Hi all,

This merges vector multiplies and adds into a single mla instruction when the multiplication is done by a scalar.

Currently, for the following:

    typedef int __attribute__((vector_size(16))) vec;

    vec
    mla0(vec v0, vec v1, vec v2)
    {
      return v0 + v1 * v2[0];
    }

    vec
    mla1(vec v0, vec v1, int v2)
    {
      return v0 + v1 * c;
    }

The function `mla0` outputs a multiply accumulate by element instruction. `mla1` outputs two vector operations (multiply followed by add). That is, we currently have:

    mla0:
        mla    v0.4s, v1.4s, v2.s[0]
        ret

    mla1:
        fmov   s2, w0
        mul    v1.4s, v1.4s, v2.s[0]
        add    v0.4s, v1.4s, v0.4s
        ret

This patch replaces this with something similar to `mla0`:

    mla1:
        fmov   s2, w0
        mla    v0.4s, v1.4s, v2.s[0]

This is also done for the identical case for a multiply followed by a subtract of vectors with an integer operand on the multiply. Also add testcases for this.

Bootstrap and testsuite run on aarch64. OK for trunk?

Jackson

Changelog entry:

gcc/

2017-06-06  Jackson Woodruff <jackson.woodr...@arm.com>

        * config/aarch64/aarch64-simd.md (aarch64_mla_elt_merge<mode>,

        aarch64_mls_elt_merge<mode>, aarch64_fma4_elt_merge<mode>,

        aarch64_fnma_elt_merge<mode>): New define_insns to generate

        multiply accumulate instructions for unmerged

        multiply add vector instructions.


gcc/testsuite/

2017-06-06  Jackson Woodruff <jackson.woodr...@arm.com>

        * gcc.target/aarch64/simd/vmla_elem_1.c: New.

diff --git a/gcc/config/aarch64/aarch64-simd.md 
b/gcc/config/aarch64/aarch64-simd.md
index 
1cb6eeb318716aadacb84a44aa2062d486e0186b..ab1aa5ab84577b3cbddd1eb0e40d29e9b2aa4b42
 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -1033,6 +1033,18 @@
   [(set_attr "type" "neon_mla_<Vetype>_scalar<q>")]
 )
 
+(define_insn "*aarch64_mla_elt_merge<mode>"
+  [(set (match_operand:VDQHS 0 "register_operand" "=w")
+       (plus:VDQHS
+         (mult:VDQHS (vec_duplicate:VDQHS
+                 (match_operand:<VEL> 1 "register_operand" "w"))
+               (match_operand:VDQHS 2 "register_operand" "w"))
+         (match_operand:VDQHS 3 "register_operand" "0")))]
+ "TARGET_SIMD"
+ "mla\t%0.<Vtype>, %2.<Vtype>, %1.<Vetype>[0]"
+  [(set_attr "type" "neon_mla_<Vetype>_scalar<q>")]
+)
+
 (define_insn "aarch64_mls<mode>"
  [(set (match_operand:VDQ_BHSI 0 "register_operand" "=w")
        (minus:VDQ_BHSI (match_operand:VDQ_BHSI 1 "register_operand" "0")
@@ -1080,6 +1092,18 @@
   [(set_attr "type" "neon_mla_<Vetype>_scalar<q>")]
 )
 
+(define_insn "*aarch64_mls_elt_merge<mode>"
+  [(set (match_operand:VDQHS 0 "register_operand" "=w")
+       (minus:VDQHS
+         (match_operand:VDQHS 1 "register_operand" "0")
+         (mult:VDQHS (vec_duplicate:VDQHS
+                 (match_operand:<VEL> 2 "register_operand" "w"))
+               (match_operand:VDQHS 3 "register_operand" "w"))))]
+  "TARGET_SIMD"
+  "mls\t%0.<Vtype>, %3.<Vtype>, %2.<Vetype>[0]"
+  [(set_attr "type" "neon_mla_<Vetype>_scalar<q>")]
+)
+
 ;; Max/Min operations.
 (define_insn "<su><maxmin><mode>3"
  [(set (match_operand:VDQ_BHSI 0 "register_operand" "=w")
diff --git a/gcc/testsuite/gcc.target/aarch64/simd/vmla_elem_1.c 
b/gcc/testsuite/gcc.target/aarch64/simd/vmla_elem_1.c
index 
e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..df777581ab43b9b9e20b61f3f8d46193bdfda5fb
 100644
--- a/gcc/testsuite/gcc.target/aarch64/simd/vmla_elem_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/simd/vmla_elem_1.c
@@ -0,0 +1,67 @@
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+typedef short int __attribute__ ((vector_size (16))) v8hi;
+
+v8hi
+mla8hi (v8hi v0, v8hi v1, short int v2)
+{
+  /* { dg-final { scan-assembler "mla\\tv\[0-9\]\+\\.8h, v\[0-9\]\+\\.8h, 
v\[0-9\]\+\\.h\\\[0\\\]" } } */
+  return v0 + v1 * v2;
+}
+
+
+v8hi
+mls8hi (v8hi v0, v8hi v1, short int v2)
+{
+  /* { dg-final { scan-assembler "mls\\tv\[0-9\]\+\\.8h, v\[0-9\]\+\\.8h, 
v\[0-9\]\+\\.h\\\[0\\\]" } } */
+  return v0 - v1 * v2;
+}
+
+typedef short int __attribute__ ((vector_size (8))) v4hi;
+
+v4hi
+mla4hi (v4hi v0, v4hi v1, short int v2)
+{
+  /* { dg-final { scan-assembler "mla\\tv\[0-9\]\+\\.4h, v\[0-9\]\+\\.4h, 
v\[0-9\]\+\\.h\\\[0\\\]" } } */
+  return v0 + v1 * v2;
+}
+
+v4hi
+mls4hi (v4hi v0, v4hi v1, short int v2)
+{
+  /* { dg-final { scan-assembler "mls\\tv\[0-9\]\+\\.4h, v\[0-9\]\+\\.4h, 
v\[0-9\]\+\\.h\\\[0\\\]" } } */
+  return v0 - v1 * v2;
+}
+
+typedef int __attribute__ ((vector_size (16))) v4si;
+
+v4si
+mla4si (v4si v0, v4si v1, int v2)
+{
+  /* { dg-final { scan-assembler "mla\\tv\[0-9\]\+\\.4s, v\[0-9\]\+\\.4s, 
v\[0-9\]\+\\.s\\\[0\\\]" } } */
+  return v0 + v1 * v2;
+}
+
+v4si
+mls4si (v4si v0, v4si v1, int v2)
+{
+  /* { dg-final { scan-assembler "mls\\tv\[0-9\]\+\\.4s, v\[0-9\]\+\\.4s, 
v\[0-9\]\+\\.s\\\[0\\\]" } } */
+  return v0 - v1 * v2;
+}
+
+typedef int __attribute__((vector_size (8))) v2si;
+
+v2si
+mla2si (v2si v0, v2si v1, int v2)
+{
+  /* { dg-final { scan-assembler "mla\\tv\[0-9\]\+\\.2s, v\[0-9\]\+\\.2s, 
v\[0-9\]\+\\.s\\\[0\\\]" } } */
+  return v0 + v1 * v2;
+}
+
+v2si
+mls2si (v2si v0, v2si v1, int v2)
+{
+  /* { dg-final { scan-assembler "mls\\tv\[0-9\]\+\\.2s, v\[0-9\]\+\\.2s, 
v\[0-9\]\+\\.s\\\[0\\\]" } } */
+  return v0 - v1 * v2;
+}

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