[FuncAttrs] volatile memcpy should not be eliminated

[dtcxzyw]

Reproducer: https://godbolt.org/z/n4j66We8h

; bin/opt -O3 test.ll -S
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%struct.S0 = type { i32, i32, i64, i16 }

@g_148 = constant %struct.S0 { i32 568401685, i32 -1, i64 -1, i16 -1 }

define i32 @main() {
entry:
  %call2 = call i32 @func_127()
  ret i32 0
}

define i32 @func_127() {
entry:
  %call241 = call ptr @func_144(ptr null)
  %call58 = call i32 @func_139(ptr %call241)
  ret i32 0
}

define internal i32 @func_139(ptr %p_140) {
entry:
  ret i32 0
}

define ptr @func_144(ptr %p_145) {
entry:
  %agg.tmp.ensured = alloca %struct.S0, align 8
  call void @llvm.memcpy.p0.p0.i64(ptr %agg.tmp.ensured, ptr @g_148, i64 24, i1 true)
  ret ptr %p_145
}

Output:

%struct.S0 = type { i32, i32, i64, i16 }

define noundef i32 @main() local_unnamed_addr #0 {
  ret i32 0
}

define noundef i32 @func_127() local_unnamed_addr #0 {
  ret i32 0
}

define ptr @func_144(ptr readnone returned %p_145) local_unnamed_addr #0 {
  %agg.tmp.ensured = alloca %struct.S0, align 8
  call void @llvm.memcpy.p0.p0.i64(ptr nonnull %agg.tmp.ensured, ptr @g_148, i64 24, i1 true)
  ret ptr %p_145
}

declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg) #1

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) }
attributes #1 = { mustprogress nocallback nofree nounwind willreturn memory(argmem: readwrite) }

The memory effect of func_144 should not be memory(none).