[llvm-branch-commits] [llvm] [NFC][MemProf] Move Radix tree methods to their own header and cpp. (PR #140501)
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llvm-branch-commits at lists.llvm.org
Mon May 19 00:09:46 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-pgo
Author: Snehasish Kumar (snehasish)
<details>
<summary>Changes</summary>
---
Patch is 53.29 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/140501.diff
11 Files Affected:
- (modified) llvm/include/llvm/ProfileData/MemProf.h (-336)
- (added) llvm/include/llvm/ProfileData/MemProfRadixTree.h (+358)
- (modified) llvm/include/llvm/ProfileData/MemProfReader.h (+1-1)
- (modified) llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (+1)
- (modified) llvm/lib/ProfileData/CMakeLists.txt (+1)
- (modified) llvm/lib/ProfileData/IndexedMemProfData.cpp (+1)
- (modified) llvm/lib/ProfileData/InstrProfReader.cpp (+2-1)
- (modified) llvm/lib/ProfileData/MemProf.cpp (-235)
- (added) llvm/lib/ProfileData/MemProfRadixTree.cpp (+253)
- (modified) llvm/unittests/ProfileData/InstrProfTest.cpp (+1)
- (modified) llvm/unittests/ProfileData/MemProfTest.cpp (+2-1)
``````````diff
diff --git a/llvm/include/llvm/ProfileData/MemProf.h b/llvm/include/llvm/ProfileData/MemProf.h
index e713c3807611b..0bc1432f7d198 100644
--- a/llvm/include/llvm/ProfileData/MemProf.h
+++ b/llvm/include/llvm/ProfileData/MemProf.h
@@ -818,133 +818,6 @@ class CallStackLookupTrait {
}
};
-namespace detail {
-// "Dereference" the iterator from DenseMap or OnDiskChainedHashTable. We have
-// to do so in one of two different ways depending on the type of the hash
-// table.
-template <typename value_type, typename IterTy>
-value_type DerefIterator(IterTy Iter) {
- using deref_type = llvm::remove_cvref_t<decltype(*Iter)>;
- if constexpr (std::is_same_v<deref_type, value_type>)
- return *Iter;
- else
- return Iter->second;
-}
-} // namespace detail
-
-// A function object that returns a frame for a given FrameId.
-template <typename MapTy> struct FrameIdConverter {
- std::optional<FrameId> LastUnmappedId;
- MapTy ⤅
-
- FrameIdConverter() = delete;
- FrameIdConverter(MapTy &Map) : Map(Map) {}
-
- // Delete the copy constructor and copy assignment operator to avoid a
- // situation where a copy of FrameIdConverter gets an error in LastUnmappedId
- // while the original instance doesn't.
- FrameIdConverter(const FrameIdConverter &) = delete;
- FrameIdConverter &operator=(const FrameIdConverter &) = delete;
-
- Frame operator()(FrameId Id) {
- auto Iter = Map.find(Id);
- if (Iter == Map.end()) {
- LastUnmappedId = Id;
- return Frame();
- }
- return detail::DerefIterator<Frame>(Iter);
- }
-};
-
-// A function object that returns a call stack for a given CallStackId.
-template <typename MapTy> struct CallStackIdConverter {
- std::optional<CallStackId> LastUnmappedId;
- MapTy ⤅
- llvm::function_ref<Frame(FrameId)> FrameIdToFrame;
-
- CallStackIdConverter() = delete;
- CallStackIdConverter(MapTy &Map,
- llvm::function_ref<Frame(FrameId)> FrameIdToFrame)
- : Map(Map), FrameIdToFrame(FrameIdToFrame) {}
-
- // Delete the copy constructor and copy assignment operator to avoid a
- // situation where a copy of CallStackIdConverter gets an error in
- // LastUnmappedId while the original instance doesn't.
- CallStackIdConverter(const CallStackIdConverter &) = delete;
- CallStackIdConverter &operator=(const CallStackIdConverter &) = delete;
-
- std::vector<Frame> operator()(CallStackId CSId) {
- std::vector<Frame> Frames;
- auto CSIter = Map.find(CSId);
- if (CSIter == Map.end()) {
- LastUnmappedId = CSId;
- } else {
- llvm::SmallVector<FrameId> CS =
- detail::DerefIterator<llvm::SmallVector<FrameId>>(CSIter);
- Frames.reserve(CS.size());
- for (FrameId Id : CS)
- Frames.push_back(FrameIdToFrame(Id));
- }
- return Frames;
- }
-};
-
-// A function object that returns a Frame stored at a given index into the Frame
-// array in the profile.
-struct LinearFrameIdConverter {
- const unsigned char *FrameBase;
-
- LinearFrameIdConverter() = delete;
- LinearFrameIdConverter(const unsigned char *FrameBase)
- : FrameBase(FrameBase) {}
-
- Frame operator()(LinearFrameId LinearId) {
- uint64_t Offset = static_cast<uint64_t>(LinearId) * Frame::serializedSize();
- return Frame::deserialize(FrameBase + Offset);
- }
-};
-
-// A function object that returns a call stack stored at a given index into the
-// call stack array in the profile.
