w6c: delete unwired backend pass seams

cmd/w6c/CLAUDE.md

@@ -2,5 +2,5 @@ w6c — amd64 compiler. Reads `.ww`, writes Plan 9 amd64 assembly (`.s`).
 
 - Plan 9 C style: tabs, K&R, short names. Mirror `ref/plan9front/sys/src/cmd/8c/` and `ref/plan9front/sys/src/cmd/cc/`. Do not invent new data shapes — reuse `Prog`/`Adr`/`Node`/`Sym`/`Type` conventions.
 - Frontend (lex, parse, check) lives in `../wcc/` and links as `libwcc.a`. This directory owns codegen only.
-- `gc.h` is the per-target header (Plan 9 cc convention). `cgen.c` walks the AST into `Prog` list; `txt.c` prints it. `peep.c` is peephole. `reg.c` is the register allocator. `swt.c` is switch lowering.
+- `gc.h` is the per-target header (Plan 9 cc convention). `cgen.c` performs the current AST lowering into a `Prog` list, including switch lowering; `txt.c` emits the assembler text. There is no peephole or register-allocation pass yet.
 - The text output must be readable by `w6a` (the amd64 assembler under `../w6a/`). When in doubt about syntax, run `w6a` on the output.

cmd/w6c/cgen.c

@@ -17683,6 +17683,3 @@ cg_file(Cg *c, FILE *out, Node *file)
 	emit_defs(c, out, file);
 	emit_lets(c, out, file);
 }
-
-void	peephole(Cg *c) { (void)c; }
-void	regalloc_init(Cg *c) { (void)c; }

cmd/w6c/gc.h

@@ -73,8 +73,4 @@ void	txt_emit(FILE*, Prog *head);
 /* wwi.c — non-zero return: check_exported_type rejected a dangling export. */
 int	wwi_emit(Checker *c, FILE *of, Node *file);
 
-/* swt.c, peep.c, reg.c — placeholders for now */
-void	peephole(Cg*);
-void	regalloc_init(Cg*);
-
 #endif

cmd/w6c/peep.c

@@ -1,8 +0,0 @@
-/*
- * Currently a no-op; reserved for the kind of cleanup Plan 9 6c does
- * (folding adjacent moves, removing redundant compares). Wire in
- * `peephole(c)` from cgen.c after the main walk.
- */
-#include "gc.h"
-
-void	peep_run(Cg *c) { (void)c; }

cmd/w6c/reg.c

@@ -1,9 +0,0 @@
-/*
- * The current cgen pins everything to AX with BX as a scratch
- * top-of-stack — no real allocation. This file is the seam where a
- * linear-scan or graph-colouring pass would land later; today it's
- * empty.
- */
-#include "gc.h"
-
-void	reg_run(Cg *c) { (void)c; }

cmd/w6c/swt.c

@@ -1,8 +0,0 @@
-/*
- * Stub for now: cgen falls through to a no-op for N_SWITCH. When we
- * add a real lowering, it will live here, mirroring Plan 9 6c's
- * pswt.c.
- */
-#include "gc.h"
-
-void	swt_lower(Cg *c, Node *n) { (void)c; (void)n; }

cmd/w6c/txt.c

@@ -1,6 +1,6 @@
 /*
  * Format we emit (and that w6a expects):
- *   TEXT name<framesize>
+ *   TEXT name,$framesize
  *       MOVQ $1, AX
  *       MOVQ AX, name(SB)        ; extern symbol
  *       MOVQ off(BP), AX         ; local