From 32dcdb5709c1720df26401ff81a0b71a32cfeb1e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABtan=20Bossu?= <gaetan.bossu@arm.com>
Date: Fri, 19 Dec 2025 13:07:47 +0000
Subject: [PATCH 1/3] [AArch64][ISel] Extend insertelement tests

This in preparation to adding a DAG combiner for turning
INSERT_VECTOR_ELT(undef, ...) -> VECTOR_SPLAT
---
 .../CodeGen/AArch64/sve-insert-element.ll     | 475 +++++++++++++++---
 1 file changed, 411 insertions(+), 64 deletions(-)

diff --git a/llvm/test/CodeGen/AArch64/sve-insert-element.ll b/llvm/test/CodeGen/AArch64/sve-insert-element.ll
index 8ca005a88add3..5cc54929756ff 100644
--- a/llvm/test/CodeGen/AArch64/sve-insert-element.ll
+++ b/llvm/test/CodeGen/AArch64/sve-insert-element.ll
@@ -165,31 +165,378 @@ define <vscale x 16 x i8> @test_lanex_16xi8(<vscale x 16 x i8> %a, i32 %x) {
   ret <vscale x 16 x i8> %b
 }
 
+; TODO: Implement DAG combiner.
+; INSERT_VECTOR_ELT(undef, ...) -> VECTOR_SPLAT
 
-; Redundant lane insert
-define <vscale x 4 x i32> @extract_insert_4xi32(<vscale x 4 x i32> %a) {
-; CHECK-LABEL: extract_insert_4xi32:
+define <vscale x 16 x i8> @test_lanex_16xi8_poison(i8 %e, i32 %x) {
+; CHECK-LABEL: test_lanex_16xi8_poison:
 ; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.b, #0, #1
+; CHECK-NEXT:    mov w8, w1
+; CHECK-NEXT:    ptrue p0.b
+; CHECK-NEXT:    mov z1.b, w8
+; CHECK-NEXT:    cmpeq p0.b, p0/z, z0.b, z1.b
+; CHECK-NEXT:    mov z0.b, p0/m, w0
 ; CHECK-NEXT:    ret
-  %b = extractelement <vscale x 4 x i32> %a, i32 2
-  %c = insertelement <vscale x 4 x i32> %a, i32 %b, i32 2
-  ret <vscale x 4 x i32> %c
+  %b = insertelement <vscale x 16 x i8> poison, i8 %e, i32 %x
+  ret <vscale x 16 x i8> %b
 }
 
-define <vscale x 8 x i16> @test_lane6_undef_8xi16(i16 %a) {
-; CHECK-LABEL: test_lane6_undef_8xi16:
+define <vscale x 16 x i8> @test_lanex_16xi8_poison_imm(i8 %e, i32 %x) {
+; CHECK-LABEL: test_lanex_16xi8_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.b, #0, #1
+; CHECK-NEXT:    mov w8, w1
+; CHECK-NEXT:    ptrue p0.b
+; CHECK-NEXT:    mov z1.b, w8
+; CHECK-NEXT:    mov w8, #5 // =0x5
+; CHECK-NEXT:    cmpeq p0.b, p0/z, z0.b, z1.b
+; CHECK-NEXT:    mov z0.b, p0/m, w8
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 16 x i8> poison, i8 5, i32 %x
+  ret <vscale x 16 x i8> %b
+}
+
+define <vscale x 8 x i16> @test_lanex_8xi16_poison(i16 %e, i32 %x) {
+; CHECK-LABEL: test_lanex_8xi16_poison:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    mov w8, #6 // =0x6
 ; CHECK-NEXT:    index z0.h, #0, #1
+; CHECK-NEXT:    mov w8, w1
 ; CHECK-NEXT:    ptrue p0.h
 ; CHECK-NEXT:    mov z1.h, w8
 ; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
 ; CHECK-NEXT:    mov z0.h, p0/m, w0
 ; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 8 x i16> poison, i16 %a, i32 6
+  %b = insertelement <vscale x 8 x i16> poison, i16 %e, i32 %x
   ret <vscale x 8 x i16> %b
 }
 
