SYSNOPIS
copt file ...DESCRIPTION
copt is a general-purpose peephole optimizer. It reads code from its standard input and writes an improved version to its standard output. copy reads the named files for its optimizations, which are encoded as follows:
<pattern for input line 1>
<pattern for input line 2>
...
<pattern for input line n>
=
<pattern for output line 1>
<pattern for output line 2>
...
<pattern for output line m>
<blank line>
Pattern matching uses literal string comparison, with one
exception: ``%%'' matches the ``%'' character, and ``%''
followed by a digit matches everything up to the next
occurrence of the next pattern character, though all
occurrences of %n must denote the same string. For example,
the pattern ``%1=%1.'' matches exactly those strings
that begin with a string X, followed by a ``='' (the
first), followed by a second occurrence of X, followed by
a period. In this way, the input/output pattern
mov $%1,r%2
mov *r%2,r%2
=
mov %1,r%2
commands copt to replace runs like
mov $_a,r3
mov *r3,r3
with
mov _a,r3
Note that a tab or newline can terminate a %n variable.
copt compares each run of input patterns with the current input instruction and its predecessors. If no match is found, it advances to the next input instruction and tries again. Otherwise, it replaces the input instructions with the corresponding output patterns, pattern variables instantiated,and resumes its search with the first instruction of the replacement. copt matches input patterns in reverse order to cascade optimizations without backing up.