[wasm][liftoff] Implement data.drop

R=clemensb@chromium.org

Bug: v8:10281
Change-Id: I34e6d1ec57d59e266d3182a3d3cc69d4cbb9d047
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2104889
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66728}

src/wasm/baseline/liftoff-compiler.cc

@@ -2764,7 +2764,23 @@ class LiftoffCompiler {
   }
 
   void DataDrop(FullDecoder* decoder, const DataDropImmediate<validate>& imm) {
-    unsupported(decoder, kBulkMemory, "data.drop");
+    LiftoffRegList pinned;
+
+    Register seg_size_array =
+        pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
+    LOAD_INSTANCE_FIELD(seg_size_array, DataSegmentSizes, kSystemPointerSize);
+
+    LiftoffRegister seg_index =
+        pinned.set(__ GetUnusedRegister(kGpReg, pinned));
+    // Scale the seg_index for the array access.
+    __ LoadConstant(seg_index,
+                    WasmValue(imm.index << kWasmI32.element_size_log2()));
+
+    // Set the length of the segment to '0' to drop it.
+    LiftoffRegister null_reg = pinned.set(__ GetUnusedRegister(kGpReg, pinned));
+    __ LoadConstant(null_reg, WasmValue(0));
+    __ Store(seg_size_array, seg_index.gp(), 0, null_reg, StoreType::kI32Store,
+             pinned);
   }
 
   void MemoryCopy(FullDecoder* decoder,