+define <vscale x 8 x i16> @test_lanex_8xi16_poison_imm(i32 %x) {
+; CHECK-LABEL: test_lanex_8xi16_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.h, #0, #1
+; CHECK-NEXT:    mov w8, w0
+; CHECK-NEXT:    ptrue p0.h
+; CHECK-NEXT:    mov z1.h, w8
+; CHECK-NEXT:    mov w8, #5 // =0x5
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
+; CHECK-NEXT:    mov z0.h, p0/m, w8
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 8 x i16> poison, i16 5, i32 %x
+  ret <vscale x 8 x i16> %b
+}
+
+define <vscale x 4 x i32> @test_lanex_4xi32_poison(i32 %e, i32 %x) {
+; CHECK-LABEL: test_lanex_4xi32_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.s, #0, #1
+; CHECK-NEXT:    mov w8, w1
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    mov z1.s, w8
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
+; CHECK-NEXT:    mov z0.s, p0/m, w0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 4 x i32> poison, i32 %e, i32 %x
+  ret <vscale x 4 x i32> %b
+}
+
+define <vscale x 4 x i32> @test_lanex_4xi32_poison_imm(i32 %x) {
+; CHECK-LABEL: test_lanex_4xi32_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.s, #0, #1
+; CHECK-NEXT:    mov w8, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    mov z1.s, w8
+; CHECK-NEXT:    mov w8, #5 // =0x5
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
+; CHECK-NEXT:    mov z0.s, p0/m, w8
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 4 x i32> poison, i32 5, i32 %x
+  ret <vscale x 4 x i32> %b
+}
+
+define <vscale x 2 x i64> @test_lanex_2xi64_poison(i64 %e, i32 %x) {
+; CHECK-LABEL: test_lanex_2xi64_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.d, #0, #1
+; CHECK-NEXT:    mov w8, w1
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    mov z1.d, x8
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    mov z0.d, p0/m, x0
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 2 x i64> poison, i64 %e, i32 %x
+  ret <vscale x 2 x i64> %b
+}
+
+define <vscale x 2 x i64> @test_lanex_2xi64_poison_imm(i32 %x) {
+; CHECK-LABEL: test_lanex_2xi64_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.d, #0, #1
+; CHECK-NEXT:    mov w8, w0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    mov z1.d, x8
+; CHECK-NEXT:    mov w8, #5 // =0x5
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    mov z0.d, p0/m, x8
+; CHECK-NEXT:    ret
+  %b = insertelement <vscale x 2 x i64> poison, i64 5, i32 %x
+  ret <vscale x 2 x i64> %b
+}
+
+define <vscale x 2 x half> @test_lanex_nxv2f16_poison(half %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2f16_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.d, #0, #1
+; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x half> poison, half %h, i64 %idx
+  ret <vscale x 2 x half> %res
+}
+
+define <vscale x 2 x half> @test_lanex_nxv2f16_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2f16_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.d, #0, #1
+; CHECK-NEXT:    mov z1.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    fmov h0, #1.50000000
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x half> poison, half 1.5, i64 %idx
+  ret <vscale x 2 x half> %res
+}
+
+define <vscale x 4 x half> @test_lanex_nxv4f16_poison(half %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4f16_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.s, #0, #1
+; CHECK-NEXT:    mov z2.s, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 4 x half> poison, half %h, i64 %idx
+  ret <vscale x 4 x half> %res
+}
+
+define <vscale x 4 x half> @test_lanex_nxv4f16_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4f16_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.s, #0, #1
+; CHECK-NEXT:    mov z1.s, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
+; CHECK-NEXT:    fmov h0, #1.50000000
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 4 x half> poison, half 1.5, i64 %idx
+  ret <vscale x 4 x half> %res
+}
+
+define <vscale x 8 x half> @test_lanex_nxv8f16_poison(half %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv8f16_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.h, #0, #1
+; CHECK-NEXT:    mov z2.h, w0
+; CHECK-NEXT:    ptrue p0.h
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z1.h, z2.h
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 8 x half> poison, half %h, i64 %idx
+  ret <vscale x 8 x half> %res
+}
+
+define <vscale x 8 x half> @test_lanex_nxv8f16_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv8f16_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.h, #0, #1
+; CHECK-NEXT:    mov z1.h, w0
+; CHECK-NEXT:    ptrue p0.h
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
+; CHECK-NEXT:    fmov h0, #1.50000000
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 8 x half> poison, half 1.5, i64 %idx
+  ret <vscale x 8 x half> %res
+}
+
+define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_undef(bfloat %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2bf16_undef:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.d, #0, #1
+; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x bfloat> poison, bfloat %h, i64 %idx
+  ret <vscale x 2 x bfloat> %res
+}
+
+define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_undef_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2bf16_undef_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.d, #0, #1
