On Thu, Dec 28, 2017 at 9:54 PM, Richard Sandiford
<richard.sandif...@linaro.org> wrote:
> This patch makes CONST_VECTOR_ELT handle implicitly-encoded elements,
> in a similar way to VECTOR_CST_ELT.
Ok.
Richard.
>
> 2017-12-28 Richard Sandiford <richard.sandif...@linaro.org>
>
> gcc/
> * rtl.h (CONST_VECTOR_ELT): Redefine to const_vector_elt.
> (const_vector_encoded_nelts): New function.
> (CONST_VECTOR_NUNITS): Redefine to use GET_MODE_NUNITS.
> (const_vector_int_elt, const_vector_elt): Declare.
> * emit-rtl.c (const_vector_int_elt_1): New function.
> (const_vector_elt): Likewise.
> * simplify-rtx.c (simplify_immed_subreg): Avoid taking the address
> of CONST_VECTOR_ELT.
>
> Index: gcc/rtl.h
> ===================================================================
> --- gcc/rtl.h 2017-12-22 13:12:00.662528577 +0000
> +++ gcc/rtl.h 2017-12-22 13:12:00.834520649 +0000
> @@ -1969,7 +1969,7 @@ #define CONST_FIXED_VALUE_LOW(r) \
> ((HOST_WIDE_INT) (CONST_FIXED_VALUE (r)->data.low))
>
> /* For a CONST_VECTOR, return element #n. */
> -#define CONST_VECTOR_ELT(RTX, N) XCVECEXP (RTX, 0, N, CONST_VECTOR)
> +#define CONST_VECTOR_ELT(RTX, N) const_vector_elt (RTX, N)
>
> #define CONST_VECTOR_NPATTERNS(RTX) \
> (RTL_FLAG_CHECK1 ("CONST_VECTOR_NPATTERNS", (RTX), CONST_VECTOR) \
> @@ -1987,8 +1987,16 @@ #define CONST_VECTOR_STEPPED_P(RTX) \
>
> #define CONST_VECTOR_ENCODED_ELT(RTX, N) XCVECEXP (RTX, 0, N, CONST_VECTOR)
>
> +/* Return the number of elements encoded directly in a CONST_VECTOR. */
> +
> +inline unsigned int
> +const_vector_encoded_nelts (const_rtx x)
> +{
> + return CONST_VECTOR_NPATTERNS (x) * CONST_VECTOR_NELTS_PER_PATTERN (x);
> +}
> +
> /* For a CONST_VECTOR, return the number of elements in a vector. */
> -#define CONST_VECTOR_NUNITS(RTX) XCVECLEN (RTX, 0, CONST_VECTOR)
> +#define CONST_VECTOR_NUNITS(RTX) GET_MODE_NUNITS (GET_MODE (RTX))
>
> /* For a SUBREG rtx, SUBREG_REG extracts the value we want a subreg of.
