Appeal No. 1995-3690 Page 7
Application No. 08/000,342
A precise interrupt is a mechanism to report traps (i.e.
errors) in instructions in which:
a) the program counter points to the
instruction which caused the trap; and
b) all instructions that preceded the
trapping instruction in the program have
executed without a trap and have correctly
modified the state; and
c) all instructions succeeding the
trapping instruction are unexecuted and
have not modified the state [specification
at pages 5 and 6].
The specification discloses a method for implementing
speculative instructions in which all speculative2
instructions from the same basic block have the identical tag
(specification at page 18). The tagged instructions are
issued speculatively and the results
are stored in a shadow buffer. A checkpoint instruction is
inserted before the “origin point” of the tagged 3
instructions. This checkpoint instruction takes the
corresponding tag as an argument and reports any tag that has
2An instruction is considered speculative if it is
issued before unresolved previous branches.
3An origin point of a tagged instructions is the point
in the program where the tagged instruction would have issued
had it not been tagged.
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Next
Last modified: November 3, 2007