+; CHECK-NEXT:    mov z1.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    fmov h0, #1.93750000
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x bfloat> poison, bfloat 1.5, i64 %idx
+  ret <vscale x 2 x bfloat> %res
+}
+
+define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_undef(bfloat %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4bf16_undef:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.s, #0, #1
+; CHECK-NEXT:    mov z2.s, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 4 x bfloat> poison, bfloat %h, i64 %idx
+  ret <vscale x 4 x bfloat> %res
+}
+
+define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_undef_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4bf16_undef_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.s, #0, #1
+; CHECK-NEXT:    mov z1.s, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
+; CHECK-NEXT:    fmov h0, #1.93750000
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 4 x bfloat> poison, bfloat 1.5, i64 %idx
+  ret <vscale x 4 x bfloat> %res
+}
+
+define <vscale x 8 x bfloat> @test_lanex_nxv8bf16_poison(bfloat %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv8bf16_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.h, #0, #1
+; CHECK-NEXT:    mov z2.h, w0
+; CHECK-NEXT:    ptrue p0.h
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z1.h, z2.h
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 8 x bfloat> poison, bfloat %h, i64 %idx
+  ret <vscale x 8 x bfloat> %res
+}
+
+define <vscale x 8 x bfloat> @test_lanex_nxv8bf16_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv8bf16_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.h, #0, #1
+; CHECK-NEXT:    mov z1.h, w0
+; CHECK-NEXT:    ptrue p0.h
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
+; CHECK-NEXT:    fmov h0, #1.93750000
+; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 8 x bfloat> poison, bfloat 1.5, i64 %idx
+  ret <vscale x 8 x bfloat> %res
+}
+
+define <vscale x 2 x float> @test_lanex_nxv2f32_poison(float %f, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2f32_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.d, #0, #1
+; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
+; CHECK-NEXT:    mov z0.s, p0/m, s0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x float> poison, float %f, i64 %idx
+  ret <vscale x 2 x float> %res
+}
+
+define <vscale x 2 x float> @test_lanex_nxv2f32_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2f32_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.d, #0, #1
+; CHECK-NEXT:    mov z1.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    fmov s0, #1.50000000
+; CHECK-NEXT:    mov z0.s, p0/m, s0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x float> poison, float 1.5, i64 %idx
+  ret <vscale x 2 x float> %res
+}
+
+define <vscale x 4 x float> @test_lanex_nxv4f32_poison(float %f, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4f32_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.s, #0, #1
+; CHECK-NEXT:    mov z2.s, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
+; CHECK-NEXT:    mov z0.s, p0/m, s0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 4 x float> poison, float %f, i64 %idx
+  ret <vscale x 4 x float> %res
+}
+
+define <vscale x 4 x float> @test_lanex_nxv4f32_poison_imm(float %f, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4f32_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.s, #0, #1
+; CHECK-NEXT:    mov z1.s, w0
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
+; CHECK-NEXT:    fmov s0, #1.50000000
+; CHECK-NEXT:    mov z0.s, p0/m, s0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 4 x float> poison, float 1.5, i64 %idx
+  ret <vscale x 4 x float> %res
+}
+
+define <vscale x 2 x double> @test_lanex_nxv2f64_poison(double %d, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2f64_poison:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z1.d, #0, #1
+; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
+; CHECK-NEXT:    mov z0.d, p0/m, d0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x double> poison, double %d, i64 %idx
+  ret <vscale x 2 x double> %res
+}
+
+define <vscale x 2 x double> @test_lanex_nxv2f64_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2f64_poison_imm:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    index z0.d, #0, #1
+; CHECK-NEXT:    mov z1.d, x0
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    fmov d0, #1.50000000
+; CHECK-NEXT:    mov z0.d, p0/m, d0
+; CHECK-NEXT:    ret
+  %res = insertelement <vscale x 2 x double> poison, double 1.5, i64 %idx
+  ret <vscale x 2 x double> %res
+}
+
+; Redundant lane insert
+define <vscale x 4 x i32> @extract_insert_4xi32(<vscale x 4 x i32> %a) {
+; CHECK-LABEL: extract_insert_4xi32:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ret
+  %b = extractelement <vscale x 4 x i32> %a, i32 2
+  %c = insertelement <vscale x 4 x i32> %a, i32 %b, i32 2
+  ret <vscale x 4 x i32> %c
+}
+
 define <vscale x 16 x i8> @test_lane0_undef_16xi8(i8 %a) {
 ; CHECK-LABEL: test_lane0_undef_16xi8:
 ; CHECK:       // %bb.0:
@@ -326,120 +673,120 @@ define <vscale x 2 x double> @test_insert_into_undef_nxv2f64(double %a) {
 }
 
