On 2018-08-03 11:27, Houder wrote:
I discovered a difference in behaviour between the x87 FPU and SSE.
When an exception is masked, a "default action" is carried out when
an exception occurs. At the same time the associated status flag is
set.
(the manual speaks about a "reasonable" default action, an action
that is "sufficient" most of the times)
When the exception is enabled again, SSE is not bothered. However
the next _FPU_ statement will notice the status flag set, and will
set the "Exception Summary Bit" (in the FPU's status register).
To clarify:
SSE has a "control and status register". The x87 FPU has a control
register and a status register.
Flags are only set in x87 FPU's status register when FPU statements
are executed.
(the FPU is not "interested" in SSE's control and status register)
Henri
