pdp11-c1

Ritchie cc pass 2: the PDP-11 code generator. Reads c0's intermediate stream and emits 2BSD assembler for as.

pdp11-c1 tmp1 tmp2 out.s [-V]

• The codegen table is authored, not hand-written. table.s is the authentic template source; the build runs it through cvopt (the 2BSD table compiler) and then mktab (a host helper) so the table compiles into the host binary instead of being assembled for the PDP-11.
• Codegen-correctness fixes over the 2.8 port: geti() sign-extends to 16 bits (negative switch cases had degraded to compare chains), long-constant halves are masked before the int-fold test (-1L now folds), and negative auto offsets print as 16-bit octal, matching the native listings.
• DEC floating point, not host floating point. FP constants convert through softfp.c into exact 56-bit D-format — the last byte matches the 1981 compiler.

Documentation

• Design — the second pass -- code generation from the c0 intermediate.
• User guide — invocation and the temp-file protocol.
• docs/porting.md — the porting guide, including the cvopt/mktab table pipeline.

Build and test

make          # builds ../../bin/pdp11-c1 (regenerates table.c)
make check    # covered by tests/c1/codegen.sh and the oracle corpus
              # (oracle/run.sh: our c1 vs the 1981 c1 under apsim)