-struct LinearCallStackIdConverter {
- const unsigned char *CallStackBase;
- llvm::function_ref<Frame(LinearFrameId)> FrameIdToFrame;
-
- LinearCallStackIdConverter() = delete;
- LinearCallStackIdConverter(
- const unsigned char *CallStackBase,
- llvm::function_ref<Frame(LinearFrameId)> FrameIdToFrame)
- : CallStackBase(CallStackBase), FrameIdToFrame(FrameIdToFrame) {}
-
- std::vector<Frame> operator()(LinearCallStackId LinearCSId) {
- std::vector<Frame> Frames;
-
- const unsigned char *Ptr =
- CallStackBase +
- static_cast<uint64_t>(LinearCSId) * sizeof(LinearFrameId);
- uint32_t NumFrames =
- support::endian::readNext<uint32_t, llvm::endianness::little>(Ptr);
- Frames.reserve(NumFrames);
- for (; NumFrames; --NumFrames) {
- LinearFrameId Elem =
- support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
- // Follow a pointer to the parent, if any. See comments below on
- // CallStackRadixTreeBuilder for the description of the radix tree format.
- if (static_cast<std::make_signed_t<LinearFrameId>>(Elem) < 0) {
- Ptr += (-Elem) * sizeof(LinearFrameId);
- Elem =
- support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
- }
- // We shouldn't encounter another pointer.
- assert(static_cast<std::make_signed_t<LinearFrameId>>(Elem) >= 0);
- Frames.push_back(FrameIdToFrame(Elem));
- Ptr += sizeof(LinearFrameId);
- }
-
- return Frames;
- }
-};
-
struct LineLocation {
LineLocation(uint32_t L, uint32_t D) : LineOffset(L), Column(D) {}
@@ -970,73 +843,6 @@ struct LineLocation {
// A pair of a call site location and its corresponding callee GUID.
using CallEdgeTy = std::pair<LineLocation, uint64_t>;
-// Used to extract caller-callee pairs from the call stack array. The leaf
-// frame is assumed to call a heap allocation function with GUID 0. The
-// resulting pairs are accumulated in CallerCalleePairs. Users can take it
-// with:
-//
-// auto Pairs = std::move(Extractor.CallerCalleePairs);
-struct CallerCalleePairExtractor {
- // The base address of the radix tree array.
- const unsigned char *CallStackBase;
- // A functor to convert a linear FrameId to a Frame.
- llvm::function_ref<Frame(LinearFrameId)> FrameIdToFrame;
- // A map from caller GUIDs to lists of call sites in respective callers.
- DenseMap<uint64_t, SmallVector<CallEdgeTy, 0>> CallerCalleePairs;
-
- // The set of linear call stack IDs that we've visited.
- BitVector Visited;
-
- CallerCalleePairExtractor() = delete;
- CallerCalleePairExtractor(
- const unsigned char *CallStackBase,
- llvm::function_ref<Frame(LinearFrameId)> FrameIdToFrame,
- unsigned RadixTreeSize)
- : CallStackBase(CallStackBase), FrameIdToFrame(FrameIdToFrame),
- Visited(RadixTreeSize) {}
-
- void operator()(LinearCallStackId LinearCSId) {
- const unsigned char *Ptr =
- CallStackBase +
- static_cast<uint64_t>(LinearCSId) * sizeof(LinearFrameId);
- uint32_t NumFrames =
- support::endian::readNext<uint32_t, llvm::endianness::little>(Ptr);
- // The leaf frame calls a function with GUID 0.
- uint64_t CalleeGUID = 0;
- for (; NumFrames; --NumFrames) {
- LinearFrameId Elem =
- support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
- // Follow a pointer to the parent, if any. See comments below on
- // CallStackRadixTreeBuilder for the description of the radix tree format.
- if (static_cast<std::make_signed_t<LinearFrameId>>(Elem) < 0) {
- Ptr += (-Elem) * sizeof(LinearFrameId);
- Elem =
- support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
- }
- // We shouldn't encounter another pointer.
- assert(static_cast<std::make_signed_t<LinearFrameId>>(Elem) >= 0);
-
- // Add a new caller-callee pair.
- Frame F = FrameIdToFrame(Elem);
- uint64_t CallerGUID = F.Function;
- LineLocation Loc(F.LineOffset, F.Column);
- CallerCalleePairs[CallerGUID].emplace_back(Loc, CalleeGUID);
-
- // Keep track of the indices we've visited. If we've already visited the
- // current one, terminate the traversal. We will not discover any new
- // caller-callee pair by continuing the traversal.
- unsigned Offset =
- std::distance(CallStackBase, Ptr) / sizeof(LinearFrameId);
- if (Visited.test(Offset))
- break;
- Visited.set(Offset);
-
- Ptr += sizeof(LinearFrameId);
- CalleeGUID = CallerGUID;
- }
- }
-};
-
struct IndexedMemProfData {
// A map to hold memprof data per function. The lower 64 bits obtained from
// the md5 hash of the function name is used to index into the map.
@@ -1087,148 +893,6 @@ struct IndexedMemProfData {
// Compute a CallStackId for a given call stack.
