Compiler Bugs (use different registers)

[hyungseok]

I discovered that ICC 2021.10.0 sometimes overlooks memory size directives.

I found that ICC incorrectly checks memory size for 11 opcodes when compiling x64 or x86 binaries.

The buggy code contains 11 opcodes.

void bug(int num) {

__asm__(".intel_syntax noprefix\n"

"cldemote ZMMWORD PTR [1]\n"

"clflush ZMMWORD PTR [1]\n"

"clflushopt ZMMWORD PTR [1]\n"

"clwb ZMMWORD PTR [1]\n"

"invlpg ZMMWORD PTR [1]\n"

"prefetch ZMMWORD PTR [1]\n"

"prefetchw ZMMWORD PTR [1]\n"

"prefetcht0 ZMMWORD PTR [1]\n"

"prefetcht1 ZMMWORD PTR [1]\n"

"prefetcht2 ZMMWORD PTR [1]\n"

"prefetchwt1 ZMMWORD PTR [1]\n"

);

}

Compiled Code

bug:

push rbp

mov rbp,rsp

sub rsp,0x10

mov DWORD PTR [rbp-0x10],edi

cldemote BYTE PTR ds:0x1

clflush BYTE PTR ds:0x1

clflushopt BYTE PTR ds:0x1

clwb BYTE PTR ds:0x1

invlpg BYTE PTR ds:0x1

prefetch BYTE PTR ds:0x1

prefetchw BYTE PTR ds:0x1

prefetcht0 BYTE PTR ds:0x1

prefetcht1 BYTE PTR ds:0x1

prefetcht2 BYTE PTR ds:0x1

prefetchwt1 BYTE PTR ds:0x1

leave

ret

You can replay the bug through the godbolt.

https://godbolt.org/z/7Ka8na468

[Alex_Y_Intel]

ICC has been deprecated and removed from our oneAPI Base Toolkit since later versions in 2023. Please migrate to using ICX compiler instead.