 ; Insert scalar at index
-define <vscale x 2 x half> @test_insert_with_index_nxv2f16(half %h, i64 %idx) {
+define <vscale x 2 x half> @test_insert_with_index_nxv2f16(<vscale x 2 x half> %a, half %h, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv2f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    index z2.d, #0, #1
+; CHECK-NEXT:    mov z3.d, x0
 ; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z2.d, z3.d
+; CHECK-NEXT:    mov z0.h, p0/m, h1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x half> poison, half %h, i64 %idx
+  %res = insertelement <vscale x 2 x half> %a, half %h, i64 %idx
   ret <vscale x 2 x half> %res
 }
 
-define <vscale x 4 x half> @test_insert_with_index_nxv4f16(half %h, i64 %idx) {
+define <vscale x 4 x half> @test_insert_with_index_nxv4f16(<vscale x 4 x half> %a, half %h, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv4f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.s, #0, #1
-; CHECK-NEXT:    mov z2.s, w0
+; CHECK-NEXT:    index z2.s, #0, #1
+; CHECK-NEXT:    mov z3.s, w0
 ; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
-; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z2.s, z3.s
+; CHECK-NEXT:    mov z0.h, p0/m, h1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x half> poison, half %h, i64 %idx
+  %res = insertelement <vscale x 4 x half> %a, half %h, i64 %idx
   ret <vscale x 4 x half> %res
 }
 
-define <vscale x 8 x half> @test_insert_with_index_nxv8f16(half %h, i64 %idx) {
+define <vscale x 8 x half> @test_insert_with_index_nxv8f16(<vscale x 8 x half> %a, half %h, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv8f16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.h, #0, #1
-; CHECK-NEXT:    mov z2.h, w0
+; CHECK-NEXT:    index z2.h, #0, #1
+; CHECK-NEXT:    mov z3.h, w0
 ; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z1.h, z2.h
-; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z2.h, z3.h
+; CHECK-NEXT:    mov z0.h, p0/m, h1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 8 x half> poison, half %h, i64 %idx
+  %res = insertelement <vscale x 8 x half> %a, half %h, i64 %idx
   ret <vscale x 8 x half> %res
 }
 
-define <vscale x 2 x bfloat> @test_insert_with_index_nxv2bf16(bfloat %h, i64 %idx) {
+define <vscale x 2 x bfloat> @test_insert_with_index_nxv2bf16(<vscale x 2 x bfloat> %a, bfloat %h, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv2bf16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    index z2.d, #0, #1
+; CHECK-NEXT:    mov z3.d, x0
 ; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z2.d, z3.d
+; CHECK-NEXT:    mov z0.h, p0/m, h1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x bfloat> poison, bfloat %h, i64 %idx
+  %res = insertelement <vscale x 2 x bfloat> %a, bfloat %h, i64 %idx
   ret <vscale x 2 x bfloat> %res
 }
 
-define <vscale x 4 x bfloat> @test_insert_with_index_nxv4bf16(bfloat %h, i64 %idx) {
+define <vscale x 4 x bfloat> @test_insert_with_index_nxv4bf16(<vscale x 4 x bfloat> %a, bfloat %h, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv4bf16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.s, #0, #1
-; CHECK-NEXT:    mov z2.s, w0
+; CHECK-NEXT:    index z2.s, #0, #1
+; CHECK-NEXT:    mov z3.s, w0
 ; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
-; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z2.s, z3.s
+; CHECK-NEXT:    mov z0.h, p0/m, h1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x bfloat> poison, bfloat %h, i64 %idx
+  %res = insertelement <vscale x 4 x bfloat> %a, bfloat %h, i64 %idx
   ret <vscale x 4 x bfloat> %res
 }
 
-define <vscale x 8 x bfloat> @test_insert_with_index_nxv8bf16(bfloat %h, i64 %idx) {
+define <vscale x 8 x bfloat> @test_insert_with_index_nxv8bf16(<vscale x 8 x bfloat> %a, bfloat %h, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv8bf16:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.h, #0, #1
-; CHECK-NEXT:    mov z2.h, w0
+; CHECK-NEXT:    index z2.h, #0, #1
+; CHECK-NEXT:    mov z3.h, w0
 ; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z1.h, z2.h
-; CHECK-NEXT:    mov z0.h, p0/m, h0
+; CHECK-NEXT:    cmpeq p0.h, p0/z, z2.h, z3.h
+; CHECK-NEXT:    mov z0.h, p0/m, h1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 8 x bfloat> poison, bfloat %h, i64 %idx
+  %res = insertelement <vscale x 8 x bfloat> %a, bfloat %h, i64 %idx
   ret <vscale x 8 x bfloat> %res
 }
 
