`wasm.nx` source

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1// wasm.nx -- NishiLang port of wasm.c (WAT backend).
2//
3// Lowers our SSA IR to WebAssembly Text format.  The core challenge
4// WAT imposes is structured control flow: there are no arbitrary
5// branches, only block/loop/if scopes with break-to-label.  Our IR
6// has free-form CFG edges, so we use the universal block-dispatch
7// pattern (`br_table` driven by a `$target` local) that encodes any
8// CFG at small constant cost.
9//
10// Per-op semantics match wasm.c exactly; every Value gets a $vN
11// local, comparisons extend to i64 after the i32 WASM result, and
12// constants materialize inline as i64.const.
13//
14// Functions are prefixed `wat_` so they don't collide with riscv.nx's
15// asm-side `rv_*` / `emit_*` naming when both libraries are imported
16// into a driver.
17
18import "syscalls.nx"
19import "types.nx"
20import "ir.nx"
21import "outbuf.nx"
22
23// ---- operand emission ----------------------------------------------
24//
25// Push an operand onto the WASM stack.  Constants become literals;
26// everything else reads from its $vN mirror local.
27
28func wat_push_operand(f: *Function, o: *OutBuf, ind: i64, v: i64) -> i64 {
  let val: *Value = val_at(f, v)
  out_indent(o, ind * 2)
  if val.kind == VK_CONST_INT {
      out_str(o, "i64.const ")
      out_i64(o, val.const_int)
      out_char(o, 0x0A)
  } else {
      out_str(o, "local.get $v")
      out_i64(o, v)
      out_char(o, 0x0A)
  }
  return 0
41}
42
43func wat_store_result(o: *OutBuf, ind: i64, v: i64) -> i64 {
  out_indent(o, ind * 2)
  out_str(o, "local.set $v")
  out_i64(o, v)
  out_char(o, 0x0A)
  return 0
49}
50
51// ---- opcode -> WAT mnemonic ----------------------------------------
52
53func wat_binop_mnem(op: i64, o: *OutBuf) -> i64 {
  if op == OP_ADD    { out_str(o, "i64.add");    return 1 }
  if op == OP_SUB    { out_str(o, "i64.sub");    return 1 }
  if op == OP_MUL    { out_str(o, "i64.mul");    return 1 }
  if op == OP_DIV_S  { out_str(o, "i64.div_s");  return 1 }
  if op == OP_REM_S  { out_str(o, "i64.rem_s");  return 1 }
  if op == OP_AND    { out_str(o, "i64.and");    return 1 }
  if op == OP_OR     { out_str(o, "i64.or");     return 1 }
  if op == OP_XOR    { out_str(o, "i64.xor");    return 1 }
  if op == OP_SHL    { out_str(o, "i64.shl");    return 1 }
  if op == OP_SHR_S  { out_str(o, "i64.shr_s");  return 1 }
  if op == OP_SHR_U  { out_str(o, "i64.shr_u");  return 1 }
  return 0
66}
67
68func wat_cmp_mnem(op: i64, o: *OutBuf) -> i64 {
  if op == OP_EQ     { out_str(o, "i64.eq");     return 1 }
  if op == OP_NE     { out_str(o, "i64.ne");     return 1 }
  if op == OP_LT_S   { out_str(o, "i64.lt_s");   return 1 }
  if op == OP_LE_S   { out_str(o, "i64.le_s");   return 1 }
  if op == OP_GT_S   { out_str(o, "i64.gt_s");   return 1 }
  if op == OP_GE_S   { out_str(o, "i64.ge_s");   return 1 }
  return 0
76}
77
78// ---- instruction emission ------------------------------------------
79
80func wat_emit_binop(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  wat_push_operand(f, o, ind, i.op0)
  wat_push_operand(f, o, ind, i.op1)
  out_indent(o, ind * 2)
  wat_binop_mnem(i.op, o)
  out_char(o, 0x0A)
  wat_store_result(o, ind, i.result)
  return 0
88}
89
90func wat_emit_cmp(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  wat_push_operand(f, o, ind, i.op0)
  wat_push_operand(f, o, ind, i.op1)
  out_indent(o, ind * 2)
  wat_cmp_mnem(i.op, o)
  out_char(o, 0x0A)
  // Lift i32 compare result to i64 for uniform storage.
