snapshot: preserve the uncommitted Canary instrumentation (not authored here)

Working-tree snapshot taken 2026-07-28 so this work is not lost. To be clear
about provenance: NONE of this was written in the session that committed it —
it is pre-existing uncommitted work on phase-a-tracing, last committed 2026-07-09,
from the xenia-rs decoder/deadlock investigation. It is recorded verbatim, not
reviewed and not tested.

Contents: 24 tracked modifications (ppc_emit_memory, xex_module, object_table,
shim_utils, xboxkrnl threading/rtl, xevent/xobject/xthread, memory) plus the
untracked probe sources audit_68_host_mem_watch, audit_69_event_signal_watch,
audit_70_semaphore_release_watch, phase_b_snapshot, and cmake/toolchains.

Deliberately excluded: build-cross/ (51 GB of build output) and
vkd3d-proton.cache. Note third_party/snappy is a submodule pointer change whose
target may not be pushed anywhere, so this branch is a preservation record rather
than a guaranteed-buildable tree.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tools/build/compile_shader_dxbc.py

@@ -72,15 +72,29 @@ def main():
     is_dxc = "dxc" in os.path.basename(fxc).lower()
 
     # Start with base command — use wine on non-Windows platforms.
+    # fxc.exe sees '/foo' as a switch, so unix-rooted paths must be
+    # translated to Windows form (Z:\...) before being passed.
     if sys.platform != "win32":
+        def _wineify(p):
+            try:
+                out = subprocess.check_output(["winepath", "-w", p],
+                                              stderr=subprocess.DEVNULL)
+                return out.decode("utf-8", "replace").strip()
+            except (OSError, subprocess.CalledProcessError):
+                return p
+        input_path = _wineify(input_path)
+        output_path = _wineify(output_path)
+        src_dir = _wineify(src_dir)
         compiler_args = ["wine", fxc]
     else:
         compiler_args = [fxc]
 
     if is_dxc:
-        # DXC only supports SM 6.0+.
+        # DXC supports both SM 5.x (-> DXBC) and SM 6.x (-> DXIL). xenia's D3D12
+        # backend reads DXBC (output dir is bytecode/d3d12_5_1/), so target
+        # SM 5_1 to keep DXBC parity with FXC output.
         compiler_args.extend([
-            "-T", f"{stage}_6_0",
+            "-T", f"{stage}_5_1",
             "-HV", "2017",
             "-D", "SHADING_LANGUAGE_HLSL_XE=1",
             "-I", src_dir,