ICC/ICX compiler bugs (change registgers)

[hyungseok]

I found that ICX 2024.0.0 and ICC 2021.10.0 change registers without any alarm messages.

This error has been identified in 3 opcodes (lar, movmskpd, pmovmskb) in ICX and in 6 opcodes (lar, mov, movmskpd, pmovmskb, sldt, str) in ICC.

Buggy Code

void bug(int num) {

__asm__(".intel_syntax noprefix\n"

"lar R11, R8W\n"

"mov R10, GS\n"

"movmskpd R9, XMM0\n"

"pmovmskb R10, MM2\n"

"sldt R15\n"

"str R8\n"

);

}

Compiled Code (ICX 2024.0.0)

You can reproduce the result through the godbolt: 

https://godbolt.org/z/1Md7Ysv73 

bug:

push rbp

mov rbp,rsp

mov DWORD PTR [rbp-0x4],edi

lar r11,r8

mov r10,gs

movmskpd r9d,xmm0

pmovmskb r10d,mm2

sldt r15

str r8

pop rbp

ret

Compiled Code (ICC 2021.10.0)

You can reproduce the result through the godbolt: 

https://godbolt.org/z/5os84qzWh 

bug:

push rbp

mov rbp,rsp

sub rsp,0x10

mov DWORD PTR [rbp-0x10],edi

lar r11,r8

mov r10d,gs

movmskpd r9d,xmm0

pmovmskb r10d,mm2

sldt r15d

str r8d

leave

ret

[Alex_Y_Intel]

I've escalated your problem to our internal team. Please note that ICC has been deprecated and removed from our oneAPI Base Toolkit since later versions in 2023. Please migrate to using ICX compiler instead. 

[Alex_Y_Intel]

This is not a defect. All compilers behave the same https://godbolt.org/z/TEqd7qYh9