From e043a7453ea5c4bf5b04130a5e3b1c86a36ab181 Mon Sep 17 00:00:00 2001
From: Alexander Markov <alexmarkov@google.com>
Date: Tue, 9 Jun 2026 10:29:39 -0700
Subject: [PATCH] [vm] Cleanup unused UntaggedPcDescriptors::kBSSRelocation

TEST=ci

Change-Id: Ifd926f3bd3630b80c9659dbe60892c3c229bf838
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/510400
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
---
 runtime/vm/code_descriptors.cc |  4 +---
 runtime/vm/image_snapshot.cc   | 33 +--------------------------------
 runtime/vm/object.cc           |  2 --
 runtime/vm/raw_object.h        |  4 +---
 4 files changed, 3 insertions(+), 40 deletions(-)

diff --git a/runtime/vm/code_descriptors.cc b/runtime/vm/code_descriptors.cc
index 2951a3f4e37..44a1fe04785 100644
--- a/runtime/vm/code_descriptors.cc
+++ b/runtime/vm/code_descriptors.cc
@@ -40,7 +40,6 @@ void DescriptorList::AddDescriptor(UntaggedPcDescriptors::Kind kind,
   RELEASE_ASSERT(yield_index != 0);
 
   ASSERT((kind == UntaggedPcDescriptors::kRuntimeCall) ||
-         (kind == UntaggedPcDescriptors::kBSSRelocation) ||
          (kind == UntaggedPcDescriptors::kOther) ||
          (yield_index != UntaggedPcDescriptors::kInvalidYieldIndex) ||
          (deopt_id != DeoptId::kNone));
@@ -48,8 +47,7 @@ void DescriptorList::AddDescriptor(UntaggedPcDescriptors::Kind kind,
   // When precompiling, we only use pc descriptors for exceptions,
   // relocations and yield indices.
   if (!FLAG_precompiled_mode || try_index != -1 ||
-      yield_index != UntaggedPcDescriptors::kInvalidYieldIndex ||
-      kind == UntaggedPcDescriptors::kBSSRelocation) {
+      yield_index != UntaggedPcDescriptors::kInvalidYieldIndex) {
     const int32_t kind_and_metadata =
         UntaggedPcDescriptors::KindAndMetadata::Encode(kind, try_index,
                                                        yield_index);
diff --git a/runtime/vm/image_snapshot.cc b/runtime/vm/image_snapshot.cc
index 1a29c7a1988..4fbf025428a 100644
--- a/runtime/vm/image_snapshot.cc
+++ b/runtime/vm/image_snapshot.cc
@@ -867,10 +867,6 @@ void ImageWriter::WriteText(bool vm) {
   FrameUnwindPrologue();
 #endif
 
-#if defined(DART_PRECOMPILER)
-  PcDescriptors& descriptors = PcDescriptors::Handle(zone_);
-#endif
-
   // We don't expect more than 64 bytes of padding.
   uint8_t padding_bytes[64];
   memset(&padding_bytes[0], 0, sizeof(padding_bytes));
@@ -959,34 +955,7 @@ void ImageWriter::WriteText(bool vm) {
       // target-sized words starting from that address.
       ASSERT(Utils::IsAligned(payload_start, compiler::target::kWordSize));
       const uword payload_size = insns.Size();
-      auto const payload_end = payload_start + payload_size;
-      auto cursor = payload_start;
-#if defined(DART_PRECOMPILER)
-      descriptors = code.pc_descriptors();
-      PcDescriptors::Iterator iterator(
-          descriptors, /*kind_mask=*/UntaggedPcDescriptors::kBSSRelocation);
-      while (iterator.MoveNext()) {
-        // We only generate BSS relocations in the precompiler.
-        ASSERT(FLAG_precompiled_mode);
-        auto const next_reloc_offset = iterator.PcOffset();
-        auto const next_reloc_address = payload_start + next_reloc_offset;
-        // We only generate BSS relocations that are target word-sized and at
-        // target word-aligned offsets in the payload. Double-check this.
-        ASSERT(
-            Utils::IsAligned(next_reloc_address, compiler::target::kWordSize));
-        text_offset += WriteBytes(cursor, next_reloc_address - cursor);
-
-        // The instruction stream at the relocation position holds the target
-        // offset into the BSS section.
-        const auto target_offset =
-            *reinterpret_cast<const compiler::target::word*>(
-                next_reloc_address);
-        text_offset += Relocation(text_offset, instructions_label, text_offset,
-                                  bss_label, target_offset);
-        cursor = next_reloc_address + compiler::target::kWordSize;
-      }
-#endif
-      text_offset += WriteBytes(cursor, payload_end - cursor);
+      text_offset += WriteBytes(payload_start, payload_size);
     }
 
     // 4. Add appropriate padding. Note we can't simply copy from the object
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 35654dc3345..6256dba1e6a 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -16326,8 +16326,6 @@ const char* PcDescriptors::KindAsStr(UntaggedPcDescriptors::Kind kind) {
       return "osr-entry";
     case UntaggedPcDescriptors::kRewind:
       return "rewind";
-    case UntaggedPcDescriptors::kBSSRelocation:
-      return "bss reloc";
     case UntaggedPcDescriptors::kOther:
       return "other";
     case UntaggedPcDescriptors::kAnyKind:
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index 1bcad00381f..52d54c74f06 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -2260,9 +2260,7 @@ class UntaggedPcDescriptors : public UntaggedObject {
   V(OsrEntry, kRuntimeCall << 1)                                               \
   /* Call rewind target address. */                                            \
   V(Rewind, kOsrEntry << 1)                                                    \
-  /* Target-word-size relocation. */                                           \
-  V(BSSRelocation, kRewind << 1)                                               \
-  V(Other, kBSSRelocation << 1)                                                \
+  V(Other, kRewind << 1)                                                       \
   V(AnyKind, -1)
 
   enum Kind {