GCC 6 does not like this:
#define VMW_BIT_MASK(shift) (((1 << (shift - 1)) << 1) - 1)
it produces errors:
/builddir/build/BUILD/open-vm-tools-10.0.0-3000743/lib/include/x86cpuid.h:912:51:
error: result of '-2147483648 << 1' requires 33 bits to represent, but 'int'
only has 32 bits [-Werror=shift-overflow=]
#define VMW_BIT_MASK(shift) (((1 << (shift - 1)) << 1) - 1)
#define VMW_BIT_MASK(shift) (int)~((~0u << (shift - 1)) << 1)
Both shifts are shifts of an 'unsigned int', not anything wider.
Depending on the compiler, this may save time and/or a register
when 'shift' is not a compile-time constant. The final cast
to (int) is only for the purpose of matching the type of the
original expression.
Of course 'shift' must be positive [especially not zero]
and not more than the bit width of an 'int'.
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