-define <vscale x 2 x float> @test_insert_with_index_nxv2f32(float %f, i64 %idx) {
+define <vscale x 2 x float> @test_insert_with_index_nxv2f32(<vscale x 2 x float> %a, float %f, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv2f32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    index z2.d, #0, #1
+; CHECK-NEXT:    mov z3.d, x0
 ; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.s, p0/m, s0
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z2.d, z3.d
+; CHECK-NEXT:    mov z0.s, p0/m, s1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x float> poison, float %f, i64 %idx
+  %res = insertelement <vscale x 2 x float> %a, float %f, i64 %idx
   ret <vscale x 2 x float> %res
 }
 
-define <vscale x 4 x float> @test_insert_with_index_nxv4f32(float %f, i64 %idx) {
+define <vscale x 4 x float> @test_insert_with_index_nxv4f32(<vscale x 4 x float> %a, float %f, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv4f32:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.s, #0, #1
-; CHECK-NEXT:    mov z2.s, w0
+; CHECK-NEXT:    index z2.s, #0, #1
+; CHECK-NEXT:    mov z3.s, w0
 ; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
-; CHECK-NEXT:    mov z0.s, p0/m, s0
+; CHECK-NEXT:    cmpeq p0.s, p0/z, z2.s, z3.s
+; CHECK-NEXT:    mov z0.s, p0/m, s1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x float> poison, float %f, i64 %idx
+  %res = insertelement <vscale x 4 x float> %a, float %f, i64 %idx
   ret <vscale x 4 x float> %res
 }
 
-define <vscale x 2 x double> @test_insert_with_index_nxv2f64(double %d, i64 %idx) {
+define <vscale x 2 x double> @test_insert_with_index_nxv2f64(<vscale x 2 x double> %a, double %d, i64 %idx) {
 ; CHECK-LABEL: test_insert_with_index_nxv2f64:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
+; CHECK-NEXT:    index z2.d, #0, #1
+; CHECK-NEXT:    mov z3.d, x0
 ; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.d, p0/m, d0
+; CHECK-NEXT:    cmpeq p0.d, p0/z, z2.d, z3.d
+; CHECK-NEXT:    mov z0.d, p0/m, d1
 ; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x double> poison, double %d, i64 %idx
+  %res = insertelement <vscale x 2 x double> %a, double %d, i64 %idx
   ret <vscale x 2 x double> %res
 }
 

From a1cdffd67329f8e577dc3e8b7d401c8aa1590e3f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABtan=20Bossu?= <gaetan.bossu@arm.com>
Date: Fri, 19 Dec 2025 13:26:17 +0000
Subject: [PATCH 2/3] Rename undef -> poison

---
 .../test/CodeGen/AArch64/sve-insert-element.ll | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/llvm/test/CodeGen/AArch64/sve-insert-element.ll b/llvm/test/CodeGen/AArch64/sve-insert-element.ll
index 5cc54929756ff..2b8d660797493 100644
--- a/llvm/test/CodeGen/AArch64/sve-insert-element.ll
+++ b/llvm/test/CodeGen/AArch64/sve-insert-element.ll
@@ -166,7 +166,7 @@ define <vscale x 16 x i8> @test_lanex_16xi8(<vscale x 16 x i8> %a, i32 %x) {
 }
 
 ; TODO: Implement DAG combiner.
-; INSERT_VECTOR_ELT(undef, ...) -> VECTOR_SPLAT
+; INSERT_VECTOR_ELT(poison, ...) -> VECTOR_SPLAT
 
 define <vscale x 16 x i8> @test_lanex_16xi8_poison(i8 %e, i32 %x) {
 ; CHECK-LABEL: test_lanex_16xi8_poison:
@@ -365,8 +365,8 @@ define <vscale x 8 x half> @test_lanex_nxv8f16_poison_imm(i64 %idx) {
   ret <vscale x 8 x half> %res
 }
 
-define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_undef(bfloat %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2bf16_undef:
+define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_poison(bfloat %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2bf16_poison:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    index z1.d, #0, #1
 ; CHECK-NEXT:    mov z2.d, x0
@@ -378,8 +378,8 @@ define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_undef(bfloat %h, i64 %idx) {
   ret <vscale x 2 x bfloat> %res
 }
 
