[optimizing] Add basic PackedSwitch support
Add HPackedSwitch, and generate it from the builder. Code generators
convert this to a series of compare/branch tests. Better implementation
in the code generators as a real jump table will follow as separate CLs.
Change-Id: If14736fa4d62809b6ae95280148c55682e856911
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>
diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index 274a2a6..9d70124 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -1685,6 +1685,34 @@
dex_compilation_unit_->GetDexMethodIndex(), *dex_file_, type_index);
}
+void HGraphBuilder::BuildSwitchJumpTable(const SwitchTable& table,
+ const Instruction& instruction,
+ HInstruction* value,
+ uint32_t dex_pc) {
+ // Add the successor blocks to the current block.
+ uint16_t num_entries = table.GetNumEntries();
+ for (size_t i = 1; i <= num_entries; i++) {
+ int32_t target_offset = table.GetEntryAt(i);
+ HBasicBlock* case_target = FindBlockStartingAt(dex_pc + target_offset);
+ DCHECK(case_target != nullptr);
+
+ // Add the target block as a successor.
+ current_block_->AddSuccessor(case_target);
+ }
+
+ // Add the default target block as the last successor.
+ HBasicBlock* default_target = FindBlockStartingAt(dex_pc + instruction.SizeInCodeUnits());
+ DCHECK(default_target != nullptr);
+ current_block_->AddSuccessor(default_target);
+
+ // Now add the Switch instruction.
+ int32_t starting_key = table.GetEntryAt(0);
+ current_block_->AddInstruction(
+ new (arena_) HPackedSwitch(starting_key, num_entries, value, dex_pc));
+ // This block ends with control flow.
+ current_block_ = nullptr;
+}
+
void HGraphBuilder::BuildPackedSwitch(const Instruction& instruction, uint32_t dex_pc) {
// Verifier guarantees that the payload for PackedSwitch contains:
// (a) number of entries (may be zero)
@@ -1695,18 +1723,24 @@
// Value to test against.
HInstruction* value = LoadLocal(instruction.VRegA(), Primitive::kPrimInt, dex_pc);
+ // Starting key value.
+ int32_t starting_key = table.GetEntryAt(0);
+
// Retrieve number of entries.
uint16_t num_entries = table.GetNumEntries();
if (num_entries == 0) {
return;
}
- // Chained cmp-and-branch, starting from starting_key.
- int32_t starting_key = table.GetEntryAt(0);
-
- for (size_t i = 1; i <= num_entries; i++) {
- BuildSwitchCaseHelper(instruction, i, i == num_entries, table, value, starting_key + i - 1,
- table.GetEntryAt(i), dex_pc);
+ // Don't use a packed switch if there are very few entries.
+ if (num_entries > kSmallSwitchThreshold) {
+ BuildSwitchJumpTable(table, instruction, value, dex_pc);
+ } else {
+ // Chained cmp-and-branch, starting from starting_key.
+ for (size_t i = 1; i <= num_entries; i++) {
+ BuildSwitchCaseHelper(instruction, i, i == num_entries, table, value,
+ starting_key + i - 1, table.GetEntryAt(i), dex_pc);
+ }
}
}