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TCG: QEMU incorrectly raises exception on SSE4.2 CRC32 instruction
If I run FreeBSD on QEMU 5.2 with TCG acceleration -cpu Nehalem, I get a FPU exception when executing crc32 (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253617). This is not a problem with the default CPU (or KVM) since that does not support SSE 4.2.
Attaching GDB shows this is triggered in target/i386/tcg/translate.c:3067
/* simple MMX/SSE operation */
if (s->flags & HF_TS_MASK) {
gen_exception(s, EXCP07_PREX, pc_start - s->cs_base);
return;
}
However, according to https://software.intel.com/sites/default/files/m/8/b/8/D9156103.pdf, page 61 the CRC32 instruction works no matter what the value of the TS bit.
The code sequence in question is:
0xffffffff8105a4de <+126>: f2 48 0f 38 f1 de crc32q %rsi,%rbx
0xffffffff8105a4e4 <+132>: f2 48 0f 38 f1 ca crc32q %rdx,%rcx.
This should work even with the FPU disabled.
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