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Annotation page/length comparisons and helpers as const.
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These do not depend on observable state of the program, other than their
parameters.

PiperOrigin-RevId: 346169103
Change-Id: Ie918dfc0d823bc77443c5f6caae642cc2502346e
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@ckennelly @copybara-github
ckennelly authored and copybara-github committed Dec 7, 2020
1 parent 33ff976 commit bb86c5b
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Showing 3 changed files with 63 additions and 0 deletions.
27 changes: 27 additions & 0 deletions tcmalloc/huge_pages.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@

#include "tcmalloc/common.h"
#include "tcmalloc/internal/logging.h"
#include "tcmalloc/internal/optimization.h"
#include "tcmalloc/pages.h"

namespace tcmalloc {
Expand Down Expand Up @@ -83,13 +84,16 @@ struct HugeLength {

// Literal constructors (made explicit to avoid accidental uses when
// another unit was meant.)
TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength NHugePages(size_t n) { return HugeLength(n); }

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength HLFromBytes(size_t bytes) {
return NHugePages(bytes / kHugePageSize);
}

// Rounds *up* to the nearest hugepage.
TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength HLFromPages(Length pages) {
return NHugePages((pages + kPagesPerHugePage - Length(1)) /
kPagesPerHugePage);
Expand All @@ -116,58 +120,72 @@ inline constexpr bool operator<(HugeLength lhs, HugeLength rhs) {
return lhs.n < rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>(HugeLength lhs, HugeLength rhs) {
return lhs.n > rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<=(HugeLength lhs, HugeLength rhs) {
return lhs.n <= rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<(HugePage lhs, HugePage rhs) {
return lhs.pn < rhs.pn;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>(HugePage lhs, HugePage rhs) {
return lhs.pn > rhs.pn;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>=(HugeLength lhs, HugeLength rhs) {
return lhs.n >= rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<=(HugePage lhs, HugePage rhs) {
return lhs.pn <= rhs.pn;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>=(HugePage lhs, HugePage rhs) {
return lhs.pn >= rhs.pn;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator==(HugePage lhs, HugePage rhs) {
return lhs.pn == rhs.pn;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator!=(HugePage lhs, HugePage rhs) {
return !(lhs == rhs);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator==(HugeLength lhs, HugeLength rhs) {
return lhs.n == rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator!=(HugeLength lhs, HugeLength rhs) {
return lhs.n != rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr size_t operator/(HugeLength lhs, HugeLength rhs) {
return lhs.n / rhs.n;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength operator*(HugeLength lhs, size_t rhs) {
return NHugePages(lhs.n * rhs);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength operator/(HugeLength lhs, size_t rhs) {
return NHugePages(lhs.n / rhs);
}
Expand All @@ -177,23 +195,28 @@ inline HugeLength &operator*=(HugeLength &lhs, size_t rhs) {
return lhs;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength operator%(HugeLength lhs, HugeLength rhs) {
return NHugePages(lhs.n % rhs.n);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugePage operator+(HugePage lhs, HugeLength rhs) {
ASSERT(lhs.pn + rhs.n <= HugePage::kMaxPageNumber);
return HugePage{lhs.pn + rhs.n};
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugePage operator+(HugeLength lhs, HugePage rhs) {
return rhs + lhs;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugePage operator-(HugePage lhs, HugeLength rhs) {
return ASSERT(lhs.pn >= rhs.n), HugePage{lhs.pn - rhs.n};
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength operator-(HugePage lhs, HugePage rhs) {
return ASSERT(lhs.pn >= rhs.pn), NHugePages(lhs.pn - rhs.pn);
}
Expand All @@ -204,6 +227,7 @@ inline HugePage &operator+=(HugePage &lhs, HugeLength rhs) {
return lhs;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength operator+(HugeLength lhs, HugeLength rhs) {
return NHugePages(lhs.n + rhs.n);
}
Expand All @@ -213,6 +237,7 @@ inline HugeLength &operator+=(HugeLength &lhs, HugeLength rhs) {
return lhs;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr HugeLength operator-(HugeLength lhs, HugeLength rhs) {
return ASSERT(lhs.n >= rhs.n), NHugePages(lhs.n - rhs.n);
}
Expand All @@ -231,10 +256,12 @@ inline void PrintTo(const HugeLength &n, ::std::ostream *os) {
*os << n.raw_num() << "hps";
}

TCMALLOC_ATTRIBUTE_CONST
inline HugePage HugePageContaining(PageId p) {
return {p.index() >> (kHugePageShift - kPageShift)};
}

