Get rid of tail padding within `absl::Duration`. This reduces memory usage needs when storing duration in containers (e.g. `vector<absl::Duration>` uses 25% less memory), and allows classes with `absl::Duration` fields to fit other stuff in memory previously used by tail padding (e.g. `std::optional<absl::Duration>` is now 16 bytes instead of 24).

PiperOrigin-RevId: 506568782
Change-Id: Ic9e077f02a80da013fb2d312aff77761b970c07a

1 files changed, 17 insertions, 22 deletions

diff --git a/absl/time/duration.cc b/absl/time/duration.cc
index b915d749..911e80f8 100644
--- a/absl/time/duration.cc
+++ b/absl/time/duration.cc
@@ -407,18 +407,16 @@ int64_t IDivDuration(bool satq, const Duration num, const Duration den,
 Duration& Duration::operator+=(Duration rhs) {
   if (time_internal::IsInfiniteDuration(*this)) return *this;
   if (time_internal::IsInfiniteDuration(rhs)) return *this = rhs;
-  const int64_t orig_rep_hi = rep_hi_.Get();
-  rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_.Get()) +
-                           EncodeTwosComp(rhs.rep_hi_.Get()));
+  const int64_t orig_rep_hi = rep_hi_;
+  rep_hi_ =
+      DecodeTwosComp(EncodeTwosComp(rep_hi_) + EncodeTwosComp(rhs.rep_hi_));
   if (rep_lo_ >= kTicksPerSecond - rhs.rep_lo_) {
-    rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_.Get()) + 1);
+    rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_) + 1);
     rep_lo_ -= kTicksPerSecond;
   }
   rep_lo_ += rhs.rep_lo_;
-  if (rhs.rep_hi_.Get() < 0 ? rep_hi_.Get() > orig_rep_hi
-                            : rep_hi_.Get() < orig_rep_hi) {
-    return *this =
-               rhs.rep_hi_.Get() < 0 ? -InfiniteDuration() : InfiniteDuration();
+  if (rhs.rep_hi_ < 0 ? rep_hi_ > orig_rep_hi : rep_hi_ < orig_rep_hi) {
+    return *this = rhs.rep_hi_ < 0 ? -InfiniteDuration() : InfiniteDuration();
   }
   return *this;
 }
@@ -426,21 +424,18 @@ Duration& Duration::operator+=(Duration rhs) {
 Duration& Duration::operator-=(Duration rhs) {
   if (time_internal::IsInfiniteDuration(*this)) return *this;
   if (time_internal::IsInfiniteDuration(rhs)) {
-    return *this = rhs.rep_hi_.Get() >= 0 ? -InfiniteDuration()
-                                          : InfiniteDuration();
+    return *this = rhs.rep_hi_ >= 0 ? -InfiniteDuration() : InfiniteDuration();
   }
-  const int64_t orig_rep_hi = rep_hi_.Get();
-  rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_.Get()) -
-                           EncodeTwosComp(rhs.rep_hi_.Get()));
+  const int64_t orig_rep_hi = rep_hi_;
+  rep_hi_ =
+      DecodeTwosComp(EncodeTwosComp(rep_hi_) - EncodeTwosComp(rhs.rep_hi_));
   if (rep_lo_ < rhs.rep_lo_) {
-    rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_.Get()) - 1);
+    rep_hi_ = DecodeTwosComp(EncodeTwosComp(rep_hi_) - 1);
     rep_lo_ += kTicksPerSecond;
   }
   rep_lo_ -= rhs.rep_lo_;
-  if (rhs.rep_hi_.Get() < 0 ? rep_hi_.Get() < orig_rep_hi
-                            : rep_hi_.Get() > orig_rep_hi) {
-    return *this = rhs.rep_hi_.Get() >= 0 ? -InfiniteDuration()
-                                          : InfiniteDuration();
+  if (rhs.rep_hi_ < 0 ? rep_hi_ < orig_rep_hi : rep_hi_ > orig_rep_hi) {
+    return *this = rhs.rep_hi_ >= 0 ? -InfiniteDuration() : InfiniteDuration();
   }
   return *this;
 }
@@ -451,7 +446,7 @@ Duration& Duration::operator-=(Duration rhs) {
 
 Duration& Duration::operator*=(int64_t r) {
   if (time_internal::IsInfiniteDuration(*this)) {
-    const bool is_neg = (r < 0) != (rep_hi_.Get() < 0);
+    const bool is_neg = (r < 0) != (rep_hi_ < 0);
     return *this = is_neg ? -InfiniteDuration() : InfiniteDuration();
   }
   return *this = ScaleFixed<SafeMultiply>(*this, r);
@@ -459,7 +454,7 @@ Duration& Duration::operator*=(int64_t r) {
 
 Duration& Duration::operator*=(double r) {
   if (time_internal::IsInfiniteDuration(*this) || !IsFinite(r)) {
-    const bool is_neg = std::signbit(r) != (rep_hi_.Get() < 0);
+    const bool is_neg = (std::signbit(r) != 0) != (rep_hi_ < 0);
     return *this = is_neg ? -InfiniteDuration() : InfiniteDuration();
   }
   return *this = ScaleDouble<std::multiplies>(*this, r);
@@ -467,7 +462,7 @@ Duration& Duration::operator*=(double r) {
 
 Duration& Duration::operator/=(int64_t r) {
   if (time_internal::IsInfiniteDuration(*this) || r == 0) {
-    const bool is_neg = (r < 0) != (rep_hi_.Get() < 0);
+    const bool is_neg = (r < 0) != (rep_hi_ < 0);
     return *this = is_neg ? -InfiniteDuration() : InfiniteDuration();
   }
   return *this = ScaleFixed<std::divides>(*this, r);
@@ -475,7 +470,7 @@ Duration& Duration::operator/=(int64_t r) {
 
 Duration& Duration::operator/=(double r) {
   if (time_internal::IsInfiniteDuration(*this) || !IsValidDivisor(r)) {
-    const bool is_neg = std::signbit(r) != (rep_hi_.Get() < 0);
+    const bool is_neg = (std::signbit(r) != 0) != (rep_hi_ < 0);
     return *this = is_neg ? -InfiniteDuration() : InfiniteDuration();
   }
   return *this = ScaleDouble<std::divides>(*this, r);