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authorRichard Sandiford <richard.sandiford@linaro.org>2017-12-16 14:14:18 +0000
committerRichard Sandiford <rsandifo@gcc.gnu.org>2017-12-16 14:14:18 +0000
commit7e594332e400b26cd2df4a40980d08ffc7fcfc1a (patch)
tree7aeb539f672b7290a347caab3491519b27867ab0 /gcc/dse.c
parent05210ba63707fd3dc120f0f5a76add5ca172881e (diff)
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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, 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 the mode of the shifted elements, but with a ??? comment. 2017-11-06 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: r255745
Diffstat (limited to 'gcc/dse.c')
-rw-r--r--gcc/dse.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/gcc/dse.c b/gcc/dse.c
index fbc6b25..c14eace 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 ();