Sun Microsystems UltraSPARC-I User Manual page 313

UltraSPARC User's Manual
Floating-point stores other than
graphics instruction other than
ample:
FADDs f2, f5, f6
STF f6, [address]
Floating-point stores of the result of an
dependent floating-point instruction.
cannot be dispatched in the two groups following a floating-point or
ST(X)FSR
graphics instruction that references the floating-point registers. For example:
FMULd
STFSR
To simplify critical timing paths, floating-point operations are usually stalled in
the G Stage until earlier floating-point operations with a different precision com-
plete, regardless of data dependency. This behavior is described more precisely in
the following two rules. Floating-point loads and stores are independent of these
mixed precision rules.
1. A floating-point or graphics instruction that follows an
of different precision break the group, even if there is no data dependency.
For example:
FMOVs
FMULd
2. A floating-point or graphics instruction following an operation other than
,
FMOV FABS
N Stage of the earlier operation, even if there is no data dependency. For
2
example:
FADDs f2, f5, f0
FMULd f2, f2, f2
As an exception to the previous rule,
er operation of different precision, but are stalled until the N
operation otherwise.
Sun Microelectronics
298
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
can store the result of a floating-point or
ST{X}FSR
or
FDIV FSQRT
G E C N
G E C N
FDIV
G E C N N N
1 2 3
G E C
G E C N N
1
G E C N
, , , of different precision is stalled until the
FNEG FDIV FSQRT
G E
FDIV
and be in the same group. For ex-
N N W
1 2 3
N N W
1 2 3
or are treated the same as a
FSQRT
W
N N N
1 2 3
FMOV
N W
2 3
N N W
1 2 3
C N N N W
1 2 3
G E C N
1
or can be grouped with an old-
FSQRT
Stage of the earlier
2
, ,
FABS FNEG
N
2