--- firefox-66.0.5/js/src/jit/x86-shared/Assembler-x86-shared.cpp.orig 2019-05-11 23:41:10.894664764 +0100 +++ firefox-66.0.5/js/src/jit/x86-shared/Assembler-x86-shared.cpp 2019-05-12 11:39:51.269766814 +0100 @@ -328,12 +328,14 @@ avxPresent = (xcr0EAX & xcr0SSEBit) && (xcr0EAX & xcr0AVXBit); } + if (maxSSEVersion >= SSE2) { // CMOV instruction are supposed to be supported by all CPU which have SSE2 // enabled. While this might be true, this is not guaranteed by any // documentation, nor AMD, nor Intel. static constexpr int CMOVBit = 1 << 15; MOZ_RELEASE_ASSERT(flagsEdx & CMOVBit, "CMOVcc instruction is not recognized by this CPU."); + } static constexpr int POPCNTBit = 1 << 23; popcntPresent = (flagsEcx & POPCNTBit);