> SUBREG_BYTE extracts the byte-number. */
> @@ -3000,6 +3008,8 @@ unwrap_const_vec_duplicate (T x)
> }
>
> /* In emit-rtl.c. */
> +extern wide_int const_vector_int_elt (const_rtx, unsigned int);
> +extern rtx const_vector_elt (const_rtx, unsigned int);
> extern bool const_vec_series_p_1 (const_rtx, rtx *, rtx *);
>
> /* Return true if X is an integer constant vector that contains a linear
> Index: gcc/emit-rtl.c
> ===================================================================
> --- gcc/emit-rtl.c 2017-12-22 13:11:58.364634475 +0000
> +++ gcc/emit-rtl.c 2017-12-22 13:12:00.833520695 +0000
> @@ -5862,6 +5862,62 @@ init_emit (void)
> #endif
> }
>
> +/* Return the value of element I of CONST_VECTOR X as a wide_int. */
> +
> +wide_int
> +const_vector_int_elt (const_rtx x, unsigned int i)
> +{
> + /* First handle elements that are directly encoded. */
> + machine_mode elt_mode = GET_MODE_INNER (GET_MODE (x));
> + if (i < (unsigned int) XVECLEN (x, 0))
> + return rtx_mode_t (CONST_VECTOR_ENCODED_ELT (x, i), elt_mode);
> +
> + /* Identify the pattern that contains element I and work out the index of
> + the last encoded element for that pattern. */
> + unsigned int encoded_nelts = const_vector_encoded_nelts (x);
> + unsigned int npatterns = CONST_VECTOR_NPATTERNS (x);
> + unsigned int count = i / npatterns;
> + unsigned int pattern = i % npatterns;
> + unsigned int final_i = encoded_nelts - npatterns + pattern;
> +
> + /* If there are no steps, the final encoded value is the right one. */
> + if (!CONST_VECTOR_STEPPED_P (x))
> + return rtx_mode_t (CONST_VECTOR_ENCODED_ELT (x, final_i), elt_mode);
> +
> + /* Otherwise work out the value from the last two encoded elements. */
> + rtx v1 = CONST_VECTOR_ENCODED_ELT (x, final_i - npatterns);
> + rtx v2 = CONST_VECTOR_ENCODED_ELT (x, final_i);
> + wide_int diff = wi::sub (rtx_mode_t (v2, elt_mode),
> + rtx_mode_t (v1, elt_mode));
> + return wi::add (rtx_mode_t (v2, elt_mode), (count - 2) * diff);
> +}
> +
> +/* Return the value of element I of CONST_VECTOR X. */
> +
> +rtx
> +const_vector_elt (const_rtx x, unsigned int i)
> +{
> + /* First handle elements that are directly encoded. */
> + if (i < (unsigned int) XVECLEN (x, 0))
> + return CONST_VECTOR_ENCODED_ELT (x, i);
> +
> + /* If there are no steps, the final encoded value is the right one. */
> + if (!CONST_VECTOR_STEPPED_P (x))
> + {
> + /* Identify the pattern that contains element I and work out the index
> of
> + the last encoded element for that pattern. */
> + unsigned int encoded_nelts = const_vector_encoded_nelts (x);
> + unsigned int npatterns = CONST_VECTOR_NPATTERNS (x);
> + unsigned int pattern = i % npatterns;
> + unsigned int final_i = encoded_nelts - npatterns + pattern;
> + return CONST_VECTOR_ENCODED_ELT (x, final_i);
> + }
> +
> + /* Otherwise work out the value from the last two encoded elements. */
> + return immed_wide_int_const (const_vector_int_elt (x, i),
> + GET_MODE_INNER (GET_MODE (x)));
> +}
> +
> /* Return true if X is a valid element for a CONST_VECTOR of the given
> mode. */
>
> Index: gcc/simplify-rtx.c
> ===================================================================
> --- gcc/simplify-rtx.c 2017-12-22 13:12:00.662528577 +0000
> +++ gcc/simplify-rtx.c 2017-12-22 13:12:00.834520649 +0000
> @@ -5990,13 +5990,11 @@ simplify_immed_subreg (fixed_size_mode o
> if (GET_CODE (op) == CONST_VECTOR)
> {
> num_elem = CONST_VECTOR_NUNITS (op);
> - elems = &CONST_VECTOR_ELT (op, 0);
> elem_bitsize = GET_MODE_UNIT_BITSIZE (innermode);
> }
> else
> {
> num_elem = 1;
> - elems = &op;
> elem_bitsize = max_bitsize;
> }
> /* If this asserts, it is too complicated; reducing value_bit may help. */
> @@ -6007,7 +6005,9 @@ simplify_immed_subreg (fixed_size_mode o
> for (elem = 0; elem < num_elem; elem++)
> {
> unsigned char * vp;
> - rtx el = elems[elem];
> + rtx el = (GET_CODE (op) == CONST_VECTOR
> + ? CONST_VECTOR_ELT (op, elem)
> + : op);
>
> /* Vectors are kept in target memory order. (This is probably
> a mistake.) */
