[llvm] c4babfb - [Docs] Document persistent metadata printing (#220967)

[via llvm-commits]

Author: Yaxun (Sam) Liu
Date: 2026-09-08T08:53:59-04:00
New Revision: c4babfb3128b9b167e469003028dbaf4e14a6167

URL: https://github.com/llvm/llvm-project/commit/c4babfb3128b9b167e469003028dbaf4e14a6167
DIFF: https://github.com/llvm/llvm-project/commit/c4babfb3128b9b167e469003028dbaf4e14a6167.diff

LOG: [Docs] Document persistent metadata printing (#220967)

Document how persistent metadata IDs affect intermediate and standalone
textual output. Final assembly output remains canonically renumbered.

Follow-up to #220390.

Added: 
    

Modified: 
    llvm/docs/ReleaseNotes.md

Removed: 
    


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diff  --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md
index 9f1611e4cab7f..607bb0e30b058 100644
--- a/llvm/docs/ReleaseNotes.md
+++ b/llvm/docs/ReleaseNotes.md
@@ -52,6 +52,26 @@ Makes programs 10x faster by doing Special New Thing.
 
 ### Changes to the LLVM IR
 
+* LLVM now assigns persistent print IDs to metadata nodes. Reusing these IDs
+  avoids repeated module-wide scans to rebuild metadata numbering, which can
+  significantly speed up debug and pass printing on large modules. Keeping
+  the IDs stable also makes repeated output easier to compare: unchanged
+  metadata keeps the same number as passes modify the module. The numbering
+  and definition order can 
diff er from earlier releases, so tests of
+  intermediate output may need updated expectations.
+
+  LLVM's standard final-output paths renumber metadata in canonical order.
+  This gives consecutive IDs with no gaps and makes the final IR easier to
+  read. C++ clients that call `Module::print()` directly do not renumber
+  automatically. For final IR output, these clients should call
+  `Module::renumberMetadataForAssembly()` immediately before printing. Keep
+  persistent IDs for intermediate dumps so their numbering remains stable.
+
+  Standalone metadata printing now uses numbered definitions such as
+  `!1 = !DIFile(...)` instead of pointer-based forms such as
+  `<0x...> = !DIFile(...)`. Tools and tests that compare such output may need
+  updating.
+
 * Added `llvm.vector.reduce.fmaximumnum` and `llvm.vector.reduce.fminimumnum`
   intrinsics, the reduction variants of `llvm.maximumnum` and
   `llvm.minimumnum`.