The following adds simplification of a scalar mode vec_select wrapping
a vec_concat. combine sees
(insn 7 4 8 2 (set (reg:V2DF 106)
(vec_concat:V2DF (plus:DF (vec_select:DF (reg/v:V2DF 101 [ p ])
(parallel [
(const_int 0 [0])
]))
(vec_select:DF (reg/v:V2DF 101 [ p ])
(parallel [
(const_int 1 [0x1])
])))
(plus:DF (vec_select:DF (reg/v:V2DF 101 [ p ])
(parallel [
(const_int 0 [0])
]))
(vec_select:DF (reg/v:V2DF 101 [ p ])
(parallel [
(const_int 1 [0x1])
]))))) "t.c":5:11 3234 {*sse3_haddv2df3}
(expr_list:REG_DEAD (reg/v:V2DF 101 [ p ])
(nil)))
(insn 8 7 9 2 (set (reg:DF 105)
(vec_select:DF (reg:V2DF 106)
(parallel [
(const_int 0 [0])
]))) "t.c":5:11 7297 {sse2_storelpd}
(expr_list:REG_DEAD (reg:V2DF 106)
(nil)))
and this should simplify and combine to
(set (reg:DF 105)
(plus:DF (vec_select:DF (reg:V2DF 109 [ p ])
(parallel [
(const_int 0 [0])
]))
(vec_select:DF (reg:V2DF 109 [ p ])
(parallel [
(const_int 1 [0x1])
]))))
which x86 can recognize (but rejects due to consting, see PR126328).
There'll be test coverage in gcc.target/i386/pr54400.c
Bootstrapped and tested on x86_64-unknown-linux-gnu.
OK?
Thanks,
Richard.
* simplify-rtx.cc (simplify_context::simplify_binary_operation_1):
Simplify scalar vec_select of vec_concat.
---
gcc/simplify-rtx.cc | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 882a11c5760..6f8ee53f209 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -5210,6 +5210,20 @@ simplify_ashift:
tmp_op, gen_rtx_PARALLEL (VOIDmode, vec));
return tmp;
}
+ /* If we select one half of a vec_concat, return that. */
+ else if (GET_CODE (trueop0) == VEC_CONCAT)
+ {
+ rtx subop0 = XEXP (trueop0, 0);
+ rtx subop1 = XEXP (trueop0, 1);
+ machine_mode mode0 = GET_MODE (subop0);
+ machine_mode mode1 = GET_MODE (subop1);
+ int i0 = INTVAL (XVECEXP (trueop1, 0, 0));
+ if (i0 == 0 && mode == mode0 && !side_effects_p (subop1))
+ return subop0;
+ if (known_eq (i0, GET_MODE_NUNITS (mode0))
+ && mode == mode1 && !side_effects_p (subop0))
+ return subop1;
+ }
}
else
{
--
2.51.0
