register sum weird results

main.asm

    extern  exit

    global _start

    section .data

a:     dd -76, -84, -84, -132
b:     dw 406, 406, 406, 406
    
    section .text
_start:
    movdqa xmm0, [a]
    pmovsxwd xmm2, [b]
    paddq xmm0, xmm2
    ;Expected: 330, 322, 322, 274
    ;Results:  330, 323, 322, 275
    call exit

Makefile

all:
	nasm -f elf64 main.asm
	gcc -g -nostartfiles -no-pie -o main main.o

debug:
	echo "dashboard -output /dev/pts/0\nb _start\nrun >> gdb-log.txt 2>&1\nlayout asm\ndashboard assembly\ndashboard source\ndashboard threads\nset logging file gdb-log.txt\nset logging on\nset trace-commands on\nrecord\n" > gdb-commands.txt
	gdb -x gdb-commands.txt main

clean:
	rm *.o main gdb-commands.txt gdb-log.txt .gdb_history

.PHONY:
	clean asm