Squashed commit of the following:

commit c05d7df4f9c90984d2c04126772be3fee1d81fd1
Author: Cliff Click <cliffc@acm.org>
Date:   Thu Aug 20 10:52:58 2026 -0700

    Fix local frefs, deferred inlining, and sys FileIO support

    - Defer non-trivial inlining out of CallEnd idealization and run it from IterPeeps after normal peepholes reach a fixed point.
    - Keep forward refs local to their lexical scope, promote them outward on scope pop, and track created FRefNodes directly for dependency  discovery.
    - Preserve loop scope shape when frefs are first seen inside loop bodies.
    - Treat frefs as final constants from creation and force lazy self lookups before implicit calls.
    - Reset imported pointer/struct types conservatively for post-parse Iter.
    - Pin Start-owned global machine value chains and clone global constants per function during GCM.
    - Improve late ASM printing before encoding and namespace constant-pool symbols.
    - Add optional regalloc function-local edge verifier and improve empty-mask splitting for multi-def/fixed-register LRGs.
    - Add sys array compare, safer array copy bounds, libc open/creat/close/unlink bindings, aryu8.str0, and higher-level sys.io file operations.
    - Add docs/examples/FileIO.smp and a Chapter25 FileIO test.
    - Update spill/code-size goldens after the allocator and scheduling changes.

commit ef5316979732ac118612d310b75923c8f59ecdc1
Author: Cliff Click <cliffc@acm.org>
Date:   Fri Aug 14 16:29:56 2026 -0700

    Dijkstra uses bitset.

    TestC.exec for repeated test runs with different stdins.
    Support &= and |= op-update forms.

commit 728a527587f19bb49860f02ae5ac5968ab01ae33
Author: Cliff Click <cliffc@acm.org>
Date:   Fri Aug 14 12:13:28 2026 -0700

    Fix live demo

commit e4c069b9ef2cbfafe28d8edfcbff55396cde085e
Author: Cliff Click <cliffc@acm.org>
Date:   Fri Aug 14 09:52:24 2026 -0700

    Update Dijkstra.smp

commit b8015739b4056e3f7a715a030e846a441021a9f1
Author: Cliff Click <cliffc@acm.org>
Date:   Fri Aug 14 09:41:17 2026 -0700

    Better looking Dijkstra

commit 7cce587804c6169b24829e0b5bdc10be94357a31
Author: Cliff Click <cliffc@acm.org>
Date:   Fri Aug 14 09:33:33 2026 -0700

    Fix CmpMemX86 encoding

    Use sys.aryu8 for number printing

commit 310b5d8c9978a3b09622a4b89dac97f0e5e6f3fb
Author: Cliff Click <cliffc@acm.org>
Date:   Fri Aug 14 09:04:58 2026 -0700

    Progress dijlstra

    Fix NotX86 encoding.  Allow Not-sinking through Phis; the Nots both take Scalar and might take different types (ptr vs int).  Better guard installing during && || opers.
    Drop the csv parse flavor in sys lib.

commit 5917d5322521dd5e762c4698d34e5d7ac9b3a37f
Author: Cliff Click <cliffc@acm.org>
Date:   Thu Aug 13 14:44:12 2026 -0700

    missed

commit da35ad4d8a330559a21c04ae6326536e0fd62c48
Author: Cliff Click <cliffc@acm.org>
Date:   Thu Aug 13 14:43:42 2026 -0700

    Major cleanup of allocation

    All the graph-gen is moved to the <ctor> declaration and not at the alloc site.

commit c4223216099ccbc526d282bb263972532d48c5b2
Author: Cliff Click <cliffc@acm.org>
Date:   Thu Aug 13 13:26:01 2026 -0700

    Some work from Dykstra (more coming)

commit a03bc567f61dc7e4355e453ee4be16ac2528d1ab
Author: Cliff Click <cliffc@acm.org>
Date:   Thu Aug 13 09:32:55 2026 -0700

    Spill correctness and improvements

    Had the callee-save pick-risky backwards vs cloneables.

commit 2d306e4430225f916cb7fb999f4926e52f6fb70a
Author: Cliff Click <cliffc@acm.org>
Date:   Wed Aug 12 19:40:04 2026 -0700

    Tighter parser handling of missing fields

    Bug fix add libc.errno, read can return -1, sys.ary exists

commit b7eeefda4cafa1e86153170dca6f13d45ef63f69
Author: Cliff Click <cliffc@acm.org>
Date:   Wed Aug 12 16:22:48 2026 -0700

    Printer improvements

commit 8b9112226f1d2d1c843b080eecefe0d5ddc1f8cf
Author: Cliff Click <cliffc@acm.org>
Date:   Wed Aug 12 15:30:46 2026 -0700

    Remove GLB

commit ae566f5c610b9c30831906d3f024901d8930a227
Author: Cliff Click <cliffc@acm.org>
Date:   Wed Aug 12 14:38:51 2026 -0700

    Add Capitalize example

    Rename Ary to ary.
    Fix bug || carrying state along.
    Fix bug load-array removing control.
    Add sys.char tolower/upper

1 files changed, 26 insertions, 2 deletions

diff --git a/chapter25/src/main/smp/sys/libc.smp b/chapter25/src/main/smp/sys/libc.smp
index 42fc7313..6d750f7b 100644
--- a/chapter25/src/main/smp/sys/libc.smp
+++ b/chapter25/src/main/smp/sys/libc.smp
@@ -3,12 +3,36 @@
 // libc bindings:
 //   https://www.man7.org/linux/man-pages/man2/<libc call>.2.html
 
+// The buffers are int-versions of zero-terminated strings.
+//     int buf = aryu8.str0("some_file");
+// buf mode perm-> fd
+{  i64 i32  i32 -> i32 } open = "C";
+// buf perm -> fd
+{  i64 i32 -> i32 } creat = "C";
+
 // fd  buf len -> len
-{  i32 i64 u32 -> u32 } write = "C";
+{  i32 i64 u32 -> i32 } write = "C";
 // fd  buf len -> len
-{  i32 i64 u32 -> u32 } read = "C";
+{  i32 i64 u32 -> i32 } read = "C";
+// fd  -> err
+{  i32 -> i32 } close = "C";
+// path -> err
+{  i64 -> i32 } unlink = "C";
+
+i32 O_RDONLY = 0;
+i32 O_WRONLY = 1;
+i32 O_RDWR   = 2;
+i32 O_CREAT = 512; // 02000 on x86_64-pc-cygwin
+i32 O_TRUNC = 1024; // 04000 on x86_64-pc-cygwin
+
+i32 STDIN  = 0;
+i32 STDOUT = 1;
+i32 STDERR = 2;
+
 // status
 {  i32 -> i32 } _exit = "C";
+// Error return from many native calls
+i32 errno = "C";
 // addr len prot flags fd  off -> void*
 {  i64  i64 i32  i32   i32 i32 -> i64 } mmap = "C";
 // mmap flags