Sun Microsystems UltraSPARC-I User Manual page 301

UltraSPARC User's Manual
Instructions that read the result of a
or the following group. For example:
MOVcc %xcc, 0, i6
LDX [i6+i1], i8
Instructions that read the result of an
cannot be in the same group or in the two following groups.
pendent on earlier
enced. For example:
FCMPLE32 f2, f4, i6
LDX [i6+i1], i8
In some cases, UltraSPARC prematurely dispatches an instruction that uses the
result of an
FCMP{LE,NE,GT,EQ}{16,32}
Stage and refetches it. This effectively inserts nine bubbles into the pipe. To avoid
this, software should explicitly force the use instruction to be in the third group or
later after the
FCMP{LE,NE,GT,EQ}{16,32}
,
MULX {U,S}MUL{cc}
two groups following an FC
FCMPLE32 f2, f4, i6
MUL i8,i7,i9
cannot be in the same group or in the group following an IEU instruction,
FMOVr
even if it does not reference the result of the IEU instruction. It cannot be in the
same group or the next two groups following an FC
example:
ADD i1, i2, i6
FMOVr i5,i7
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or
MOVcc
G E C N
1
G E
FCMP{LE,NE,GT,EQ}{16,32}
instructions, regardless of the actual registers refer-
FCMP
G E C N
1
G
; it then cancels the instruction in the W
.
, , ,
MULScc {U,S}DIV{X} {U,S}DIVcc,
MP{LE,NE,GT,EQ}{16,32}
G E C N
1
G
G E C N
1
G E
cannot be in the same group
MOVr
N N W
2 3
C N N N W
1 2 3
(including stores)
is treated as de-
STD
N N W
2 3
E C N N N W
1 2 3
and cannot be in the
STD
. For example:
N N W
2 3
E C N N N W
1 2 3
MP{LE,NE,GT,EQ}{16,32}
N N W
2 3
C N N N W
1 2 3
. For