Different bitcode between wllvm and clang

[tttturtle-russ]

Hi, I'm trying to compiler the Linux kernel. I tried both wllvm and clang.
For clang, I just add two arguments to the kernel Makefile.

# add debug info
KBUILD_CFLAGS += -g
# generate bitcode
KBUILD_CFLAGS += -save-temps=obj

and use llvm-link to link all the bitcode files into one. However, this produces a lot of errors when linking, something like:

error: Linking global named 'xxx': symbol multiply defined

Then I change to wllvm, I use extract-bc -b built-in.a to get bitcode and it works well.
However, when I compare the two results, the LLVM IRs are quit different.
This is wllvm output

; Function Attrs: cold fn_ret_thunk_extern noredzone nounwind null_pointer_is_valid optsize sanitize_thread sspstrong
define internal void @mac_hid_exit() #0 section ".exit.text" align 64 !kcfi_type !10 {
  %1 = call ptr @llvm.returnaddress(i32 0)
  call void @__tsan_func_entry(ptr %1)
  call void @__sanitizer_cov_trace_pc() #9
  call void @__tsan_read8(ptr @mac_hid_sysctl_header)
  %2 = load ptr, ptr @mac_hid_sysctl_header, align 8
  call void @unregister_sysctl_table(ptr noundef %2) #10
  call void @__tsan_read4(ptr @mouse_emulate_buttons)
  %3 = load i32, ptr @mouse_emulate_buttons, align 4
  call void @__sanitizer_cov_trace_const_cmp4(i32 0, i32 %3)
  %4 = icmp eq i32 %3, 0
  br i1 %4, label %5, label %6

5:                                                ; preds = %0
  call void @__sanitizer_cov_trace_pc() #9
  br label %8

6:                                                ; preds = %0
  call void @__sanitizer_cov_trace_pc() #9
  call void @input_unregister_handler(ptr noundef nonnull @mac_hid_emumouse_handler) #10
  call void @__tsan_read8(ptr @mac_hid_emumouse_dev)
  %7 = load ptr, ptr @mac_hid_emumouse_dev, align 8
  call void @input_unregister_device(ptr noundef %7) #10
  call void @__tsan_write8(ptr @mac_hid_emumouse_dev)
  store ptr null, ptr @mac_hid_emumouse_dev, align 8
  br label %8

8:                                                ; preds = %5, %6
  call void @__tsan_func_exit()
  ret void
}

This is clang output

; Function Attrs: cold fn_ret_thunk_extern noredzone nounwind null_pointer_is_valid optsize sspstrong
define internal void @mac_hid_exit.10() #0 section ".exit.text" align 16 !dbg !29354 {
  %1 = load ptr, ptr @mac_hid_sysctl_header.12, align 8, !dbg !29355
  call void @unregister_sysctl_table(ptr noundef %1) #15, !dbg !29356
  %2 = load i32, ptr @mouse_emulate_buttons.13, align 4, !dbg !29357
  %3 = icmp ne i32 %2, 0, !dbg !29357
  br i1 %3, label %4, label %5, !dbg !29359

4:                                                ; preds = %0
  call void @mac_hid_stop_emulation.14() #15, !dbg !29360
  br label %5, !dbg !29360

5:                                                ; preds = %4, %0
  ret void, !dbg !29361
}

Any suggestion is appreciated!