pdp11-c2

Ritchie cc's peephole optimizer. Reads c1's assembler output, rewrites redundant sequences, and emits smaller equivalent assembler; cc -O runs it.

pdp11-c2 in.s out.s

• Byte-for-byte faithful. The library built with cc -O reproduces native 2.9 libc members exactly — the optimizer's rewrites match the original's, verified across whole archives in the oracle sweeps.
• Identical in both source trees: 2.8 and 2.9 shipped the same c2; either copy is this one.

Documentation

• Design — the optional peephole optimizer and the transforms it applies.
• User guide — what -O turns on and how to run it.
• docs/porting.md — the porting guide.

Build and test

make          # builds ../../bin/pdp11-c2
make check    # covered by tests/cc/optimizer.sh and the [-O] re-run
              # of the correctness suite at the repo root