-define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_undef_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2bf16_undef_imm:
+define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv2bf16_poison_imm:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    index z0.d, #0, #1
 ; CHECK-NEXT:    mov z1.d, x0
@@ -392,8 +392,8 @@ define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_undef_imm(i64 %idx) {
   ret <vscale x 2 x bfloat> %res
 }
 
-define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_undef(bfloat %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4bf16_undef:
+define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_poison(bfloat %h, i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4bf16_poison:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    index z1.s, #0, #1
 ; CHECK-NEXT:    mov z2.s, w0
@@ -405,8 +405,8 @@ define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_undef(bfloat %h, i64 %idx) {
   ret <vscale x 4 x bfloat> %res
 }
 
-define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_undef_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4bf16_undef_imm:
+define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_poison_imm(i64 %idx) {
+; CHECK-LABEL: test_lanex_nxv4bf16_poison_imm:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    index z0.s, #0, #1
 ; CHECK-NEXT:    mov z1.s, w0

From e4f7614e4e9f32c1a24814ce275cfa14ed0027c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABtan=20Bossu?= <gaetan.bossu@arm.com>
Date: Fri, 19 Dec 2025 15:02:12 +0000
Subject: [PATCH 3/3] Only keep a couple of tests for the DAG combiner.

This treats the IR->asm test as a unit test.
---
 .../CodeGen/AArch64/sve-insert-element.ll     | 335 +-----------------
 1 file changed, 4 insertions(+), 331 deletions(-)

diff --git a/llvm/test/CodeGen/AArch64/sve-insert-element.ll b/llvm/test/CodeGen/AArch64/sve-insert-element.ll
index 2b8d660797493..a897850c1365d 100644
--- a/llvm/test/CodeGen/AArch64/sve-insert-element.ll
+++ b/llvm/test/CodeGen/AArch64/sve-insert-element.ll
@@ -166,7 +166,9 @@ define <vscale x 16 x i8> @test_lanex_16xi8(<vscale x 16 x i8> %a, i32 %x) {
 }
 
 ; TODO: Implement DAG combiner.
-; INSERT_VECTOR_ELT(poison, ...) -> VECTOR_SPLAT
+; Test the INSERT_VECTOR_ELT(poison, ...) -> VECTOR_SPLAT combiner
+; <vscale x 16 x i8> is used as a proxy for testing using IR, but the combiner
+; is agnostic of the element type.
 
 define <vscale x 16 x i8> @test_lanex_16xi8_poison(i8 %e, i32 %x) {
 ; CHECK-LABEL: test_lanex_16xi8_poison:
@@ -197,336 +199,6 @@ define <vscale x 16 x i8> @test_lanex_16xi8_poison_imm(i8 %e, i32 %x) {
   ret <vscale x 16 x i8> %b
 }
 