  out_indent(o, ind * 2)
  out_str(o, "i64.extend_i32_u\n")
  wat_store_result(o, ind, i.result)
  return 0
101}
102
103func wat_emit_call(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  let n: i64 = i.n_operands
  if n > 0 { wat_push_operand(f, o, ind, i.op0) }
  if n > 1 { wat_push_operand(f, o, ind, i.op1) }
  if n > 2 { wat_push_operand(f, o, ind, i.op2) }
  if n > 3 { wat_push_operand(f, o, ind, i.op3) }
  out_indent(o, ind * 2)
  out_str(o, "call $")
  if i.callee != (0 as *Function) {
      let name_addr: i64 = i.callee.name_start
      let name: *u8 = name_addr as *u8
      if name != (0 as *u8) {
          out_str(o, name)
      } else {
          out_str(o, "fn_unknown")
      }
  } else {
      out_str(o, "fn_unknown")
  }
  out_char(o, 0x0A)
  wat_store_result(o, ind, i.result)
  return 0
125}
126
127func wat_emit_return(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  if i.n_operands > 0 {
      wat_push_operand(f, o, ind, i.op0)
      out_indent(o, ind * 2)
      out_str(o, "local.set $ret\n")
  }
  out_indent(o, ind * 2)
  out_str(o, "br $exit\n")
  return 0
136}
137
138func wat_emit_branch(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  if i.op == OP_BR {
      out_indent(o, ind * 2)
      out_str(o, "i32.const ")
      out_i64(o, i.op0)
      out_char(o, 0x0A)
      out_indent(o, ind * 2)
      out_str(o, "local.set $target\n")
      out_indent(o, ind * 2)
      out_str(o, "br $dispatch\n")
      return 0
  }
  // br_cond cond ? op1 : op2
  wat_push_operand(f, o, ind, i.op0)
  out_indent(o, ind * 2)
  out_str(o, "i64.const 0\n")
  out_indent(o, ind * 2)
  out_str(o, "i64.ne\n")
  out_indent(o, ind * 2)
  out_str(o, "if\n")
  out_indent(o, (ind + 1) * 2)
  out_str(o, "i32.const ")
  out_i64(o, i.op1)
  out_char(o, 0x0A)
  out_indent(o, (ind + 1) * 2)
  out_str(o, "local.set $target\n")
  out_indent(o, ind * 2)
  out_str(o, "else\n")
  out_indent(o, (ind + 1) * 2)
  out_str(o, "i32.const ")
  out_i64(o, i.op2)
  out_char(o, 0x0A)
  out_indent(o, (ind + 1) * 2)
  out_str(o, "local.set $target\n")
  out_indent(o, ind * 2)
  out_str(o, "end\n")
  out_indent(o, ind * 2)
  out_str(o, "br $dispatch\n")
  return 0
177}
178
179// hardware f32 on the wasm lane (R2 -- the browser lane). The i64 CARRIER (low 32 = IEEE binary32 bits,
180// same layout as the x86 __f32_* lowering) is reinterpreted to a native wasm f32, computed with f32.*,
181// then reinterpreted back to the i64 carrier. So the SAME NishiLang f32 code targets native (SSE) AND browser.
182func wat_emit_f32(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  let op: i64 = i.op
  if op == OP_FCAST_I_TO_F {
      wat_push_operand(f, o, ind, i.op0)
      out_indent(o, ind * 2); out_str(o, "f32.convert_i64_s\n")
      out_indent(o, ind * 2); out_str(o, "i32.reinterpret_f32\n")
      out_indent(o, ind * 2); out_str(o, "i64.extend_i32_u\n")
      wat_store_result(o, ind, i.result)
      return 0
  }
  if op == OP_FCAST_F_TO_I {
      wat_push_operand(f, o, ind, i.op0)
      out_indent(o, ind * 2); out_str(o, "i32.wrap_i64\n")
      out_indent(o, ind * 2); out_str(o, "f32.reinterpret_i32\n")
      out_indent(o, ind * 2); out_str(o, "i64.trunc_f32_s\n")
      wat_store_result(o, ind, i.result)
      return 0
  }
  wat_push_operand(f, o, ind, i.op0)
  out_indent(o, ind * 2); out_str(o, "i32.wrap_i64\n")
  out_indent(o, ind * 2); out_str(o, "f32.reinterpret_i32\n")
  wat_push_operand(f, o, ind, i.op1)
  out_indent(o, ind * 2); out_str(o, "i32.wrap_i64\n")
  out_indent(o, ind * 2); out_str(o, "f32.reinterpret_i32\n")
  out_indent(o, ind * 2)
  if op == OP_FADD { out_str(o, "f32.add\n") }
  if op == OP_FSUB { out_str(o, "f32.sub\n") }
  if op == OP_FMUL { out_str(o, "f32.mul\n") }
  if op == OP_FDIV { out_str(o, "f32.div\n") }
  out_indent(o, ind * 2); out_str(o, "i32.reinterpret_f32\n")
  out_indent(o, ind * 2); out_str(o, "i64.extend_i32_u\n")
  wat_store_result(o, ind, i.result)
  return 0
215}
216
217// Dispatch table for one IR instruction.
