[PATCH][committed] aarch64: Add pattern to match zero-extending scalar result of ADDLV

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

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Hi all,

The vaddlv_u8 and vaddlv_u16 intrinsics produce a widened scalar result (uint16_t and uint32_t).
The ADDLV instructions themselves zero the rest of the V register, which gives us a free zero-extension
to 32 and 64 bits, similar to how it works on the GP reg side.
Because we don't model that zero-extension in the machine description this can cause GCC to move the
results of these instructions to the GP regs just to do a (superfluous) zero-extension.
This patch just adds a pattern to catch these cases. For the testcases we can now generate no zero-extends
or GP<->FP reg moves, whereas before we generated stuff like:
foo_8_32:
        uaddlv  h0, v0.8b
        umov    w1, v0.h[0] // FP<->GP move with zero-extension!
        str     w1, [x0]
        ret

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

gcc/ChangeLog:

	* config/aarch64/aarch64-simd.md
	(*aarch64_<su>addlv<VDQV_L:mode>_ze<GPI:mode>): New pattern.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/simd/addlv_zext.c: New test.

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diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index d42413b0a711fa9dcacd70a2f97fc5c716427881..952df0df0378a14d634e9218ffde877c645c8a28 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -3554,6 +3554,22 @@ (define_insn "aarch64_<su>addlv<mode>"
   [(set_attr "type" "neon_reduc_add<q>")]
 )
 
+;; Zero-extending version of the above.  As these intrinsics produce a scalar
+;; value that may be used by further intrinsics we want to avoid moving the
+;; result into GP regs to do a zero-extension that ADDLV/ADDLP gives for free.
+
+(define_insn "*aarch64_<su>addlv<VDQV_L:mode>_ze<GPI:mode>"
+ [(set (match_operand:GPI 0 "register_operand" "=w")
+       (zero_extend:GPI
+	(unspec:<VWIDE_S>
+	  [(match_operand:VDQV_L 1 "register_operand" "w")]
+	    USADDLV)))]
+ "TARGET_SIMD
+  && (GET_MODE_SIZE (<GPI:MODE>mode) > GET_MODE_SIZE (<VWIDE_S>mode))"
+ "<su>addl<VDQV_L:vp>\\t%<VDQV_L:Vwstype>0<VDQV_L:Vwsuf>, %1.<VDQV_L:Vtype>"
+  [(set_attr "type" "neon_reduc_add<VDQV_L:q>")]
+)
+
 (define_insn "aarch64_<su>addlp<mode>"
  [(set (match_operand:<VDBLW> 0 "register_operand" "=w")
        (unspec:<VDBLW> [(match_operand:VDQV_L 1 "register_operand" "w")]
diff --git a/gcc/testsuite/gcc.target/aarch64/simd/addlv_zext.c b/gcc/testsuite/gcc.target/aarch64/simd/addlv_zext.c
new file mode 100644
index 0000000000000000000000000000000000000000..1bd3c303743b73249c0220df5fb95d4a11b9381c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/simd/addlv_zext.c
@@ -0,0 +1,84 @@
+/* { dg-do compile } */
+/* { dg-additional-options "--save-temps -O1" } */
+/* { dg-final { check-function-bodies "**" "" "" } } */
+
+#include <arm_neon.h>
+
+/*
+** foo_8_32:
+**	uaddlv	h0, v0.8b
+**	str	s0, \[x0\]
+**	ret
+*/
+
+void
+foo_8_32 (uint8x8_t a, uint32_t *res)
+{
+  *res = vaddlv_u8 (a);
+}
+
+/*
+** foo_8_64:
+**	uaddlv	h0, v0.8b
+**	str	d0, \[x0\]
+**	ret
+*/
+
+void
+foo_8_64 (uint8x8_t a, uint64_t *res)
+{
+  *res = vaddlv_u8 (a);
+}
+
+/*
+** foo_16_64:
+**	uaddlv	s0, v0.4h
+**	str	d0, \[x0\]
+**	ret
+*/
+
+void
+foo_16_64 (uint16x4_t a, uint64_t *res)
+{
+  *res = vaddlv_u16 (a);
+}
+
+/*
+** fooq_8_32:
+**	uaddlv	h0, v0.16b
+**	str	s0, \[x0\]
+**	ret
+*/
+
+void
+fooq_8_32 (uint8x16_t a, uint32_t *res)
+{
+  *res = vaddlvq_u8 (a);
+}
+
+/*
+** fooq_8_64:
+**	uaddlv	h0, v0.16b
+**	str	d0, \[x0\]
+**	ret
+*/
+
+void
+fooq_8_64 (uint8x16_t a, uint64_t *res)
+{
+  *res = vaddlvq_u8 (a);
+}
+
+/*
+** fooq_16_64:
+**	uaddlv	s0, v0.8h
+**	str	d0, \[x0\]
+**	ret
+*/
+
+void
+fooq_16_64 (uint16x8_t a, uint64_t *res)
+{
+  *res = vaddlvq_u16 (a);
+}
+