-define <vscale x 8 x i16> @test_lanex_8xi16_poison(i16 %e, i32 %x) {
-; CHECK-LABEL: test_lanex_8xi16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.h, #0, #1
-; CHECK-NEXT:    mov w8, w1
-; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    mov z1.h, w8
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
-; CHECK-NEXT:    mov z0.h, p0/m, w0
-; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 8 x i16> poison, i16 %e, i32 %x
-  ret <vscale x 8 x i16> %b
-}
-
-define <vscale x 8 x i16> @test_lanex_8xi16_poison_imm(i32 %x) {
-; CHECK-LABEL: test_lanex_8xi16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.h, #0, #1
-; CHECK-NEXT:    mov w8, w0
-; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    mov z1.h, w8
-; CHECK-NEXT:    mov w8, #5 // =0x5
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
-; CHECK-NEXT:    mov z0.h, p0/m, w8
-; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 8 x i16> poison, i16 5, i32 %x
-  ret <vscale x 8 x i16> %b
-}
-
-define <vscale x 4 x i32> @test_lanex_4xi32_poison(i32 %e, i32 %x) {
-; CHECK-LABEL: test_lanex_4xi32_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.s, #0, #1
-; CHECK-NEXT:    mov w8, w1
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    mov z1.s, w8
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
-; CHECK-NEXT:    mov z0.s, p0/m, w0
-; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 4 x i32> poison, i32 %e, i32 %x
-  ret <vscale x 4 x i32> %b
-}
-
-define <vscale x 4 x i32> @test_lanex_4xi32_poison_imm(i32 %x) {
-; CHECK-LABEL: test_lanex_4xi32_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.s, #0, #1
-; CHECK-NEXT:    mov w8, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    mov z1.s, w8
-; CHECK-NEXT:    mov w8, #5 // =0x5
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
-; CHECK-NEXT:    mov z0.s, p0/m, w8
-; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 4 x i32> poison, i32 5, i32 %x
-  ret <vscale x 4 x i32> %b
-}
-
-define <vscale x 2 x i64> @test_lanex_2xi64_poison(i64 %e, i32 %x) {
-; CHECK-LABEL: test_lanex_2xi64_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.d, #0, #1
-; CHECK-NEXT:    mov w8, w1
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    mov z1.d, x8
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
-; CHECK-NEXT:    mov z0.d, p0/m, x0
-; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 2 x i64> poison, i64 %e, i32 %x
-  ret <vscale x 2 x i64> %b
-}
-
-define <vscale x 2 x i64> @test_lanex_2xi64_poison_imm(i32 %x) {
-; CHECK-LABEL: test_lanex_2xi64_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.d, #0, #1
-; CHECK-NEXT:    mov w8, w0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    mov z1.d, x8
-; CHECK-NEXT:    mov w8, #5 // =0x5
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
-; CHECK-NEXT:    mov z0.d, p0/m, x8
-; CHECK-NEXT:    ret
-  %b = insertelement <vscale x 2 x i64> poison, i64 5, i32 %x
-  ret <vscale x 2 x i64> %b
-}
-
-define <vscale x 2 x half> @test_lanex_nxv2f16_poison(half %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2f16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x half> poison, half %h, i64 %idx
-  ret <vscale x 2 x half> %res
-}
-
-define <vscale x 2 x half> @test_lanex_nxv2f16_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2f16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.d, #0, #1
-; CHECK-NEXT:    mov z1.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
-; CHECK-NEXT:    fmov h0, #1.50000000
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x half> poison, half 1.5, i64 %idx
-  ret <vscale x 2 x half> %res
-}
-
-define <vscale x 4 x half> @test_lanex_nxv4f16_poison(half %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4f16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.s, #0, #1
-; CHECK-NEXT:    mov z2.s, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x half> poison, half %h, i64 %idx
-  ret <vscale x 4 x half> %res
-}
-
-define <vscale x 4 x half> @test_lanex_nxv4f16_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4f16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.s, #0, #1
-; CHECK-NEXT:    mov z1.s, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
-; CHECK-NEXT:    fmov h0, #1.50000000
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x half> poison, half 1.5, i64 %idx
-  ret <vscale x 4 x half> %res
-}
-
-define <vscale x 8 x half> @test_lanex_nxv8f16_poison(half %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv8f16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.h, #0, #1
-; CHECK-NEXT:    mov z2.h, w0
-; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z1.h, z2.h
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 8 x half> poison, half %h, i64 %idx
-  ret <vscale x 8 x half> %res
-}
-
-define <vscale x 8 x half> @test_lanex_nxv8f16_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv8f16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.h, #0, #1
-; CHECK-NEXT:    mov z1.h, w0
-; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
-; CHECK-NEXT:    fmov h0, #1.50000000
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 8 x half> poison, half 1.5, i64 %idx
-  ret <vscale x 8 x half> %res
-}
-
-define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_poison(bfloat %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2bf16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x bfloat> poison, bfloat %h, i64 %idx
