LLVM global constructor is not called for ATmel processors

Question

I have compiled a cpp code and downloaded it to Arduino Uno for blinking an LED. The code works fine. However, when I convert it to .ll and from .ll to an object file then hex and upload, the code stops working. No LED blinks by the Arduino.

If I address the ports directly:

typedef unsigned char uint8_t;
typedef uint8_t * volatile port_type;

const port_type portB = (port_type) 0x25;
const port_type ddrB = (port_type) 0x24;

it will work fine but if I initialize port addressed via global constructor, it does not work:

int getPortB() {return 0x25;}
int getDdrB() {return 0x24;}

const port_type portB = (port_type) getPortB();
const port_type ddrB = (port_type) getDdrB();

This is because that global constructor is not called at all. If I call it from main function via

call addrspace(1) void @global_var_init()

it will work.

I use the following commands to compile and download the ll file to the Arduino uno:

llvm-as-9 blink1.ll -o blink1.bc 
llc-9 -filetype=obj blink1.bc 
avr-g++ -mmcu=atmega328p blink1.o -o blink1 
avr-objcopy -O ihex -R .eeprom blink1 blink1.hex 
avrdude -F -V -c arduino -p ATMEGA328P -P /dev/ttyUSB0 -b 115200 -U flash:w:blink1.hex

blink1.ll

; ModuleID = 'blink1.cpp'
source_filename = "blink1.cpp"
target datalayout = "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8"
target triple = "avr"

@portB = dso_local global i8* null, align 1
@ddrB = dso_local global i8* null, align 1
@llvm.global_ctors = appending global [1 x { i32, void () addrspace(1)*, i8* }] [{ i32, void () addrspace(1)*, i8* } { i32 65535, void () addrspace(1)* @global_var_init, i8* null }]


; Function Attrs: noinline
define internal void @global_var_init() addrspace(1) {
  %1 = inttoptr i16 37 to i8*
  store volatile i8* %1, i8** @portB, align 1
  %2 = inttoptr i16 36 to i8*
  store volatile i8* %2, i8** @ddrB, align 1
  ret void
}

; Function Attrs: noinline nounwind optnone
define dso_local void @delay_500ms() addrspace(1) {
  call addrspace(0) void asm sideeffect "ldi  r19, 150 \0A\09ldi  r20, 128 \0A\09ldi  r23, 41 \0A\09L1: \0A\09dec  r20 \0A\09brne L1 \0A\09dec  r19 \0A\09brne L1 \0A\09dec  r23 \0A\09brne L1 \0A\09", ""() #3, !srcloc !2
  ret void
}

; Function Attrs: noinline norecurse nounwind optnone
define dso_local i16 @main() addrspace(1) {
  ; call addrspace(1) void @global_var_init()

  %1 = alloca i16, align 1
  store i16 0, i16* %1, align 1
  %2 = load volatile i8*, i8** @ddrB, align 1
  store i8 32, i8* %2, align 1
  br label %3

3:                                                ; preds = %0, %3
  %4 = load volatile i8*, i8** @portB, align 1
  store i8 32, i8* %4, align 1
  call addrspace(1) void @delay_500ms()
  %5 = load volatile i8*, i8** @portB, align 1
  store i8 0, i8* %5, align 1
  call addrspace(1) void @delay_500ms()
  br label %3
}

!0 = !{i32 1, !"wchar_size", i32 2}
!1 = !{!"clang version 9.0.1-+20210314105943+c1a0a213378a-1~exp1~20210314220516.107 "}
!2 = !{i32 1296, i32 1313, i32 1338, i32 1362, i32 1377, i32 1397, i32 1416, i32 1436, i32 1455, i32 1475, i32 1494}

Is this an LLVM bug or am I doing a mistake?