# V3 step 2 — REAL lowering: the scalar story is complete (done 2026-09-19)

With step 1.9's statements + this section, every scalar kind lowers:
INTEGER/CARDINAL-family, BOOLEAN, CHAR, REAL/LONGREAL (widened to
`d`), with conversions, comparisons and full control flow.
Suite 30/30 (14 run + 16 reject), LL(1)-clean, zero regressions.

## Backend (`QbeGen`)

- `d_` immediates (`NormReal`); `IsImm` accepts them; `NegFold`
  folds `d_` literals (Test2 recipe).
- `DeclVar`: `data $x = { d 0 }` for ClReal. `DeclConst`: zero
  reals as `d 0` (textual `IsZeroReal`, incl. `-0.0`); non-zero
  REALs as `d 0` + a recorded runtime `=d copy` flushed at
  `BeginBody` (this qbe rejects `d 1.5` in `data` — same limit
  Test2 hit, same workaround).
- Threaded `isReal` through LoadVar (`loadd`) / StoreVar (`stored`)
  / Op3 (`=d`); `Cmp` gains ceqd/cned/cltd/cled/cgtd/cged;
  `NegQ` via `sub d_0.0`; new `ConvIR` (`swtof`) for
  INTEGER→REAL assignment widening.

## Grammar (isReal threading, Test1 type rules)

- Real literals fold (`NormReal`, no more 230); `/` added to MulOp
  (OpSlash → `div`, Test2 parity: also defined on integers as
  truncating division — documented, matches the lenient family).
- `VAR x: REAL` accepted; loads/stores carry the class flag in
  Design (var/param/const), SimExpr/Term (arith + unary minus),
  Expr (comparisons; flag read before the type becomes BOOLEAN).
- Conversions ONLY via assignment (`r := 3` → swtof); mixed
  arithmetic and mixed comparisons stay 211/213; REAL→INTEGER
  is 210. No implicit anything else.

## Tests

`t_real` → 31 (zero + flushed CONSTs, conversion, all six real
comparisons, `/`, real unary-minus temps, int/real branches) with
hand-checked `.ssa` (flush block, swtof, cgtd all present);
`t_bad_mixed` (`i := r`) → 210.

## Honest leftovers (scalar)

- CHAR arithmetic is 211; enum literals don't lower (use is 230);
  enum/char subrange bounds are integer-only.
- `LONGINT`/`LONGREAL` are aliases (true quads = later step).
- `5 / 2` on integers truncates (Test2 parity, not Wirth `/`).
- Division by zero traps via QBE/SIGFPE (no language Trap yet —
  arrives with `runtime/syslib/Trap`).

Next: step 3 composites (ARRAY/RECORD/SET/POINTER + the locked
length-prefixed layout + WITH + IN).