ART: Clean up arm64 kNumberOfXRegisters usage.
Avoid undefined behavior for arm64 stemming from 1u << 32 in
loops with upper bound kNumberOfXRegisters.
Create iterators for enumerating bits in an integer either
from high to low or from low to high and use them for
<arch>Context::FillCalleeSaves() on all architectures.
Refactor runtime/utils.{h,cc} by moving all bit-fiddling
functions to runtime/base/bit_utils.{h,cc} (together with
the new bit iterators) and all time-related functions to
runtime/base/time_utils.{h,cc}. Improve test coverage and
fix some corner cases for the bit-fiddling functions.
Bug: 13925192
Change-Id: I704884dab15b41ecf7a1c47d397ab1c3fc7ee0f7
diff --git a/runtime/arch/arm/context_arm.cc b/runtime/arch/arm/context_arm.cc
index 5bd23d0..c0e658c 100644
--- a/runtime/arch/arm/context_arm.cc
+++ b/runtime/arch/arm/context_arm.cc
@@ -16,9 +16,9 @@
#include "context_arm.h"
+#include "base/bit_utils.h"
#include "mirror/art_method-inl.h"
#include "quick/quick_method_frame_info.h"
-#include "utils.h"
namespace art {
namespace arm {
@@ -26,12 +26,8 @@
static constexpr uint32_t gZero = 0;
void ArmContext::Reset() {
- for (size_t i = 0; i < kNumberOfCoreRegisters; i++) {
- gprs_[i] = nullptr;
- }
- for (size_t i = 0; i < kNumberOfSRegisters; i++) {
- fprs_[i] = nullptr;
- }
+ std::fill_n(gprs_, arraysize(gprs_), nullptr);
+ std::fill_n(fprs_, arraysize(fprs_), nullptr);
gprs_[SP] = &sp_;
gprs_[PC] = &pc_;
// Initialize registers with easy to spot debug values.
@@ -42,29 +38,23 @@
void ArmContext::FillCalleeSaves(const StackVisitor& fr) {
mirror::ArtMethod* method = fr.GetMethod();
const QuickMethodFrameInfo frame_info = method->GetQuickFrameInfo();
- size_t spill_count = POPCOUNT(frame_info.CoreSpillMask());
- size_t fp_spill_count = POPCOUNT(frame_info.FpSpillMask());
- if (spill_count > 0) {
- // Lowest number spill is farthest away, walk registers and fill into context
- int j = 1;
- for (size_t i = 0; i < kNumberOfCoreRegisters; i++) {
- if (((frame_info.CoreSpillMask() >> i) & 1) != 0) {
- gprs_[i] = fr.CalleeSaveAddress(spill_count - j, frame_info.FrameSizeInBytes());
- j++;
- }
- }
+ int spill_pos = 0;
+
+ // Core registers come first, from the highest down to the lowest.
+ uint32_t core_regs = frame_info.CoreSpillMask();
+ DCHECK_EQ(0u, core_regs & (static_cast<uint32_t>(-1) << kNumberOfCoreRegisters));
+ for (uint32_t core_reg : HighToLowBits(core_regs)) {
+ gprs_[core_reg] = fr.CalleeSaveAddress(spill_pos, frame_info.FrameSizeInBytes());
+ ++spill_pos;
}
- if (fp_spill_count > 0) {
- // Lowest number spill is farthest away, walk registers and fill into context
- int j = 1;
- for (size_t i = 0; i < kNumberOfSRegisters; i++) {
- if (((frame_info.FpSpillMask() >> i) & 1) != 0) {
- fprs_[i] = fr.CalleeSaveAddress(spill_count + fp_spill_count - j,
- frame_info.FrameSizeInBytes());
- j++;
- }
- }
+ DCHECK_EQ(spill_pos, POPCOUNT(frame_info.CoreSpillMask()));
+
+ // FP registers come second, from the highest down to the lowest.
+ for (uint32_t fp_reg : HighToLowBits(frame_info.FpSpillMask())) {
+ fprs_[fp_reg] = fr.CalleeSaveAddress(spill_pos, frame_info.FrameSizeInBytes());
+ ++spill_pos;
}
+ DCHECK_EQ(spill_pos, POPCOUNT(frame_info.CoreSpillMask()) + POPCOUNT(frame_info.FpSpillMask()));
}
void ArmContext::SetGPR(uint32_t reg, uintptr_t value) {
diff --git a/runtime/arch/arm/quick_method_frame_info_arm.h b/runtime/arch/arm/quick_method_frame_info_arm.h
index c1f3fc2..5580ee4 100644
--- a/runtime/arch/arm/quick_method_frame_info_arm.h
+++ b/runtime/arch/arm/quick_method_frame_info_arm.h
@@ -17,10 +17,10 @@
#ifndef ART_RUNTIME_ARCH_ARM_QUICK_METHOD_FRAME_INFO_ARM_H_
#define ART_RUNTIME_ARCH_ARM_QUICK_METHOD_FRAME_INFO_ARM_H_
+#include "base/bit_utils.h"
#include "quick/quick_method_frame_info.h"
#include "registers_arm.h"
#include "runtime.h" // for Runtime::CalleeSaveType.
-#include "utils.h"
namespace art {
namespace arm {