[SVE] Add ISel patterns for "insert undef_nxv#f##, f##, 0"

Differential Revision: https://reviews.llvm.org/D89235

Author: paulwalker-arm

llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td

@@ -2171,6 +2171,19 @@ multiclass sve_prefetch<SDPatternOperator prefetch, ValueType PredTy, Instructio
   def : Pat<(nxv2i64 (vector_insert (nxv2i64 (undef)), (i64 FPR64:$src), 0)),
             (INSERT_SUBREG (nxv2i64 (IMPLICIT_DEF)), FPR64:$src, dsub)>;
 
+  def : Pat<(nxv8f16 (vector_insert (nxv8f16 (undef)), (f16 FPR16:$src), 0)),
+            (INSERT_SUBREG (nxv8f16 (IMPLICIT_DEF)), FPR16:$src, hsub)>;
+  def : Pat<(nxv4f16 (vector_insert (nxv4f16 (undef)), (f16 FPR16:$src), 0)),
+            (INSERT_SUBREG (nxv4f16 (IMPLICIT_DEF)), FPR16:$src, hsub)>;
+  def : Pat<(nxv2f16 (vector_insert (nxv2f16 (undef)), (f16 FPR16:$src), 0)),
+            (INSERT_SUBREG (nxv2f16 (IMPLICIT_DEF)), FPR16:$src, hsub)>;
+  def : Pat<(nxv4f32 (vector_insert (nxv4f32 (undef)), (f32 FPR32:$src), 0)),
+            (INSERT_SUBREG (nxv4f32 (IMPLICIT_DEF)), FPR32:$src, ssub)>;
+  def : Pat<(nxv2f32 (vector_insert (nxv2f32 (undef)), (f32 FPR32:$src), 0)),
+            (INSERT_SUBREG (nxv2f32 (IMPLICIT_DEF)), FPR32:$src, ssub)>;
+  def : Pat<(nxv2f64 (vector_insert (nxv2f64 (undef)), (f64 FPR64:$src), 0)),
+            (INSERT_SUBREG (nxv2f64 (IMPLICIT_DEF)), FPR64:$src, dsub)>;
+
   // Insert scalar into vector[0]
   def : Pat<(nxv16i8 (vector_insert (nxv16i8 ZPR:$vec), (i32 GPR32:$src), 0)),
             (CPY_ZPmR_B ZPR:$vec, (PTRUE_B 1), GPR32:$src)>;

llvm/test/CodeGen/AArch64/sve-insert-element.ll

@@ -223,3 +223,57 @@ define <vscale x 16 x i8> @test_insert3_of_extract1_16xi8(<vscale x 16 x i8> %a,
   %d = insertelement <vscale x 16 x i8> %a, i8 %c, i32 3
   ret <vscale x 16 x i8> %d
 }
+
+define <vscale x 8 x half> @test_insert_into_undef_nxv8f16(half %a) {
+; CHECK-LABEL: test_insert_into_undef_nxv8f16:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $h0 killed $h0 def $z0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 8 x half> undef, half %a, i32 0
+  ret <vscale x 8 x half> %b
+}
+
+define <vscale x 4 x half> @test_insert_into_undef_nxv4f16(half %a) {
+; CHECK-LABEL: test_insert_into_undef_nxv4f16:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $h0 killed $h0 def $z0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 4 x half> undef, half %a, i32 0
+  ret <vscale x 4 x half> %b
+}
+
+define <vscale x 2 x half> @test_insert_into_undef_nxv2f16(half %a) {
+; CHECK-LABEL: test_insert_into_undef_nxv2f16:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $h0 killed $h0 def $z0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 2 x half> undef, half %a, i32 0
+  ret <vscale x 2 x half> %b
+}
+
+define <vscale x 4 x float> @test_insert_into_undef_nxv4f32(float %a) {
+; CHECK-LABEL: test_insert_into_undef_nxv4f32:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $s0 killed $s0 def $z0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 4 x float> undef, float %a, i32 0
+  ret <vscale x 4 x float> %b
+}
+
+define <vscale x 2 x float> @test_insert_into_undef_nxv2f32(float %a) {
+; CHECK-LABEL: test_insert_into_undef_nxv2f32:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $s0 killed $s0 def $z0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 2 x float> undef, float %a, i32 0
+  ret <vscale x 2 x float> %b
+}
+
+define <vscale x 2 x double> @test_insert_into_undef_nxv2f64(double %a) {
+; CHECK-LABEL: test_insert_into_undef_nxv2f64:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    // kill: def $d0 killed $d0 def $z0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 2 x double> undef, double %a, i32 0
+  ret <vscale x 2 x double> %b
+}