code wiki / (root) / nx_ir_validate.nx
`nx_ir_validate.nx` source

↩ module page · 271 lines · 10488 B
1// ir_validate.nx -- structural invariants on the in-memory IR.
2//
3// Mirrors what nxc2/ir_validate.c does for the C anchor, ported to
4// run inside nxc.elf so the sovereign pipeline can self-check.
5// Catches the class of bug that bit us 2026-04-25:
6//   * BR / BR_COND op_X references a block id past f.n_blocks
7//     (the dangling-label landmine).
8//   * BR / BR_COND op_X disagrees with bb.succ0 / bb.succ1
9//     (the stale-pointer landmine).
10//   * A block listed in f.blocks has a different .id than its
11//     position (the compaction-skew landmine).
12//
13// Designed to run AFTER each opt pass.  When an invariant breaks,
14// the validator prints {function name, pass label, block id,
15// invariant code, instr op} to stderr and returns the count of
16// violations.  Caller decides whether to abort or continue.
17//
18// Design rule: validator reads f only -- no writes.  Safe to
19// invoke between any two passes without altering pipeline behavior.
20
21// nx_safety_envelope:
22//   intended_use:       AUTO_APPLIED -- primitive-specific tuning queued
23//   sil_target:         SIL1
24//   evidence:           [bulk_applied_2026-05-16, see-file-comment-for-detail]
25//   verdict:            NOT_YET_EVALUATED
26
27import "nx_types.nx"
28import "nx_syscalls.nx"
29import "nx_ir.nx"
30
31// ----- one-char + decimal helpers (local; no log.nx dep) -----
32
33func iv_putc(c: i64) -> i64 {
  let buf: *u8 = sys_mmap(8)
  buf[0] = c
  sys_write(2, buf, 1)
  return 0
38}
39
40func iv_puts(s: *u8) -> i64 {
  var n: i64 = 0
  while s[n] != 0 { n = n + 1 }
  sys_write(2, s, n)
  return 0
45}
46
47func iv_putd(v: i64) -> i64 {
  let buf: *u8 = sys_mmap(32)
  var n: i64 = v
  if n < 0 {
      iv_putc(0x2D)   // '-'
      n = 0 - n
  }
  var k: i64 = 0
  if n == 0 { buf[k] = 0x30; k = 1 }
  while n > 0 {
      buf[k] = 0x30 + (n - (n / 10) * 10)
      n = n / 10
      k = k + 1
  }
  var j: i64 = k - 1
  while j >= 0 {
      sys_write(2, (((buf as i64) + j) as *u8), 1)
      j = j - 1
  }
  return 0
67}
68
69// Print one violation header: "ir_validate[<pass>] <fn>: ".  fn name
70// is read from f.name_start (stored as *u8 pointer per ir.nx
71// convention).
72func iv_violation(f: *Function, pass_label: *u8) -> i64 {
  iv_puts("ir_validate[" as *u8)
  iv_puts(pass_label)
  iv_puts("] " as *u8)
  let fname: *u8 = f.name_start as *u8
  var ni: i64 = 0
  while fname[ni] != 0 { ni = ni + 1 }
  sys_write(2, fname, ni)
  iv_puts(": " as *u8)
  return 0
82}
83
84// ----- the validator -----
85
86// Returns the number of violations found.  Caller picks abort vs
87// continue.  Pass `pass_label` is a short c-string identifying which
88// opt pass just ran (e.g. "post-sweep", "post-sccp", "post-parse").
89func ir_validate_function(f: *Function, pass_label: *u8) -> i64 {
  var violations: i64 = 0
  let n: i64 = f.n_blocks
  if n == 0 { return 0 }
93
  var bi: i64 = 0
  while bi < n {
      let bb: *BasicBlock = block_at(f, bi)
97
      // V1: block at slot bi must have .id == bi (compaction
      // invariant -- post-SWEEP2 should hold).
      if bb.id != bi {
          iv_violation(f, pass_label)
          iv_puts("V1 bb at slot " as *u8); iv_putd(bi)
          iv_puts(" has .id=" as *u8); iv_putd(bb.id)
          iv_putc(0x0A)
          violations = violations + 1
      }
107
      // V2 + V3: walk this block's instructions; any BR/BR_COND
      // operand id must be in range, AND any non-zero succ pointer
      // must match the BR/BR_COND it corresponds to.