218func wat_emit_instr(f: *Function, o: *OutBuf, ind: i64, i: *Instr) -> i64 {
  let op: i64 = i.op
  // Arithmetic / bitwise (1..15 minus 9=NEG which we skip).
  if op == OP_ADD    { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_SUB    { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_MUL    { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_DIV_S  { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_REM_S  { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_AND    { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_OR     { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_XOR    { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_SHL    { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_SHR_S  { wat_emit_binop(f, o, ind, i); return 0 }
  if op == OP_SHR_U  { wat_emit_binop(f, o, ind, i); return 0 }
  // Hardware f32 (browser lane) -- reinterpret carrier <-> native wasm f32.
  if op == OP_FADD         { wat_emit_f32(f, o, ind, i); return 0 }
  if op == OP_FSUB         { wat_emit_f32(f, o, ind, i); return 0 }
  if op == OP_FMUL         { wat_emit_f32(f, o, ind, i); return 0 }
  if op == OP_FDIV         { wat_emit_f32(f, o, ind, i); return 0 }
  if op == OP_FCAST_I_TO_F { wat_emit_f32(f, o, ind, i); return 0 }
  if op == OP_FCAST_F_TO_I { wat_emit_f32(f, o, ind, i); return 0 }
  // Compare.
  if op == OP_EQ     { wat_emit_cmp(f, o, ind, i); return 0 }
  if op == OP_NE     { wat_emit_cmp(f, o, ind, i); return 0 }
  if op == OP_LT_S   { wat_emit_cmp(f, o, ind, i); return 0 }
  if op == OP_LE_S   { wat_emit_cmp(f, o, ind, i); return 0 }
  if op == OP_GT_S   { wat_emit_cmp(f, o, ind, i); return 0 }
  if op == OP_GE_S   { wat_emit_cmp(f, o, ind, i); return 0 }
  // Call / return / branches.
  if op == OP_CALL    { wat_emit_call(f, o, ind, i); return 0 }
  if op == OP_RETURN  { wat_emit_return(f, o, ind, i); return 0 }
  if op == OP_BR      { wat_emit_branch(f, o, ind, i); return 0 }
  if op == OP_BR_COND { wat_emit_branch(f, o, ind, i); return 0 }
  // COPY: push op0 then store result.
  if op == OP_COPY {
      wat_push_operand(f, o, ind, i.op0)
      wat_store_result(o, ind, i.result)
      return 0
  }
  // Unhandled: leave a TODO marker.
  out_indent(o, ind * 2)
  out_str(o, ";; TODO opcode ")
  out_i64(o, op)
  out_char(o, 0x0A)
  return 0
263}
264
265// ---- function emission ---------------------------------------------
266
267func wat_emit_function(f: *Function, o: *OutBuf) -> i64 {
  // Signature.
  out_str(o, "  (func $")
  let name_addr: i64 = f.name_start
  let fn_name: *u8 = name_addr as *u8
  if fn_name != (0 as *u8) {
      out_str(o, fn_name)
  } else {
      out_str(o, "fn")
  }
  // Params: scan values for VAL_PARAM by param_index in order.
  var p: i64 = 0
  while p < f.n_params {
      var v_idx: i64 = 0
      while v_idx < f.n_values {
          let val: *Value = val_at(f, v_idx)
          if val.kind == VK_PARAM {
              if val.param_index == p {
                  out_str(o, " (param $arg")
                  out_i64(o, p)
                  out_str(o, " i64)")
                  v_idx = f.n_values   // break
              }
          }
          v_idx = v_idx + 1
      }
      p = p + 1
  }
  if f.ret_ty != (0 as *Type) {
      if f.ret_ty.kind != 0 {          // TY_VOID = 0
          out_str(o, " (result i64)")
      }
  }
  out_char(o, 0x0A)
301
  // Locals: one i64 per non-constant SSA value.
