ARM: Link-time generated thunks for Baker CC read barrier.
Remaining work for follow-up CLs:
- use implicit null check in field thunk,
- use 16-bit LDRs for fields and GC roots.
Test: m test-art-target-gtest
Test: testrunner.py --target on Nexus 6P.
Test: testrunner.py --target on Nexus 6P with heap poisoning enabled.
Test: Repeat the above tests with ART_USE_OLD_ARM_BACKEND=true.
Bug: 29516974
Bug: 30126666
Bug: 36141117
Change-Id: Iad5addab72d790a9d61879f61f2e75b246bcdf5a
diff --git a/compiler/linker/arm/relative_patcher_thumb2.h b/compiler/linker/arm/relative_patcher_thumb2.h
index ab37802..9eb0689 100644
--- a/compiler/linker/arm/relative_patcher_thumb2.h
+++ b/compiler/linker/arm/relative_patcher_thumb2.h
@@ -17,6 +17,10 @@
#ifndef ART_COMPILER_LINKER_ARM_RELATIVE_PATCHER_THUMB2_H_
#define ART_COMPILER_LINKER_ARM_RELATIVE_PATCHER_THUMB2_H_
+#include "arch/arm/registers_arm.h"
+#include "base/array_ref.h"
+#include "base/bit_field.h"
+#include "base/bit_utils.h"
#include "linker/arm/relative_patcher_arm_base.h"
namespace art {
@@ -24,6 +28,37 @@
class Thumb2RelativePatcher FINAL : public ArmBaseRelativePatcher {
public:
+ static constexpr uint32_t kBakerCcEntrypointRegister = 4u;
+
+ enum class BakerReadBarrierKind : uint8_t {
+ kField, // Field get or array get with constant offset (i.e. constant index).
+ kArray, // Array get with index in register.
+ kGcRoot, // GC root load.
+ kLast
+ };
+
+ static uint32_t EncodeBakerReadBarrierFieldData(uint32_t base_reg, uint32_t holder_reg) {
+ CheckValidReg(base_reg);
+ CheckValidReg(holder_reg);
+ return BakerReadBarrierKindField::Encode(BakerReadBarrierKind::kField) |
+ BakerReadBarrierFirstRegField::Encode(base_reg) |
+ BakerReadBarrierSecondRegField::Encode(holder_reg);
+ }
+
+ static uint32_t EncodeBakerReadBarrierArrayData(uint32_t base_reg) {
+ CheckValidReg(base_reg);
+ return BakerReadBarrierKindField::Encode(BakerReadBarrierKind::kArray) |
+ BakerReadBarrierFirstRegField::Encode(base_reg) |
+ BakerReadBarrierSecondRegField::Encode(kInvalidEncodedReg);
+ }
+
+ static uint32_t EncodeBakerReadBarrierGcRootData(uint32_t root_reg) {
+ CheckValidReg(root_reg);
+ return BakerReadBarrierKindField::Encode(BakerReadBarrierKind::kGcRoot) |
+ BakerReadBarrierFirstRegField::Encode(root_reg) |
+ BakerReadBarrierSecondRegField::Encode(kInvalidEncodedReg);
+ }
+
explicit Thumb2RelativePatcher(RelativePatcherTargetProvider* provider);
void PatchCall(std::vector<uint8_t>* code,
@@ -45,6 +80,22 @@
uint32_t MaxNegativeDisplacement(ThunkType type) OVERRIDE;
private:
+ static constexpr uint32_t kInvalidEncodedReg = /* pc is invalid */ 15u;
+
+ static constexpr size_t kBitsForBakerReadBarrierKind =
+ MinimumBitsToStore(static_cast<size_t>(BakerReadBarrierKind::kLast));
+ static constexpr size_t kBitsForRegister = 4u;
+ using BakerReadBarrierKindField =
+ BitField<BakerReadBarrierKind, 0, kBitsForBakerReadBarrierKind>;
+ using BakerReadBarrierFirstRegField =
+ BitField<uint32_t, kBitsForBakerReadBarrierKind, kBitsForRegister>;
+ using BakerReadBarrierSecondRegField =
+ BitField<uint32_t, kBitsForBakerReadBarrierKind + kBitsForRegister, kBitsForRegister>;
+
+ static void CheckValidReg(uint32_t reg) {
+ DCHECK(reg < 12u && reg != kBakerCcEntrypointRegister);
+ }
+
void SetInsn32(std::vector<uint8_t>* code, uint32_t offset, uint32_t value);
static uint32_t GetInsn32(ArrayRef<const uint8_t> code, uint32_t offset);