      var inst: *Instr = bb.head
      var saw_br: i64 = 0
      var saw_br_cond: i64 = 0
      var br_target: i64 = -1
      var br_cond_t: i64 = -1
      var br_cond_f: i64 = -1
      while inst != (0 as *Instr) {
          if inst.op == OP_BR {
              if saw_br == 0 { br_target = inst.op0 }
              saw_br = saw_br + 1
              if inst.op0 < 0 {
                  iv_violation(f, pass_label)
                  iv_puts("V2 bb" as *u8); iv_putd(bi)
                  iv_puts(" OP_BR target=" as *u8); iv_putd(inst.op0)
                  iv_puts(" (negative)" as *u8); iv_putc(0x0A)
                  violations = violations + 1
              }
              if inst.op0 >= n {
                  iv_violation(f, pass_label)
                  iv_puts("V2 bb" as *u8); iv_putd(bi)
                  iv_puts(" OP_BR target=" as *u8); iv_putd(inst.op0)
                  iv_puts(" out of range (n_blocks=" as *u8); iv_putd(n)
                  iv_puts(")" as *u8); iv_putc(0x0A)
                  violations = violations + 1
              }
          }
          if inst.op == OP_BR_COND {
              if saw_br_cond == 0 {
                  br_cond_t = inst.op1
                  br_cond_f = inst.op2
              }
              saw_br_cond = saw_br_cond + 1
              if inst.op1 < 0 {
                  iv_violation(f, pass_label)
                  iv_puts("V2 bb" as *u8); iv_putd(bi)
                  iv_puts(" OP_BR_COND on_true=" as *u8); iv_putd(inst.op1)
                  iv_puts(" (negative)" as *u8); iv_putc(0x0A)
                  violations = violations + 1
              }
              if inst.op1 >= n {
                  iv_violation(f, pass_label)
                  iv_puts("V2 bb" as *u8); iv_putd(bi)
                  iv_puts(" OP_BR_COND on_true=" as *u8); iv_putd(inst.op1)
                  iv_puts(" out of range (n_blocks=" as *u8); iv_putd(n)
                  iv_puts(")" as *u8); iv_putc(0x0A)
                  violations = violations + 1
              }
              if inst.op2 < 0 {
                  iv_violation(f, pass_label)
                  iv_puts("V2 bb" as *u8); iv_putd(bi)
                  iv_puts(" OP_BR_COND on_false=" as *u8); iv_putd(inst.op2)
                  iv_puts(" (negative)" as *u8); iv_putc(0x0A)
                  violations = violations + 1
              }
              if inst.op2 >= n {
                  iv_violation(f, pass_label)
                  iv_puts("V2 bb" as *u8); iv_putd(bi)
                  iv_puts(" OP_BR_COND on_false=" as *u8); iv_putd(inst.op2)
                  iv_puts(" out of range (n_blocks=" as *u8); iv_putd(n)
                  iv_puts(")" as *u8); iv_putc(0x0A)
                  violations = violations + 1
              }
          }
          inst = inst.next
      }
176
      // V3: succ pointer must agree with the BR/BR_COND op id (if
      // either side is set).  Tonight's bug: succ stale, op fresh.
      // We don't insist succ is non-null -- some passes legitimately
      // clear it -- but if it IS non-null it must agree.
      if saw_br_cond > 0 {
          if bb.succ0 != (0 as *BasicBlock) {
              if bb.succ0.id != br_cond_t {
                  if br_cond_t >= 0 {
                      if br_cond_t < n {
                          iv_violation(f, pass_label)
                          iv_puts("V3 bb" as *u8); iv_putd(bi)
                          iv_puts(" succ0.id=" as *u8); iv_putd(bb.succ0.id)
                          iv_puts(" but BR_COND on_true=" as *u8); iv_putd(br_cond_t)
                          iv_putc(0x0A)
                          violations = violations + 1
                      }
                  }
              }
          }
          if bb.succ1 != (0 as *BasicBlock) {
              if bb.succ1.id != br_cond_f {
                  if br_cond_f >= 0 {
                      if br_cond_f < n {
                          iv_violation(f, pass_label)
                          iv_puts("V3 bb" as *u8); iv_putd(bi)
                          iv_puts(" succ1.id=" as *u8); iv_putd(bb.succ1.id)
                          iv_puts(" but BR_COND on_false=" as *u8); iv_putd(br_cond_f)
                          iv_putc(0x0A)
                          violations = violations + 1
                      }
                  }
              }
          }
      }
      if saw_br > 0 {
          if saw_br_cond == 0 {
              if bb.succ0 != (0 as *BasicBlock) {
                  if bb.succ0.id != br_target {
                      if br_target >= 0 {
                          if br_target < n {
                              iv_violation(f, pass_label)
                              iv_puts("V3 bb" as *u8); iv_putd(bi)
                              iv_puts(" succ0.id=" as *u8); iv_putd(bb.succ0.id)
                              iv_puts(" but BR target=" as *u8); iv_putd(br_target)
                              iv_putc(0x0A)
                              violations = violations + 1
                          }
                      }
                  }
              }
          }
      }
229
      // V4: every block must END in a terminator (OP_RETURN / OP_BR /
      // OP_BR_COND / OP_TAIL_CALL).  Backends emit blocks in creation
      // order and never use intentional fallthrough; an open block
      // falls through into whatever block was created next, which is
      // NOT its CFG successor.  Caught live 2026-06-09: parse_function
      // left the final loop-exit block of nx_ttt_evaluate open, so the
      // board-full DRAW store fell through into the cell-empty ONGOING
      // store -- draw detection silently clobbered on x86 AND RISC-V.
      let tail: *Instr = bb.tail
      var v4_terminated: i64 = 0
      if tail != (0 as *Instr) {
          if tail.op == OP_RETURN    { v4_terminated = 1 }
          if tail.op == OP_BR        { v4_terminated = 1 }
          if tail.op == OP_BR_COND   { v4_terminated = 1 }
          if tail.op == OP_TAIL_CALL { v4_terminated = 1 }
      }
      if v4_terminated == 0 {
          iv_violation(f, pass_label)
          iv_puts("V4 bb" as *u8); iv_putd(bi)
          iv_puts(" has no terminator (falls through to wrong block)" as *u8)
          iv_putc(0x0A)
          violations = violations + 1
      }
253
      bi = bi + 1
  }
256
  return violations
258}
259
260// Validate every function in a Module.  Returns total violations.
261func ir_validate_module(m: *Module, pass_label: *u8) -> i64 {
  var total: i64 = 0
  var i: i64 = 0
  while i < m.n_functions {
      let base: i64 = m.functions as i64
      let f: *Function = (base + i * 176) as *Function
      total = total + ir_validate_function(f, pass_label)
      i = i + 1
  }
  return total
271}
nx_ir_validate.nx source

`nx_ir_validate.nx` source
