Chapter 25: add separate compilation and simplify SSA construction

Introduce Chapter 25 with separately compiled Simple modules, serialized IR,
cross-compilation-unit linking, and native system-library integration.  This
also completes a broad parser and type-system cleanup needed to make graph
construction independent of incomplete parse-time type information.

Separate compilation and linking

- Add compilation-unit Start/Stop nodes and track functions, classes, aliases,
  and global indices across compilation-unit boundaries.
- Serialize canonical types and ideal graph nodes into ELF objects, including
  dependency metadata, relocations, global/local bitset remapping, and dense
  memory-alias information.
- Load dependent objects on demand, recursively resolve source and object
  paths, relink calls and function pointers, and preserve external C symbols.
- Distinguish the post-optimization ownership hook from unknown callers so
  private call graphs can remain precise while public functions remain
  externally callable.
- Add command-line and build support for compiling modules and the reusable
  `sys` object library.

Parser, constructors, and SSA

- Replace inline constructor expansion with a hidden default `<init>` followed
  by an explicit user constructor declared as `new Type = { ... }`.
- Keep the default constructor private, pass private object memory through
  constructor calls, and require user constructors to initialize non-default
  fields before the object escapes.
- Track possibly-uninitialized fields in parser `Var` state and diagnose early
  reads without encoding parser-only constraints in Load and Store nodes.
- Make ordinary parser memory bulk and recover precise alias slices in the
  optimizer using `MemMerge`, `MemPhi`, and `BulkMemPhi` nodes.
- Remove parser-supplied type constraints from Loads and ordinary Phis, defer
  integer/float arithmetic selection, and keep call shape driven by syntax
  instead of provisional inferred types.
- Preserve chained field declarations as static parser information when flow
  types are not yet available, including postfix field updates through calls.

Types, functions, and escape analysis

- Add `TypeScalar` as the common lattice family for integer, float, memory
  pointer, and function-pointer values, with scalar TOP/BOT values for generic
  Loads, Stores, parameters, and invalid intermediate expressions.
- Represent unresolved struct definitions directly with the `TypeStruct`
  forward-reference flag while retaining the separate open-structure concept;
  close and canonicalize recursive structures without side maps.
- Add explicit `FunPtrNode` references so constant function pointers retain a
  graph edge to their Return, and keep referenced functions alive until Opto
  proves the pointer dead.
- Refine public-function and class-initializer escape handling, including
  public-only fallback escape sets and monotone compilation-unit summaries.
- Add guards, proof casts, read-only propagation, pointer-to-integer conversion
  for non-null FFI arguments, and consistent deep mutability checks at calls.

Optimization and code generation

- Make weak and unresolved graph inputs compute conservatively and monotonically
  throughout iterative peepholes and SCCP.
- Preserve independent memory slices when sharpening Stores, retain control on
  conditional Stores, and freeze Store widths from their target field types.
- Extend serialization for new node kinds, scalar types, Store modes, function
  pointers, and memory partitions, preserving serialize/deserialize bijection.
- Complete native selection and encoding support across x86-64, RISC-V, and
  ARM, including FFI pointer conversion and missing integer operations.
- Fix x86 immediate multiply REX encoding and assorted scheduling, register
  allocation, spilling, relocation, and constant-pool issues exposed by the
  larger linked graphs.

System library, tests, and documentation

- Compile and link the Simple `sys` library, including libc bindings, I/O,
  scanners, strings, vectors, array helpers, and executable entry points.
- Add Chapter 25 module, serialization, constructor, forward-reference,
  postfix-update, system, Hello World, and Bubble Sort coverage; update golden
  graphs and spill expectations for the new IR shape.
- Add module and type-system documentation, parser-simplification design notes,
  grammar updates, examples, diagrams, and graph visualization assets.

The resulting compiler passes the raw Chapter 1-24 suite and the Chapter 25
system and separate-compilation tests, including a freshly rebuilt `sys.o` and
the native Bubble Sort example.

1 files changed, 66 insertions, 0 deletions

diff --git a/chapter25/src/main/smp/sys/aryu8.smp b/chapter25/src/main/smp/sys/aryu8.smp
new file mode 100644
index 00000000..0ce4bd23
--- /dev/null
+++ b/chapter25/src/main/smp/sys/aryu8.smp
@@ -0,0 +1,66 @@
+// -*- mode: java;  -*-
+
+// Ary/Vector of u8s - a resizable array of bytes.
+struct aryu8 {
+    u32 !len = 0;
+    u8[] !buf;
+
+    new aryu8 = { u8[] b ->
+        buf = b;
+    };
+
+    // Grow as needed
+    val _grow = { int len2 ->
+        if( len+len2 < buf# ) return self;
+        int newlen = buf# * 2;
+        while( len+len2 >= newlen ) newlen *= 2;
+        u8[] !buf2 = new u8[newlen];
+        Ary.copy(buf2,0,buf,0,buf#);
+        buf = buf2;
+        self;
+    };
+
+    val clear = { -> len = 0; self; };
+
+    // Add a character to aryu8
+    val add = { u8 c ->
+        _grow(1).buf[len++] = c;
+        self;
+    };
+
+    // Add all of a plain array to the aryu8
+    val addAry = { u8[~] ary ->
+        _grow(ary#);
+        Ary.copy(buf,len,ary,0,ary#);
+        len += ary#;
+        self;
+    };
+
+    // Remove x bytes from the tail.
+    val undo = { int x ->
+        len = len >= x ? len-x : 0;
+        self;
+    };
+
+    // Print ASCII number into aryu8
+    val num = { i64 x ->
+        if( !x ) { add('0'); return self; }
+        if( x < 0 ) { add('-'); x = -x; }
+        i64 ten = 1, log = 0;
+        while( ten <= x ) { ten *= 10; log++; }
+        for( int i=0; i<log; i++ ) {
+            ten /= 10;
+            i64 q = x/ten;
+            u8 digit = q+'0';
+            add(digit);
+            x -= q*ten;
+        }
+        self;
+    };
+
+    // Write to fd, returns the number of bytes written (len).
+    val write = { i32 fd ->
+        i64 ptr = buf; // Cast buffer pointer to i64 for native C call
+        libc.write(fd,ptr,len);
+    };
+};