-  ret <vscale x 2 x bfloat> %res
-}
-
-define <vscale x 2 x bfloat> @test_lanex_nxv2bf16_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2bf16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.d, #0, #1
-; CHECK-NEXT:    mov z1.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
-; CHECK-NEXT:    fmov h0, #1.93750000
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x bfloat> poison, bfloat 1.5, i64 %idx
-  ret <vscale x 2 x bfloat> %res
-}
-
-define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_poison(bfloat %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4bf16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.s, #0, #1
-; CHECK-NEXT:    mov z2.s, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x bfloat> poison, bfloat %h, i64 %idx
-  ret <vscale x 4 x bfloat> %res
-}
-
-define <vscale x 4 x bfloat> @test_lanex_nxv4bf16_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4bf16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.s, #0, #1
-; CHECK-NEXT:    mov z1.s, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
-; CHECK-NEXT:    fmov h0, #1.93750000
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x bfloat> poison, bfloat 1.5, i64 %idx
-  ret <vscale x 4 x bfloat> %res
-}
-
-define <vscale x 8 x bfloat> @test_lanex_nxv8bf16_poison(bfloat %h, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv8bf16_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.h, #0, #1
-; CHECK-NEXT:    mov z2.h, w0
-; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z1.h, z2.h
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 8 x bfloat> poison, bfloat %h, i64 %idx
-  ret <vscale x 8 x bfloat> %res
-}
-
-define <vscale x 8 x bfloat> @test_lanex_nxv8bf16_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv8bf16_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.h, #0, #1
-; CHECK-NEXT:    mov z1.h, w0
-; CHECK-NEXT:    ptrue p0.h
-; CHECK-NEXT:    cmpeq p0.h, p0/z, z0.h, z1.h
-; CHECK-NEXT:    fmov h0, #1.93750000
-; CHECK-NEXT:    mov z0.h, p0/m, h0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 8 x bfloat> poison, bfloat 1.5, i64 %idx
-  ret <vscale x 8 x bfloat> %res
-}
-
-define <vscale x 2 x float> @test_lanex_nxv2f32_poison(float %f, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2f32_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.s, p0/m, s0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x float> poison, float %f, i64 %idx
-  ret <vscale x 2 x float> %res
-}
-
-define <vscale x 2 x float> @test_lanex_nxv2f32_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2f32_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.d, #0, #1
-; CHECK-NEXT:    mov z1.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
-; CHECK-NEXT:    fmov s0, #1.50000000
-; CHECK-NEXT:    mov z0.s, p0/m, s0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x float> poison, float 1.5, i64 %idx
-  ret <vscale x 2 x float> %res
-}
-
-define <vscale x 4 x float> @test_lanex_nxv4f32_poison(float %f, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4f32_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.s, #0, #1
-; CHECK-NEXT:    mov z2.s, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z1.s, z2.s
-; CHECK-NEXT:    mov z0.s, p0/m, s0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x float> poison, float %f, i64 %idx
-  ret <vscale x 4 x float> %res
-}
-
-define <vscale x 4 x float> @test_lanex_nxv4f32_poison_imm(float %f, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv4f32_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.s, #0, #1
-; CHECK-NEXT:    mov z1.s, w0
-; CHECK-NEXT:    ptrue p0.s
-; CHECK-NEXT:    cmpeq p0.s, p0/z, z0.s, z1.s
-; CHECK-NEXT:    fmov s0, #1.50000000
-; CHECK-NEXT:    mov z0.s, p0/m, s0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 4 x float> poison, float 1.5, i64 %idx
-  ret <vscale x 4 x float> %res
-}
-
-define <vscale x 2 x double> @test_lanex_nxv2f64_poison(double %d, i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2f64_poison:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z1.d, #0, #1
-; CHECK-NEXT:    mov z2.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z1.d, z2.d
-; CHECK-NEXT:    mov z0.d, p0/m, d0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x double> poison, double %d, i64 %idx
-  ret <vscale x 2 x double> %res
-}
-
-define <vscale x 2 x double> @test_lanex_nxv2f64_poison_imm(i64 %idx) {
-; CHECK-LABEL: test_lanex_nxv2f64_poison_imm:
-; CHECK:       // %bb.0:
-; CHECK-NEXT:    index z0.d, #0, #1
-; CHECK-NEXT:    mov z1.d, x0
-; CHECK-NEXT:    ptrue p0.d
-; CHECK-NEXT:    cmpeq p0.d, p0/z, z0.d, z1.d
-; CHECK-NEXT:    fmov d0, #1.50000000
-; CHECK-NEXT:    mov z0.d, p0/m, d0
-; CHECK-NEXT:    ret
-  %res = insertelement <vscale x 2 x double> poison, double 1.5, i64 %idx
-  ret <vscale x 2 x double> %res
-}
-
 ; Redundant lane insert
 define <vscale x 4 x i32> @extract_insert_4xi32(<vscale x 4 x i32> %a) {
 ; CHECK-LABEL: extract_insert_4xi32:
@@ -537,6 +209,7 @@ define <vscale x 4 x i32> @extract_insert_4xi32(<vscale x 4 x i32> %a) {
   ret <vscale x 4 x i32> %c
 }
 
+; Inserting lane 0 into poison uses fmov instead of broadcasting to all lanes
 define <vscale x 16 x i8> @test_lane0_undef_16xi8(i8 %a) {
 ; CHECK-LABEL: test_lane0_undef_16xi8:
 ; CHECK:       // %bb.0: