Move SASS diff description to a SKILL

.agent/skills/sass-diff/SKILL.md

@@ -0,0 +1,50 @@
+---
+name: sass-diff
+description: Use when asked to check for SASS (or PTX) changes between commits, branches, or a local changeset; guides normalization, comparison, and reporting of CUDA disassembly diffs.
+---
+
+# SASS Diffs
+
+Use this when asked to check for SASS changes between commits, branches or a local changeset.
+
+## Goal
+
+Detect relevant changes in generated CUDA machine code (i.e. SASS) while filtering noise from addresses, symbols, metadata, etc.
+Any non-trivial change must be detected.
+
+## Inputs to establish
+
+* Compilation target under test
+* The CUDA SM architectures to compile for. Try to detect this from the code and offer the user a list of suggestions.
+  The user must confirm or provide this list.
+* Baseline source (e.g. the previous commit/branch or the current commit without the changes in the working copy).
+* Comparison source (e.g.  the current commit/branch or the current commit with the changes in the working copy).
+* Whether a SASS (default) or PTX diff is requested.
+
+## Disassembly listing generation
+
+* Compile both, the baseline and comparison source, with the same compiler flags and options.
+  When not specified otherwise, lookup the options from `compile_commands.json`
+  or the current build system (i.e. CMake files).
+  Make sure the CUDA SM architectures (`CMAKE_CUDA_ARCHITECTURES`) are set to the user-provided or approved list.
+* Dump the disassembly from the binaries produced in the previous set using `cuobjdump -sass` or `cuobjdump -ptx`.
+
+## Comparison rules (what matters)
+
+Ignore as trivial:
+
+* Register renaming with identical instruction sequence and operands.
+* Pure label renumbering or reordering of identical basic blocks.
+* Formatting-only differences or reordered symbol tables.
+* Changes to symbol names (global function names)
+
+## Reporting
+
+* If any non-trivial change was detected, report the top 5 regions where a non-trivial change was detected,
+  including the name of the kernel they appeared in.
+* Provide a short summary of the diff type,
+  including opcode changes, memory access size/cache policy changes, control-flow changes, register-count changes,
+  spills/local memory, shared memory, and occupancy-relevant resource deltas.
+* Explicitly state if only noise was detected.
+* If you are not sure if the differences are impactful, show it and ask the user for guidance.
+* Keep the disassembly dumps available and tell the user where they can find them.

AGENTS.md

@@ -273,54 +273,6 @@ Test organization:
 
 ---
 
-## SASS Diffs
-
-Use this test when asked to check for SASS changes between commits, branches or a local changeset.
-
-### Goal
-
-Detect relevant changes in generated CUDA machine code (i.e. SASS) while filtering noise from addresses, symbols, metadata, etc.
-Any non-trivial change must be detected.
-
-### Inputs to establish
-
-* Compiled binary under test
-* The CUDA SM architectures to compile for. Try to detect this from the code and offer the user a list of suggestions.
-  The user must conform or provide this list.
-* Baseline disassembly (from the previous commit/branch or the current commit without the changes in the working copy).
-* Comparison disassembly (form the current commit/branch or the current commit with the changes in the working copy).
-* By default, prefer `cuobjdump -sass` to inspect SASS changes.
-  Use `cuobjdump -ptx` if the request is to check for PTX changes instead.
-
-### Normalization rules (strip known noise)
-
-Apply these transforms to both baseline and candidate listings before diffing.
-Write the normalized listings to separate files.
-
-* Remove addresses/offsets/hex location prefixes.
-* Remove build IDs, timestamps, absolute paths, temp directories, and compiler banners.
-* Normalize whitespace and alignment to single spaces.
-* Remove empty lines and purely comment lines.
-
-### Comparison rules (what matters)
-
-Ignore as trivial:
-
-* Register renaming with identical instruction sequence and operands.
-* Pure label renumbering or reordering of identical basic blocks.
-* Formatting-only differences or reordered symbol tables.
-
-### Reporting
-
-* If any non-trivial change was detected, the top 5 regions where a non-trivial change was detected,
-  including the name of the kernel they appeared in.
-* A short summary of the diff type (opcode change, memory access size change, size delta, control-flow, etc.).
-* Explicitly state if only noise was detected after normalization.
-* If you are not sure if the differences are impactful, show it and ask the user for guidance.
-* Keep the disassembly dumps available for reference and show the command to the user to generate a diff.
-
----
-
 ## Continuous Integration (CI)
 
 See `ci-overview.md` for detailed examples and troubleshooting guidance.