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int now uses intelligent calls

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ceriel 1990-06-21 13:17:50 +00:00
parent 4355b05597
commit f218a430f6
1 changed files with 4 additions and 10 deletions
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doc/int/txt2
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@ -529,7 +529,7 @@ types are described in [1]. Each opcode in the text segment identifies an
instruction with a particular operand type; these relations are described in instruction with a particular operand type; these relations are described in
computer-readable format in a file in the EM tree, \fIip_spec.t\fP. computer-readable format in a file in the EM tree, \fIip_spec.t\fP.
.PP .PP
The interpreter uses a variant of the second method. Several other approaches The interpreter uses the third method. Several other approaches
can be designed, with increasing efficiency and equally increasing complexity. can be designed, with increasing efficiency and equally increasing complexity.
They are briefly treated below. They are briefly treated below.
.NH 3 .NH 3
@ -557,20 +557,14 @@ decoding is immediate, and no dispatch table is needed. Generation of the
of routine names or a generated switch statement is used to map the opcode onto of routine names or a generated switch statement is used to map the opcode onto
the correct routine. The switch approach has the advantage that parameters can the correct routine. The switch approach has the advantage that parameters can
be passed to the routines. be passed to the routines.
.LP
The interpreter uses a variant of the switch statement scheme. Numerical
information that can be deduced from the opcode is passed as parameters to the
routine; this includes the argument of minis, the high order byte of shorties,
and the fact that the result is to be multiplied by the word size. This
reduces the number of required routines to 338.
.NH 3 .NH 3
Intelligent Calls. Intelligent Calls, Method 3.
.PP .PP
The call in the switch statement does full operand construction, and the The call in the switch statement does full operand construction, and the
resulting operand is passed to the routine. This reduces the number of resulting operand is passed to the routine. This reduces the number of
routines to 133, the number of EM instructions. Generation of the switch routines to 133, the number of EM instructions. Generation of the switch
statement from ip_spec.t will be complicated, but the routine space will be statement from ip_spec.t is more complicated, but the routine space is
much cleaner. This will not give any speed-up since the same actions are still much cleaner. This does not give any speed-up since the same actions are still
required; they are just performed in a different place. required; they are just performed in a different place.
.NH 3 .NH 3
Static Evaluation. Static Evaluation.