X86 jump tables for PackedSwitch
Implement X86PackedSwitch using a jump table of offsets to blocks. The
X86PackedSwitch version just adds an input to address the constant area.
Change-Id: Id2752a1ee79222493040c6fd0e59aee9a544b76a
Bug: 21119474
Signed-off-by: Mark Mendell <mark.p.mendell@intel.com>
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index f8be21a..b60eebf 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -521,7 +521,8 @@
move_resolver_(graph->GetArena(), this),
isa_features_(isa_features),
method_patches_(graph->GetArena()->Adapter(kArenaAllocCodeGenerator)),
- relative_call_patches_(graph->GetArena()->Adapter(kArenaAllocCodeGenerator)) {
+ relative_call_patches_(graph->GetArena()->Adapter(kArenaAllocCodeGenerator)),
+ fixups_to_jump_tables_(graph->GetArena()->Adapter(kArenaAllocCodeGenerator)) {
// Use a fake return address register to mimic Quick.
AddAllocatedRegister(Location::RegisterLocation(kFakeReturnRegister));
}
@@ -5669,6 +5670,51 @@
}
}
+void LocationsBuilderX86::VisitX86PackedSwitch(HX86PackedSwitch* switch_instr) {
+ LocationSummary* locations =
+ new (GetGraph()->GetArena()) LocationSummary(switch_instr, LocationSummary::kNoCall);
+ locations->SetInAt(0, Location::RequiresRegister());
+
+ // Constant area pointer.
+ locations->SetInAt(1, Location::RequiresRegister());
+
+ // And the temporary we need.
+ locations->AddTemp(Location::RequiresRegister());
+}
+
+void InstructionCodeGeneratorX86::VisitX86PackedSwitch(HX86PackedSwitch* switch_instr) {
+ int32_t lower_bound = switch_instr->GetStartValue();
+ int32_t num_entries = switch_instr->GetNumEntries();
+ LocationSummary* locations = switch_instr->GetLocations();
+ Register value_reg = locations->InAt(0).AsRegister<Register>();
+ HBasicBlock* default_block = switch_instr->GetDefaultBlock();
+
+ // Optimizing has a jump area.
+ Register temp_reg = locations->GetTemp(0).AsRegister<Register>();
+ Register constant_area = locations->InAt(1).AsRegister<Register>();
+
+ // Remove the bias, if needed.
+ if (lower_bound != 0) {
+ __ leal(temp_reg, Address(value_reg, -lower_bound));
+ value_reg = temp_reg;
+ }
+
+ // Is the value in range?
+ DCHECK_GE(num_entries, 1);
+ __ cmpl(value_reg, Immediate(num_entries - 1));
+ __ j(kAbove, codegen_->GetLabelOf(default_block));
+
+ // We are in the range of the table.
+ // Load (target-constant_area) from the jump table, indexing by the value.
+ __ movl(temp_reg, codegen_->LiteralCaseTable(switch_instr, constant_area, value_reg));
+
+ // Compute the actual target address by adding in constant_area.
+ __ addl(temp_reg, constant_area);
+
+ // And jump.
+ __ jmp(temp_reg);
+}
+
void LocationsBuilderX86::VisitX86ComputeBaseMethodAddress(
HX86ComputeBaseMethodAddress* insn) {
LocationSummary* locations =
@@ -5752,28 +5798,18 @@
}
}
-void CodeGeneratorX86::Finalize(CodeAllocator* allocator) {
- // Generate the constant area if needed.
- X86Assembler* assembler = GetAssembler();
- if (!assembler->IsConstantAreaEmpty()) {
- // Align to 4 byte boundary to reduce cache misses, as the data is 4 and 8
- // byte values.
- assembler->Align(4, 0);
- constant_area_start_ = assembler->CodeSize();
- assembler->AddConstantArea();
- }
-
- // And finish up.
- CodeGenerator::Finalize(allocator);
-}
-
/**
* Class to handle late fixup of offsets into constant area.
*/
class RIPFixup : public AssemblerFixup, public ArenaObject<kArenaAllocCodeGenerator> {
public:
- RIPFixup(const CodeGeneratorX86& codegen, int offset)
- : codegen_(codegen), offset_into_constant_area_(offset) {}
+ RIPFixup(CodeGeneratorX86& codegen, size_t offset)
+ : codegen_(&codegen), offset_into_constant_area_(offset) {}
+
+ protected:
+ void SetOffset(size_t offset) { offset_into_constant_area_ = offset; }
+
+ CodeGeneratorX86* codegen_;
private:
void Process(const MemoryRegion& region, int pos) OVERRIDE {
@@ -5781,19 +5817,77 @@
// last 4 bytes of the instruction.
// The value to patch is the distance from the offset in the constant area
// from the address computed by the HX86ComputeBaseMethodAddress instruction.
