[PATCH] D159543: [BOLT] Fix .relr section addend patching

[Maksim Panchenko via Phabricator via llvm-commits]

maksfb added inline comments.


================
Comment at: bolt/lib/Core/BinaryEmitter.cpp:322-328
+  if (Function.size() == 0 && Function.hasIslandsInfo()) {
+    // If function has only constant island emit alignment before emitting
+    // symbols, so the emitted nops (if any) won't be part of the constant
+    // islands data and we would address data correctly.
+    const uint16_t Alignment = Function.getConstantIslandAlignment();
+    Streamer.emitCodeAlignment(Align(Alignment), &*BC.STI);
+  }
----------------
The code in `AlignerPass` tries to address the same issue: https://github.com/llvm/llvm-project/blob/b7961f2cb97556bfc50f7828d5f869d96ab9352e/bolt/lib/Passes/Aligner.cpp#L166-L171

That code doesn't work because having 64-byte alignment with max 8-byte alignment will often do nothing.


What if the function is not empty, would we have a similar issue with alignment issued before the symbol?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D159543/new/

https://reviews.llvm.org/D159543