This backport contains 1 patch from gcc main stream tree. 
The commit id of these patchs list as following in the order of time.

0001-vect-ICE-in-vectorizable_load-at-tree-vect-stmts.c-9.patch:
f14b41d27124601284347a10d496362c8b4b8e1c

diff -Nurp a/gcc/testsuite/gcc.target/aarch64/pr94398.c b/gcc/testsuite/gcc.target/aarch64/pr94398.c
--- a/gcc/testsuite/gcc.target/aarch64/pr94398.c	1970-01-01 08:00:00.000000000 +0800
+++ b/gcc/testsuite/gcc.target/aarch64/pr94398.c	2020-04-17 17:15:58.176000000 +0800
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-loop-vectorize -funsafe-math-optimizations -march=armv8.2-a+sve -mstrict-align" } */
+
+float
+foo(long n, float *x, int inc_x,
+            float *y, int inc_y)
+{
+  float dot = 0.0;
+  int ix = 0, iy = 0;
+
+  if (n < 0) {
+    return dot;
+  }
+
+  int i = 0;
+  while (i < n) {
+    dot += y[iy] * x[ix];
+    ix  += inc_x;
+    iy  += inc_y;
+    i++;
+  }
+
+  return dot;
+}
diff -Nurp a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
--- a/gcc/tree-vect-stmts.c	2020-04-17 17:10:14.796000000 +0800
+++ b/gcc/tree-vect-stmts.c	2020-04-17 17:15:08.611850850 +0800
@@ -7025,8 +7025,14 @@ vectorizable_store (stmt_vec_info stmt_i
   auto_vec<tree> dr_chain (group_size);
   oprnds.create (group_size);
 
-  alignment_support_scheme
-    = vect_supportable_dr_alignment (first_dr_info, false);
+  /* Gather-scatter accesses perform only component accesses, alignment
+     is irrelevant for them.  */
+  if (memory_access_type == VMAT_GATHER_SCATTER)
+    alignment_support_scheme = dr_unaligned_supported;
+  else
+    alignment_support_scheme
+      = vect_supportable_dr_alignment (first_dr_info, false);
+
   gcc_assert (alignment_support_scheme);
   vec_loop_masks *loop_masks
     = (loop_vinfo && LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
@@ -8162,8 +8168,14 @@ vectorizable_load (stmt_vec_info stmt_in
       ref_type = reference_alias_ptr_type (DR_REF (first_dr_info->dr));
     }
 
-  alignment_support_scheme
-    = vect_supportable_dr_alignment (first_dr_info, false);
+  /* Gather-scatter accesses perform only component accesses, alignment
+     is irrelevant for them.  */
+  if (memory_access_type == VMAT_GATHER_SCATTER)
+    alignment_support_scheme = dr_unaligned_supported;
+  else
+    alignment_support_scheme
+      = vect_supportable_dr_alignment (first_dr_info, false);
+
   gcc_assert (alignment_support_scheme);
   vec_loop_masks *loop_masks
     = (loop_vinfo && LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)