Merge "Revert "Implement on-stack replacement for arm/arm64/x86/x86_64.""

1 files changed, 68 insertions, 0 deletions

diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index 8d77daf183..c7430e7eb6 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -72,6 +72,74 @@ class Temporaries : public ValueObject {
   size_t index_;
 };
 
+class SwitchTable : public ValueObject {
+ public:
+  SwitchTable(const Instruction& instruction, uint32_t dex_pc, bool sparse)
+      : instruction_(instruction), dex_pc_(dex_pc), sparse_(sparse) {
+    int32_t table_offset = instruction.VRegB_31t();
+    const uint16_t* table = reinterpret_cast<const uint16_t*>(&instruction) + table_offset;
+    if (sparse) {
+      CHECK_EQ(table[0], static_cast<uint16_t>(Instruction::kSparseSwitchSignature));
+    } else {
+      CHECK_EQ(table[0], static_cast<uint16_t>(Instruction::kPackedSwitchSignature));
+    }
+    num_entries_ = table[1];
+    values_ = reinterpret_cast<const int32_t*>(&table[2]);
+  }
+
+  uint16_t GetNumEntries() const {
+    return num_entries_;
+  }
+
+  void CheckIndex(size_t index) const {
+    if (sparse_) {
+      // In a sparse table, we have num_entries_ keys and num_entries_ values, in that order.
+      DCHECK_LT(index, 2 * static_cast<size_t>(num_entries_));
+    } else {
+      // In a packed table, we have the starting key and num_entries_ values.
+      DCHECK_LT(index, 1 + static_cast<size_t>(num_entries_));
+    }
+  }
+
+  int32_t GetEntryAt(size_t index) const {
+    CheckIndex(index);
+    return values_[index];
+  }
+
+  uint32_t GetDexPcForIndex(size_t index) const {
+    CheckIndex(index);
+    return dex_pc_ +
+        (reinterpret_cast<const int16_t*>(values_ + index) -
+         reinterpret_cast<const int16_t*>(&instruction_));
+  }
+
+  // Index of the first value in the table.
+  size_t GetFirstValueIndex() const {
+    if (sparse_) {
+      // In a sparse table, we have num_entries_ keys and num_entries_ values, in that order.
+      return num_entries_;
+    } else {
+      // In a packed table, we have the starting key and num_entries_ values.
+      return 1;
+    }
+  }
+
+ private:
+  const Instruction& instruction_;
+  const uint32_t dex_pc_;
+
+  // Whether this is a sparse-switch table (or a packed-switch one).
+  const bool sparse_;
+
+  // This can't be const as it needs to be computed off of the given instruction, and complicated
+  // expressions in the initializer list seemed very ugly.
+  uint16_t num_entries_;
+
+  const int32_t* values_;
+
+  DISALLOW_COPY_AND_ASSIGN(SwitchTable);
+};
+
 void HGraphBuilder::InitializeLocals(uint16_t count) {
   graph_->SetNumberOfVRegs(count);
   locals_.resize(count);