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tint/utils: Manually inline HashmapBase::Scan() 

Clang was doing a poor job inlining this very hot function and its lambda argument.

Change-Id: Id2005b2ad131a1a1802bc7fb66085395b659ade2
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/116867
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
This commit is contained in:
Ben Clayton 2023-01-12 08:17:46 +00:00 committed by Dawn LUCI CQ
parent 973a685ad3
commit b607bfbddf
1 changed files with 42 additions and 75 deletions
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117
src/tint/utils/hashmap_base.h
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@ -291,24 +291,26 @@ class HashmapBase {
// Shuffle the entries backwards until we either find a free slot, or a slot that has zero
// distance.
Slot* prev = nullptr;
Scan(start, [&](size_t, size_t index) {
const auto count = slots_.Length();
for (size_t distance = 0, index = start; distance < count; distance++) {
auto& slot = slots_[index];
if (prev) {
// note: `distance == 0` also includes empty slots.
if (slot.distance == 0) {
// Clear the previous slot, and stop shuffling.
*prev = {};
return Action::kStop;
} else {
// Shuffle the slot backwards.
prev->entry = std::move(slot.entry);
prev->hash = slot.hash;
prev->distance = slot.distance - 1;
break;
}
// Shuffle the slot backwards.
prev->entry = std::move(slot.entry);
prev->hash = slot.hash;
prev->distance = slot.distance - 1;
}
prev = &slot;
return Action::kContinue;
});
index = (index == count - 1) ? 0 : index + 1;
}
// Entry was removed.
count_--;
@ -438,8 +440,8 @@ class HashmapBase {
}
};
PutResult result{};
Scan(hash.scan_start, [&](size_t distance, size_t index) {
const auto count = slots_.Length();
for (size_t distance = 0, index = hash.scan_start; distance < count; distance++) {
auto& slot = slots_[index];
if (!slot.entry.has_value()) {
// Found an empty slot.
@ -449,8 +451,7 @@ class HashmapBase {
slot.distance = distance;
count_++;
generation_++;
result = PutResult{MapAction::kAdded, ValueOf(*slot.entry)};
return Action::kStop;
return PutResult{MapAction::kAdded, ValueOf(*slot.entry)};
}
// Slot has an entry
@ -460,11 +461,10 @@ class HashmapBase {
if constexpr (MODE == PutMode::kReplace) {
slot.entry = make_entry();
generation_++;
result = PutResult{MapAction::kReplaced, ValueOf(*slot.entry)};
return PutResult{MapAction::kReplaced, ValueOf(*slot.entry)};
} else {
result = PutResult{MapAction::kKeptExisting, ValueOf(*slot.entry)};
return PutResult{MapAction::kKeptExisting, ValueOf(*slot.entry)};
}
return Action::kStop;
}
if (slot.distance < distance) {
@ -480,47 +480,15 @@ class HashmapBase {
count_++;
generation_++;
result = PutResult{MapAction::kAdded, ValueOf(*slot.entry)};
return Action::kStop;
return PutResult{MapAction::kAdded, ValueOf(*slot.entry)};
}
return Action::kContinue;
});
return result;
}
/// Return type of the Scan() callback.
enum class Action {
/// Continue scanning for a slot
kContinue,
/// Immediately stop scanning for a slot
kStop,
};
/// Sequentially visits each of the slots starting with the slot with the index @p start,
/// calling the callback function @p f for each slot until @p f returns Action::kStop.
/// @param start the index of the first slot to start scanning from.
/// @param f the callback function which:
/// * must be a function with the signature `Action(size_t distance, size_t index)`.
/// * must return Action::kStop within one whole cycle of the slots.
template <typename F>
void Scan(size_t start, F&& f) const {
size_t distance = 0;
for (size_t index = start; index < slots_.Length(); index++) {
if (f(distance, index) == Action::kStop) {
return;
}
distance++;
}
for (size_t index = 0; index < start; index++) {
if (f(distance, index) == Action::kStop) {
return;
}
distance++;
index = (index == count - 1) ? 0 : index + 1;
}
tint::diag::List diags;
TINT_ICE(Utils, diags) << "HashmapBase::Scan() looped entire map without finding a slot";
TINT_ICE(Utils, diags) << "HashmapBase::Put() looped entire map without finding a slot";
return PutResult{};
}
/// HashResult is the return value of Hash()
@ -546,45 +514,44 @@ class HashmapBase {
/// if found, the index of the slot that holds the key.
std::tuple<bool, size_t> IndexOf(const Key& key) const {
const auto hash = Hash(key);
bool found = false;
size_t idx = 0;
Scan(hash.scan_start, [&](size_t distance, size_t index) {
const auto count = slots_.Length();
for (size_t distance = 0, index = hash.scan_start; distance < count; distance++) {
auto& slot = slots_[index];
if (!slot.entry.has_value()) {
return Action::kStop;
return {/* found */ false, /* index */ 0};
}
if (slot.Equals(hash.code, key)) {
found = true;
idx = index;
return Action::kStop;
return {/* found */ true, index};
}
if (slot.distance < distance) {
// If the slot distance is less than the current probe distance, then the slot must
// be for entry that has an index that comes after key. In this situation, we know
// that the map does not contain the key, as it would have been found before this
// slot. The "Lookup" section of https://programming.guide/robin-hood-hashing.html
// suggests that the condition should inverted, but this is wrong.
return Action::kStop;
// If the slot distance is less than the current probe distance, then the slot
// must be for entry that has an index that comes after key. In this situation,
// we know that the map does not contain the key, as it would have been found
// before this slot. The "Lookup" section of
// https://programming.guide/robin-hood-hashing.html suggests that the condition
// should inverted, but this is wrong.
return {/* found */ false, /* index */ 0};
}
return Action::kContinue;
});
index = (index == count - 1) ? 0 : index + 1;
}
return {found, idx};
tint::diag::List diags;
TINT_ICE(Utils, diags) << "HashmapBase::IndexOf() looped entire map without finding a slot";
return {/* found */ false, /* index */ 0};
}
/// Shuffles slots for an insertion that has been placed one slot before `start`.
/// @param start the index of the first slot to start shuffling.
/// @param evicted the slot content that was evicted for the insertion.
void InsertShuffle(size_t start, Slot&& evicted) {
Scan(start, [&](size_t, size_t index) {
const auto count = slots_.Length();
for (size_t distance = 0, index = start; distance < count; distance++) {
auto& slot = slots_[index];
if (!slot.entry.has_value()) {
// Empty slot found for evicted.
slot = std::move(evicted);
return Action::kStop; // We're done.
return; // We're done.
}
if (slot.distance < evicted.distance) {
@ -596,8 +563,8 @@ class HashmapBase {
// evicted moves further from the target slot...
evicted.distance++;
return Action::kContinue;
});
index = (index == count - 1) ? 0 : index + 1;
}
}
/// @param count the number of new entries in the map