- int32_t constant_offset = codegen_.ConstantAreaStart() + offset_into_constant_area_;
- int32_t relative_position = constant_offset - codegen_.GetMethodAddressOffset();;
+ int32_t constant_offset = codegen_->ConstantAreaStart() + offset_into_constant_area_;
+ int32_t relative_position = constant_offset - codegen_->GetMethodAddressOffset();;
// Patch in the right value.
region.StoreUnaligned<int32_t>(pos - 4, relative_position);
}
- const CodeGeneratorX86& codegen_;
-
// Location in constant area that the fixup refers to.
- int offset_into_constant_area_;
+ int32_t offset_into_constant_area_;
};
+/**
+ * Class to handle late fixup of offsets to a jump table that will be created in the
+ * constant area.
+ */
+class JumpTableRIPFixup : public RIPFixup {
+ public:
+ JumpTableRIPFixup(CodeGeneratorX86& codegen, HX86PackedSwitch* switch_instr)
+ : RIPFixup(codegen, static_cast<size_t>(-1)), switch_instr_(switch_instr) {}
+
+ void CreateJumpTable() {
+ X86Assembler* assembler = codegen_->GetAssembler();
+
+ // Ensure that the reference to the jump table has the correct offset.
+ const int32_t offset_in_constant_table = assembler->ConstantAreaSize();
+ SetOffset(offset_in_constant_table);
+
+ // The label values in the jump table are computed relative to the
+ // instruction addressing the constant area.
+ const int32_t relative_offset = codegen_->GetMethodAddressOffset();
+
+ // Populate the jump table with the correct values for the jump table.
+ int32_t num_entries = switch_instr_->GetNumEntries();
+ HBasicBlock* block = switch_instr_->GetBlock();
+ const ArenaVector<HBasicBlock*>& successors = block->GetSuccessors();
+ // The value that we want is the target offset - the position of the table.
+ for (int32_t i = 0; i < num_entries; i++) {
+ HBasicBlock* b = successors[i];
+ Label* l = codegen_->GetLabelOf(b);
+ DCHECK(l->IsBound());
+ int32_t offset_to_block = l->Position() - relative_offset;
+ assembler->AppendInt32(offset_to_block);
+ }
+ }
+
+ private:
+ const HX86PackedSwitch* switch_instr_;
+};
+
+void CodeGeneratorX86::Finalize(CodeAllocator* allocator) {
+ // Generate the constant area if needed.
+ X86Assembler* assembler = GetAssembler();
+ if (!assembler->IsConstantAreaEmpty() || !fixups_to_jump_tables_.empty()) {
+ // Align to 4 byte boundary to reduce cache misses, as the data is 4 and 8
+ // byte values.
+ assembler->Align(4, 0);
+ constant_area_start_ = assembler->CodeSize();
+
+ // Populate any jump tables.
+ for (auto jump_table : fixups_to_jump_tables_) {
+ jump_table->CreateJumpTable();
+ }
+
+ // And now add the constant area to the generated code.
+ assembler->AddConstantArea();
+ }
+
+ // And finish up.
+ CodeGenerator::Finalize(allocator);
+}
+
Address CodeGeneratorX86::LiteralDoubleAddress(double v, Register reg) {
AssemblerFixup* fixup = new (GetGraph()->GetArena()) RIPFixup(*this, __ AddDouble(v));
return Address(reg, kDummy32BitOffset, fixup);
@@ -5814,6 +5908,20 @@
return Address(reg, kDummy32BitOffset, fixup);
}
+Address CodeGeneratorX86::LiteralCaseTable(HX86PackedSwitch* switch_instr,
+ Register reg,
+ Register value) {
+ // Create a fixup to be used to create and address the jump table.
+ JumpTableRIPFixup* table_fixup =
+ new (GetGraph()->GetArena()) JumpTableRIPFixup(*this, switch_instr);
+
+ // We have to populate the jump tables.
+ fixups_to_jump_tables_.push_back(table_fixup);
+
+ // We want a scaled address, as we are extracting the correct offset from the table.
+ return Address(reg, value, TIMES_4, kDummy32BitOffset, table_fixup);
+}
+
/**
* Finds instructions that need the constant area base as an input.
*/
@@ -5864,6 +5972,21 @@
}
}
+ void VisitPackedSwitch(HPackedSwitch* switch_insn) OVERRIDE {
+ // We need to replace the HPackedSwitch with a HX86PackedSwitch in order to
+ // address the constant area.
+ InitializeConstantAreaPointer(switch_insn);
+ HGraph* graph = GetGraph();
+ HBasicBlock* block = switch_insn->GetBlock();
+ HX86PackedSwitch* x86_switch = new (graph->GetArena()) HX86PackedSwitch(
+ switch_insn->GetStartValue(),
+ switch_insn->GetNumEntries(),
+ switch_insn->InputAt(0),
+ base_,
+ switch_insn->GetDexPc());
+ block->ReplaceAndRemoveInstructionWith(switch_insn, x86_switch);
+ }
+
void InitializeConstantAreaPointer(HInstruction* user) {
// Ensure we only initialize the pointer once.
if (base_ != nullptr) {