  var v: i64 = 0
  while v < f.n_values {
      let val2: *Value = val_at(f, v)
      if val2.kind != VK_CONST_INT {
          out_str(o, "    (local $v")
          out_i64(o, v)
          out_str(o, " i64)\n")
      }
      v = v + 1
  }
  out_str(o, "    (local $target i32)\n")
  out_str(o, "    (local $ret i64)\n")
315
  // Copy incoming params into their $vI mirror.
  var vp: i64 = 0
  while vp < f.n_values {
      let val3: *Value = val_at(f, vp)
      if val3.kind == VK_PARAM {
          out_str(o, "    local.get $arg")
          out_i64(o, val3.param_index)
          out_char(o, 0x0A)
          out_str(o, "    local.set $v")
          out_i64(o, vp)
          out_char(o, 0x0A)
      }
      vp = vp + 1
  }
330
  // Initial dispatch target = 0 (entry block).
  out_str(o, "    i32.const 0\n")
  out_str(o, "    local.set $target\n")
334
  // Open block-dispatch scaffolding.  (block $exit / (loop $dispatch
  // / (block $bb_default / nested (block $bbN) ... (block $bb0) ...
  let N: i64 = f.n_blocks
  out_str(o, "    (block $exit\n")
  out_str(o, "      (loop $dispatch\n")
  out_str(o, "        (block $bb_default\n")
  var bi: i64 = N - 1
  while bi >= 0 {
      let ind_lvl: i64 = 4 + (N - 1 - bi)
      out_indent(o, ind_lvl * 2)
      out_str(o, "(block $bb")
      out_i64(o, bi)
      out_char(o, 0x0A)
      bi = bi - 1
  }
350
  // br_table at deepest indent.
  let deepest: i64 = 4 + N
  out_indent(o, deepest * 2)
  out_str(o, "br_table")
  var bt: i64 = 0
  while bt < N {
      out_str(o, " $bb")
      out_i64(o, bt)
      bt = bt + 1
  }
  out_str(o, " $bb_default\n")
  out_indent(o, deepest * 2)
  out_str(o, "local.get $target\n")
364
  // Close each bbB, emit its body at (4+N-B-1) indent.
  var b: i64 = 0
  while b < N {
      let close_ind: i64 = 4 + N - b - 1
      out_indent(o, close_ind * 2)
      out_str(o, ")\n")
      let bb: *BasicBlock = block_at(f, b)
      var inst: *Instr = bb.head
      while inst != (0 as *Instr) {
          wat_emit_instr(f, o, close_ind, inst)
          inst = inst.next
      }
      b = b + 1
  }
379
  // Close bb_default + body (unreachable).
  out_str(o, "        )\n")
  out_str(o, "        unreachable\n")
  out_str(o, "      )\n")           // close loop $dispatch
  out_str(o, "    )\n")             // close block $exit
385
  // Return the stashed ret value.
  if f.ret_ty != (0 as *Type) {
      if f.ret_ty.kind != 0 {
          out_str(o, "    local.get $ret\n")
      }
  }
  out_str(o, "  )\n")               // close (func
393
  // Export under the function's own name.
  if fn_name != (0 as *u8) {
      out_str(o, "  (export \"")
      out_str(o, fn_name)
      out_str(o, "\" (func $")
      out_str(o, fn_name)
      out_str(o, "))\n")
  }
  return 0
403}
404
405// ---- module emission -----------------------------------------------
406
407func wat_emit_module(m: *Module, o: *OutBuf) -> i64 {
  out_str(o, ";; Auto-generated by nxc2.nx WASM (WAT) backend.\n")
  out_str(o, ";; Module: ")
  if m.name != (0 as *u8) { out_str(o, m.name) }
  out_char(o, 0x0A)
  out_str(o, "(module\n")
  var i: i64 = 0
  while i < m.n_functions {
      let fn_base: i64 = m.functions as i64
      let f: *Function = (fn_base + i * 176) as *Function
      wat_emit_function(f, o)
      i = i + 1
  }
  out_str(o, ")\n")
  return 0
422}
423
424// Library only; self-test lives in wasm_test.nx.
wasm.nx source

`wasm.nx` source
