[platform] Make NBitMask, Bit, and TestBit constexpr.
Also make NBitMask generic, replace uses of SignedNBitMask
with generic NBitMask, and remove SignedNBitMask.
TEST=No changes to functionality for existing callers, so existing tests.
Cq-Include-Trybots: luci.dart.try:vm-kernel-linux-release-simarm-try,vm-kernel-linux-release-simarm64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try
Change-Id: Ic33785e50be98123c75782c6e62ef32ec45f4191
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208181
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
diff --git a/runtime/platform/utils.h b/runtime/platform/utils.h
index a1d6b1b..84366eb 100644
--- a/runtime/platform/utils.h
+++ b/runtime/platform/utils.h
@@ -417,34 +417,26 @@
return ((-0x20000000000000LL <= value) && (value <= 0x20000000000000LL));
}
- static constexpr uword NBitMaskUnsafe(uint32_t n) {
- static_assert((sizeof(uword) * kBitsPerByte) == kBitsPerWord,
- "Unexpected uword size");
- return n == kBitsPerWord ? std::numeric_limits<uword>::max()
- : (static_cast<uword>(1) << n) - 1;
- }
-
// The lowest n bits are 1, the others are 0.
- static uword NBitMask(uint32_t n) {
- ASSERT(n <= kBitsPerWord);
- return NBitMaskUnsafe(n);
- }
-
- static word SignedNBitMask(uint32_t n) {
- uword mask = NBitMask(n);
- return bit_cast<word>(mask);
+ template <typename T = uword>
+ static constexpr T NBitMask(size_t n) {
+ using Unsigned = typename std::make_unsigned<T>::type;
+ constexpr size_t kBitsPerT = sizeof(T) * kBitsPerByte;
+ assert(n <= sizeof(T) * kBitsPerT);
+ return static_cast<T>(n == kBitsPerT ? std::numeric_limits<Unsigned>::max()
+ : (static_cast<Unsigned>(1) << n) - 1);
}
template <typename T = uword>
- static T Bit(uint32_t n) {
+ static constexpr T Bit(size_t n) {
ASSERT(n < sizeof(T) * kBitsPerByte);
T bit = 1;
return bit << n;
}
template <typename T>
- DART_FORCE_INLINE static bool TestBit(T mask, intptr_t position) {
- ASSERT(position < static_cast<intptr_t>(sizeof(T) * kBitsPerByte));
+ static constexpr bool TestBit(T mask, size_t position) {
+ ASSERT(position < sizeof(T) * kBitsPerByte);
return ((mask >> position) & 1) != 0;
}
diff --git a/runtime/vm/code_descriptors.h b/runtime/vm/code_descriptors.h
index 0d15c38..ac29be7 100644
--- a/runtime/vm/code_descriptors.h
+++ b/runtime/vm/code_descriptors.h
@@ -209,7 +209,7 @@
using ArgField = BitField<int32_t, int32_t, OpField::kNextBit>;
static constexpr int32_t kMaxArgValue =
- Utils::NBitMaskUnsafe(ArgField::bitsize() - 1);
+ Utils::NBitMask<int32_t>(ArgField::bitsize() - 1);
static constexpr int32_t kMinArgValue = ~kMaxArgValue;
static constexpr int32_t kSignBits = static_cast<uint32_t>(kMinArgValue) << 1;
};
diff --git a/runtime/vm/compiler/backend/il_arm.cc b/runtime/vm/compiler/backend/il_arm.cc
index 0c07ad2..5ede916 100644
--- a/runtime/vm/compiler/backend/il_arm.cc
+++ b/runtime/vm/compiler/backend/il_arm.cc
@@ -779,8 +779,8 @@
const intptr_t kCpuRegistersToPreserve =
kDartAvailableCpuRegs & ~kNonChangeableInputRegs;
const intptr_t kFpuRegistersToPreserve =
- Utils::SignedNBitMask(kNumberOfFpuRegisters) &
- ~(Utils::SignedNBitMask(kAbiPreservedFpuRegCount)
+ Utils::NBitMask<intptr_t>(kNumberOfFpuRegisters) &
+ ~(Utils::NBitMask<intptr_t>(kAbiPreservedFpuRegCount)
<< kAbiFirstPreservedFpuReg) &
~(1 << FpuTMP);
diff --git a/runtime/vm/compiler/backend/il_arm64.cc b/runtime/vm/compiler/backend/il_arm64.cc
index d8cebd7..9484c260 100644
--- a/runtime/vm/compiler/backend/il_arm64.cc
+++ b/runtime/vm/compiler/backend/il_arm64.cc
@@ -699,7 +699,7 @@
const intptr_t kCpuRegistersToPreserve =
kDartAvailableCpuRegs & ~kNonChangeableInputRegs;
const intptr_t kFpuRegistersToPreserve =
- Utils::SignedNBitMask(kNumberOfFpuRegisters) & ~(1l << FpuTMP);
+ Utils::NBitMask<intptr_t>(kNumberOfFpuRegisters) & ~(1l << FpuTMP);
const intptr_t kNumTemps = (Utils::CountOneBits64(kCpuRegistersToPreserve) +
Utils::CountOneBits64(kFpuRegistersToPreserve));
diff --git a/runtime/vm/v8_snapshot_writer.h b/runtime/vm/v8_snapshot_writer.h
index 644a2e0..c69abdc 100644
--- a/runtime/vm/v8_snapshot_writer.h
+++ b/runtime/vm/v8_snapshot_writer.h
@@ -58,7 +58,8 @@
private:
static constexpr size_t kIdSpaceBits =
Utils::BitLength(static_cast<int64_t>(IdSpace::kArtificial));
- static constexpr int64_t kIdSpaceMask = Utils::NBitMaskUnsafe(kIdSpaceBits);
+ static constexpr int64_t kIdSpaceMask =
+ Utils::NBitMask<int64_t>(kIdSpaceBits);
static const char* IdSpaceToCString(IdSpace space);
int64_t encoded_;