TCMALLOC_ATTRIBUTE_CONST
inline HugePage HugePageContaining(void *p) {
return HugePageContaining(PageIdContaining(p));
}
Expand Down
8 changes: 8 additions & 0 deletions tcmalloc/internal/optimization.h
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Original file line number Diff line number Diff line change
Expand Up @@ -34,4 +34,12 @@
#endif
#endif

// Annotations for functions that are not affected by nor affect observable
// state of the program.
#if ABSL_HAVE_ATTRIBUTE(const)
#define TCMALLOC_ATTRIBUTE_CONST __attribute__((const))
#else
#define TCMALLOC_ATTRIBUTE_CONST
#endif

#endif // TCMALLOC_INTERNAL_OPTIMIZATION_H_
28 changes: 28 additions & 0 deletions tcmalloc/pages.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
#include "absl/strings/string_view.h"
#include "tcmalloc/common.h"
#include "tcmalloc/internal/logging.h"
#include "tcmalloc/internal/optimization.h"

namespace tcmalloc {
namespace tcmalloc_internal {
Expand Down Expand Up @@ -142,17 +143,20 @@ class PageId {
uintptr_t pn_;
};

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length LengthFromBytes(size_t bytes) {
return Length(bytes >> kPageShift);
}

// Convert byte size into pages. This won't overflow, but may return
// an unreasonably large value if bytes is huge enough.
TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length BytesToLengthCeil(size_t bytes) {
return Length((bytes >> kPageShift) +
((bytes & (kPageSize - 1)) > 0 ? 1 : 0));
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length BytesToLengthFloor(size_t bytes) {
return Length(bytes >> kPageShift);
}
Expand All @@ -165,65 +169,82 @@ inline PageId& operator++(PageId& p) { // NOLINT(runtime/references)
return p += Length(1);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<(PageId lhs, PageId rhs) {
return lhs.pn_ < rhs.pn_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>(PageId lhs, PageId rhs) {
return lhs.pn_ > rhs.pn_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<=(PageId lhs, PageId rhs) {
return lhs.pn_ <= rhs.pn_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>=(PageId lhs, PageId rhs) {
return lhs.pn_ >= rhs.pn_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator==(PageId lhs, PageId rhs) {
return lhs.pn_ == rhs.pn_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator!=(PageId lhs, PageId rhs) {
return lhs.pn_ != rhs.pn_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr PageId operator+(PageId lhs, Length rhs) { return lhs += rhs; }

TCMALLOC_ATTRIBUTE_CONST
inline constexpr PageId operator+(Length lhs, PageId rhs) { return rhs += lhs; }

TCMALLOC_ATTRIBUTE_CONST
inline constexpr PageId operator-(PageId lhs, Length rhs) { return lhs -= rhs; }

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator-(PageId lhs, PageId rhs) {
ASSERT(lhs.pn_ >= rhs.pn_);
return Length(lhs.pn_ - rhs.pn_);
}

TCMALLOC_ATTRIBUTE_CONST
inline PageId PageIdContaining(const void* p) {
return PageId(reinterpret_cast<uintptr_t>(p) >> kPageShift);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<(Length lhs, Length rhs) {
return lhs.n_ < rhs.n_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>(Length lhs, Length rhs) {
return lhs.n_ > rhs.n_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator<=(Length lhs, Length rhs) {
return lhs.n_ <= rhs.n_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator>=(Length lhs, Length rhs) {
return lhs.n_ >= rhs.n_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator==(Length lhs, Length rhs) {
return lhs.n_ == rhs.n_;
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr bool operator!=(Length lhs, Length rhs) {
return lhs.n_ != rhs.n_;
}
Expand All @@ -232,31 +253,38 @@ inline Length& operator++(Length& l) { return l += Length(1); }

inline Length& operator--(Length& l) { return l -= Length(1); }

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator+(Length lhs, Length rhs) {
return Length(lhs.raw_num() + rhs.raw_num());
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator-(Length lhs, Length rhs) {
return Length(lhs.raw_num() - rhs.raw_num());
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator*(Length lhs, size_t rhs) {
return Length(lhs.raw_num() * rhs);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator*(size_t lhs, Length rhs) {
return Length(lhs * rhs.raw_num());
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr size_t operator/(Length lhs, Length rhs) {
return lhs.raw_num() / rhs.raw_num();
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator/(Length lhs, size_t rhs) {
ASSERT(rhs != 0);
return Length(lhs.raw_num() / rhs);
}

TCMALLOC_ATTRIBUTE_CONST
inline constexpr Length operator%(Length lhs, Length rhs) {
ASSERT(rhs.raw_num() != 0);
return Length(lhs.raw_num() % rhs.raw_num());
Expand Down

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