diff options
| author | Richard Sandiford <richard.sandiford@linaro.org> | 2017-12-20 12:51:22 +0000 |
|---|---|---|
| committer | Richard Sandiford <rsandifo@gcc.gnu.org> | 2017-12-20 12:51:22 +0000 |
| commit | abd3c800109b95f09af3b3f1a7a43d9b7631f21c (patch) | |
| tree | 87a4afd30dc1d59b47bcd99fe6310f168476084b /gcc/dse.c | |
| parent | 27d229f709a928adc7c4e464509cc1633d127f3f (diff) | |
Add a gen_int_shift_amount helper function
This patch adds a helper routine that constructs rtxes
for constant shift amounts, given the mode of the value
being shifted. As well as helping with the SVE patches, this
is one step towards allowing CONST_INTs to have a real mode.
One long-standing problem has been to decide what the mode
of a shift count should be for arbitrary rtxes (as opposed to those
directly tied to a target pattern). Realistic choices would be
the mode of the shifted elements, word_mode, QImode, a 64-bit mode,
or the same mode as the shift optabs (in which case what should the
mode be when the target doesn't have a pattern?)
For now the patch picks a 64-bit mode, but with a ??? comment.
2017-12-20 Richard Sandiford <richard.sandiford@linaro.org>
Alan Hayward <alan.hayward@arm.com>
David Sherwood <david.sherwood@arm.com>
gcc/
* emit-rtl.h (gen_int_shift_amount): Declare.
* emit-rtl.c (gen_int_shift_amount): New function.
* asan.c (asan_emit_stack_protection): Use gen_int_shift_amount
instead of GEN_INT.
* calls.c (shift_return_value): Likewise.
* cse.c (fold_rtx): Likewise.
* dse.c (find_shift_sequence): Likewise.
* expmed.c (init_expmed_one_mode, store_bit_field_1, expand_shift_1)
(expand_shift, expand_smod_pow2): Likewise.
* lower-subreg.c (shift_cost): Likewise.
* optabs.c (expand_superword_shift, expand_doubleword_mult)
(expand_unop, expand_binop, shift_amt_for_vec_perm_mask)
(expand_vec_perm_var): Likewise.
* simplify-rtx.c (simplify_unary_operation_1): Likewise.
(simplify_binary_operation_1): Likewise.
* combine.c (try_combine, find_split_point, force_int_to_mode)
(simplify_shift_const_1, simplify_shift_const): Likewise.
(change_zero_ext): Likewise. Use simplify_gen_binary.
Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r255861
Diffstat (limited to 'gcc/dse.c')
| -rw-r--r-- | gcc/dse.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/gcc/dse.c b/gcc/dse.c index fbc6b25ac1e..c14eace483e 100644 --- a/gcc/dse.c +++ b/gcc/dse.c @@ -1642,8 +1642,9 @@ find_shift_sequence (int access_size, store_mode, byte); if (ret && CONSTANT_P (ret)) { + rtx shift_rtx = gen_int_shift_amount (new_mode, shift); ret = simplify_const_binary_operation (LSHIFTRT, new_mode, - ret, GEN_INT (shift)); + ret, shift_rtx); if (ret && CONSTANT_P (ret)) { byte = subreg_lowpart_offset (read_mode, new_mode); @@ -1679,7 +1680,8 @@ find_shift_sequence (int access_size, of one dsp where the cost of these two was not the same. But this really is a rare case anyway. */ target = expand_binop (new_mode, lshr_optab, new_reg, - GEN_INT (shift), new_reg, 1, OPTAB_DIRECT); + gen_int_shift_amount (new_mode, shift), + new_reg, 1, OPTAB_DIRECT); shift_seq = get_insns (); end_sequence (); |