssa-store-merging.c 2017-10-09 11:50:52.446411111 +0100
> +++ gcc/gimple-ssa-store-merging.c 2017-10-23 11:42:52.014721093 +0100
> @@ -401,8 +401,11 @@ encode_tree_to_bitpos (tree expr, unsign
> The awkwardness comes from the fact that bitpos is counted from the
> most significant bit of a byte. */
>
> + /* We must be dealing with fixed-size data at this point, since the
> + total size is also fixed. */
> + fixed_size_mode mode = as_a <fixed_size_mode> (TYPE_MODE (TREE_TYPE
> (expr)));
> /* Allocate an extra byte so that we have space to shift into. */
> - unsigned int byte_size = GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))) + 1;
> + unsigned int byte_size = GET_MODE_SIZE (mode) + 1;
> unsigned char *tmpbuf = XALLOCAVEC (unsigned char, byte_size);
> memset (tmpbuf, '\0', byte_size);
> /* The store detection code should only have allowed constants that are
> Index: gcc/omp-low.c
> ===================================================================
> --- gcc/omp-low.c 2017-10-10 17:55:22.100175459 +0100
> +++ gcc/omp-low.c 2017-10-23 11:42:52.015721094 +0100
> @@ -5067,8 +5067,10 @@ lower_oacc_reductions (location_t loc, t
> v1 = v2 = v3 = var;
>
> /* Determine position in reduction buffer, which may be used
> - by target. */
> - machine_mode mode = TYPE_MODE (TREE_TYPE (var));
> + by target. The parser has ensured that this is not a
> + variable-sized type. */
> + fixed_size_mode mode
> + = as_a <fixed_size_mode> (TYPE_MODE (TREE_TYPE (var)));
> unsigned align = GET_MODE_ALIGNMENT (mode) / BITS_PER_UNIT;
> offset = (offset + align - 1) & ~(align - 1);
> tree off = build_int_cst (sizetype, offset);
> Index: gcc/simplify-rtx.c
> ===================================================================
> --- gcc/simplify-rtx.c 2017-10-23 11:41:41.550050496 +0100
> +++ gcc/simplify-rtx.c 2017-10-23 11:42:52.016721094 +0100
> @@ -48,8 +48,6 @@ #define HWI_SIGN_EXTEND(low) \
> static rtx neg_const_int (machine_mode, const_rtx);
> static bool plus_minus_operand_p (const_rtx);
> static rtx simplify_plus_minus (enum rtx_code, machine_mode, rtx, rtx);
> -static rtx simplify_immed_subreg (machine_mode, rtx, machine_mode,
> - unsigned int);
> static rtx simplify_associative_operation (enum rtx_code, machine_mode,
> rtx, rtx);
> static rtx simplify_relational_operation_1 (enum rtx_code, machine_mode,
> @@ -5802,8 +5800,8 @@ simplify_ternary_operation (enum rtx_cod
> and then repacking them again for OUTERMODE. */
>
> static rtx
> -simplify_immed_subreg (machine_mode outermode, rtx op,
> - machine_mode innermode, unsigned int byte)
> +simplify_immed_subreg (fixed_size_mode outermode, rtx op,
> + fixed_size_mode innermode, unsigned int byte)
> {
> enum {
> value_bit = 8,
> @@ -6171,7 +6169,18 @@ simplify_subreg (machine_mode outermode,
> || CONST_DOUBLE_AS_FLOAT_P (op)
> || GET_CODE (op) == CONST_FIXED
> || GET_CODE (op) == CONST_VECTOR)
> - return simplify_immed_subreg (outermode, op, innermode, byte);
> + {
> + /* simplify_immed_subreg deconstructs OP into bytes and constructs
> + the result from bytes, so it only works if the sizes of the modes
> + are known at compile time. Cases that apply to general modes
> + should be handled here before calling simplify_immed_subreg. */
> + fixed_size_mode fs_outermode, fs_innermode;
> + if (is_a <fixed_size_mode> (outermode, &fs_outermode)
> + && is_a <fixed_size_mode> (innermode, &fs_innermode))
> + return simplify_immed_subreg (fs_outermode, op, fs_innermode, byte);
> +
> + return NULL_RTX;
> + }
>
> /* Changing mode twice with SUBREG => just change it once,
> or not at all if changing back op starting mode. */
> Index: gcc/varasm.c
> ===================================================================
> --- gcc/varasm.c 2017-10-23 11:42:34.927720660 +0100
> +++ gcc/varasm.c 2017-10-23 11:42:52.018721094 +0100
> @@ -3584,7 +3584,7 @@ struct GTY((chain_next ("%h.next"), for_
> rtx constant;
> HOST_WIDE_INT offset;
> hashval_t hash;
> - machine_mode mode;
> + fixed_size_mode mode;
> unsigned int align;
> int labelno;
> int mark;
> @@ -3760,10 +3760,11 @@ simplify_subtraction (rtx x)
> }
>
> /* Given a constant rtx X, make (or find) a memory constant for its value
> - and return a MEM rtx to refer to it in memory. */
> + and return a MEM rtx to refer to it in memory. IN_MODE is the mode
> + of X. */
>
> rtx
> -force_const_mem (machine_mode mode, rtx x)
> +force_const_mem (machine_mode in_mode, rtx x)
> {
> struct constant_descriptor_rtx *desc, tmp;
> struct rtx_constant_pool *pool;
> @@ -3772,6 +3773,11 @@ force_const_mem (machine_mode mode, rtx
> hashval_t hash;
> unsigned int align;
> constant_descriptor_rtx **slot;
> + fixed_size_mode mode;
> +
> + /* We can't force variable-sized objects to memory. */
> + if (!is_a <fixed_size_mode> (in_mode, &mode))
> + return NULL_RTX;
>
> /* If we're not allowed to drop X into the constant pool, don't. */
> if (targetm.cannot_force_const_mem (mode, x))
> @@ -3881,7 +3887,7 @@ get_pool_constant_mark (rtx addr, bool *
>
> /* Similar, return the mode. */
>
> -machine_mode
> +fixed_size_mode
> get_pool_mode (const_rtx addr)
> {
> return SYMBOL_REF_CONSTANT (addr)->mode;
> @@ -3901,7 +3907,7 @@ constant_pool_empty_p (void)
> in MODE with known alignment ALIGN. */
>
> static void
> -output_constant_pool_2 (machine_mode mode, rtx x, unsigned int align)
> +output_constant_pool_2 (fixed_size_mode mode, rtx x, unsigned int align)
> {
> switch (GET_MODE_CLASS (mode))
> {
