[PATCH][committed] aarch64: Improve RTL representation of ADDP instructions

[Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>]

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Hi all,

Similar to the ADDLP instructions the non-widening ADDP ones can be
represented by adding the odd lanes with the even lanes of a vector.
These instructions take two vector inputs and the architecture spec
describes the operation as concatenating them together before going
through it with pairwise additions.
This patch chooses to represent ADDP on 64-bit and 128-bit input
vectors slightly differently, reasons explained in the comments
in aarhc64-simd.md.

Bootstrapped and tested on aarch64-none-linux-gnu and aarch64_be-none-elf.
Pushing to trunk.
Thanks,
Kyrill

gcc/ChangeLog:

	* config/aarch64/aarch64-simd.md (aarch64_addp<mode><vczle><vczbe>):
	Reimplement as...
	(aarch64_addp<mode>_insn): ... This...
	(aarch64_addp<mode><vczle><vczbe>_insn): ... And this.
	(aarch64_addp<mode>): New define_expand.

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diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index dbd6fc68914dc3c24c35034c37dc5cfe7e699ec2..b23067c6754e6e4c82f86dda27499bc7a4b676c3 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -7014,17 +7014,73 @@ (define_insn "aarch64_fac<optab><mode><vczle><vczbe>"
 
 ;; addp
 
-(define_insn "aarch64_addp<mode><vczle><vczbe>"
-  [(set (match_operand:VDQ_I 0 "register_operand" "=w")
-        (unspec:VDQ_I
-          [(match_operand:VDQ_I 1 "register_operand" "w")
-	   (match_operand:VDQ_I 2 "register_operand" "w")]
-          UNSPEC_ADDP))]
-  "TARGET_SIMD"
+;; ADDP with two registers semantically concatenates them and performs
+;; a pairwise addition on the result.  For 128-bit input modes represent this
+;; as a concatentation of the pairwise addition results of the two input
+;; registers.  This allow us to avoid using intermediate 256-bit modes.
+(define_insn "aarch64_addp<mode>_insn"
+  [(set (match_operand:VQ_I 0 "register_operand" "=w")
+	(vec_concat:VQ_I
+	  (plus:<VHALF>
+	    (vec_select:<VHALF>
+	      (match_operand:VQ_I 1 "register_operand" "w")
+	      (match_operand:VQ_I 3 "vect_par_cnst_even_or_odd_half"))
+	    (vec_select:<VHALF>
+	      (match_dup 1)
+	      (match_operand:VQ_I 4 "vect_par_cnst_even_or_odd_half")))
+	  (plus:<VHALF>
+	    (vec_select:<VHALF>
+	      (match_operand:VQ_I 2 "register_operand" "w")
+	      (match_dup 3))
+	    (vec_select:<VHALF>
+	      (match_dup 2)
+	      (match_dup 4)))))]
+  "TARGET_SIMD && !rtx_equal_p (operands[3], operands[4])"
+  "addp\t%<v>0<Vmtype>, %<v>1<Vmtype>, %<v>2<Vmtype>"
+  [(set_attr "type" "neon_reduc_add<q>")]
+)
+
+;; For 64-bit input modes an ADDP is represented as a concatentation
+;; of the input registers into an 128-bit register which is then fed
+;; into a pairwise add.  That way we avoid having to create intermediate
+;; 32-bit vector modes.
+(define_insn "aarch64_addp<mode><vczle><vczbe>_insn"
+  [(set (match_operand:VD_BHSI 0 "register_operand" "=w")
+	(plus:VD_BHSI
+	  (vec_select:VD_BHSI
+	    (vec_concat:<VDBL>
+	      (match_operand:VD_BHSI 1 "register_operand" "w")
+	      (match_operand:VD_BHSI 2 "register_operand" "w"))
+	    (match_operand:<VDBL> 3 "vect_par_cnst_even_or_odd_half"))
+	  (vec_select:VD_BHSI
+	    (vec_concat:<VDBL>
+	      (match_dup 1)
+	      (match_dup 2))
+	    (match_operand:<VDBL> 4 "vect_par_cnst_even_or_odd_half"))))]
+  "TARGET_SIMD && !rtx_equal_p (operands[3], operands[4])"
   "addp\t%<v>0<Vmtype>, %<v>1<Vmtype>, %<v>2<Vmtype>"
   [(set_attr "type" "neon_reduc_add<q>")]
 )
 
+(define_expand "aarch64_addp<mode>"
+  [(match_operand:VDQ_I 0 "register_operand")
+   (match_operand:VDQ_I 1 "register_operand")
+   (match_operand:VDQ_I 2 "register_operand")]
+  "TARGET_SIMD"
+  {
+    int nunits = GET_MODE_NUNITS (<MODE>mode).to_constant ();
+    if (known_eq (GET_MODE_BITSIZE (<MODE>mode), 128))
+      nunits /= 2;
+    rtx par_even = aarch64_gen_stepped_int_parallel (nunits, 0, 2);
+    rtx par_odd = aarch64_gen_stepped_int_parallel (nunits, 1, 2);
+    if (BYTES_BIG_ENDIAN)
+      std::swap (operands[1], operands[2]);
+    emit_insn (gen_aarch64_addp<mode>_insn (operands[0], operands[1],
+					    operands[2], par_even, par_odd));
+    DONE;
+  }
+)
+
 ;; sqrt
 
 (define_expand "sqrt<mode>2"