CallStackId hashCallStack(ArrayRef<FrameId> CS) const;
};
-
-// A convenience wrapper around FrameIdConverter and CallStackIdConverter for
-// tests.
-struct IndexedCallstackIdConverter {
- IndexedCallstackIdConverter() = delete;
- IndexedCallstackIdConverter(IndexedMemProfData &MemProfData)
- : FrameIdConv(MemProfData.Frames),
- CSIdConv(MemProfData.CallStacks, FrameIdConv) {}
-
- // Delete the copy constructor and copy assignment operator to avoid a
- // situation where a copy of IndexedCallstackIdConverter gets an error in
- // LastUnmappedId while the original instance doesn't.
- IndexedCallstackIdConverter(const IndexedCallstackIdConverter &) = delete;
- IndexedCallstackIdConverter &
- operator=(const IndexedCallstackIdConverter &) = delete;
-
- std::vector<Frame> operator()(CallStackId CSId) { return CSIdConv(CSId); }
-
- FrameIdConverter<decltype(IndexedMemProfData::Frames)> FrameIdConv;
- CallStackIdConverter<decltype(IndexedMemProfData::CallStacks)> CSIdConv;
-};
-
-struct FrameStat {
- // The number of occurrences of a given FrameId.
- uint64_t Count = 0;
- // The sum of indexes where a given FrameId shows up.
- uint64_t PositionSum = 0;
-};
-
-// Compute a histogram of Frames in call stacks.
-template <typename FrameIdTy>
-llvm::DenseMap<FrameIdTy, FrameStat>
-computeFrameHistogram(llvm::MapVector<CallStackId, llvm::SmallVector<FrameIdTy>>
- &MemProfCallStackData);
-
-// Construct a radix tree of call stacks.
-//
-// A set of call stacks might look like:
-//
-// CallStackId 1: f1 -> f2 -> f3
-// CallStackId 2: f1 -> f2 -> f4 -> f5
-// CallStackId 3: f1 -> f2 -> f4 -> f6
-// CallStackId 4: f7 -> f8 -> f9
-//
-// where each fn refers to a stack frame.
-//
-// Since we expect a lot of common prefixes, we can compress the call stacks
-// into a radix tree like:
-//
-// CallStackId 1: f1 -> f2 -> f3
-// |
-// CallStackId 2: +---> f4 -> f5
-// |
-// CallStackId 3: +---> f6
-//
-// CallStackId 4: f7 -> f8 -> f9
-//
-// Now, we are interested in retrieving call stacks for a given CallStackId, so
-// we just need a pointer from a given call stack to its parent. For example,
-// CallStackId 2 would point to CallStackId 1 as a parent.
-//
-// We serialize the radix tree above into a single array along with the length
-// of each call stack and pointers to the parent call stacks.
-//
-// Index: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
-// Array: L3 f9 f8 f7 L4 f6 J3 L4 f5 f4 J3 L3 f3 f2 f1
-// ^ ^ ^ ^
-// | | | |
-// CallStackId 4: 0 --+ | | |
-// CallStackId 3: 4 --------------+ | |
-// CallStackId 2: 7 -----------------------+ |
-// CallStackId 1: 11 -----------------------------------+
-//
-// - LN indicates the length of a call stack, encoded as ordinary integer N.
-//
-// - JN indicates a pointer to the parent, encoded as -N.
-//
-// The radix tree allows us to reconstruct call stacks in the leaf-to-root
-// order as we scan the array from left ro right while following pointers to
-// parents along the way.
-//
-// For example, if we are decoding CallStackId 2, we start a forward traversal
-// at Index 7, noting the call stack length of 4 and obtaining f5 and f4. When
-// we see J3 at Index 10, we resume a forward traversal at Index 13 = 10 + 3,
-// picking up f2 and f1. We are done after collecting 4 frames as indicated at
-// the beginning of the traversal.
-//
-// On-disk IndexedMemProfRecord will refer to call stacks by their indexes into
-// the radix tree array, so we do not explicitly encode mappings like:
-// "CallStackId 1 -> 11".
-template <typename FrameIdTy> class CallStackRadixTreeBuilder {
- // The radix tree array.
- std::vector<LinearFrameId> RadixArray;
-
- // Mapping from CallStackIds to indexes into RadixArray.
- llvm::DenseMap<CallStackId, LinearCallStackId> CallStackPos;
-
- // In build, we partition a given call stack into two parts -- the prefix
- // that's common with the previously encoded call stack and the frames beyond
- // the common prefix -- the unique portion. Then we want to find out where
- // the common prefix is stored in RadixArray so that we can link the unique
- // portion to the common prefix. Indexes, declared below, helps with our
- // needs. Intuitively, Indexes tells us where each of the previously encoded
- // call stack is stored in RadixArray. More formally, Indexes satisfies:
- //
- // RadixArray[Indexes[I]] == Prev[I]
- //
- // for every I, where Prev is the the call stack in the root-to-leaf order
- // previously encoded by build. (Note that Prev, as passed to
- // encodeCallStack, is in the leaf-to-root order.)
- //
- // For example, if the call stack being encoded shares 5 frames at the root of
- // the call stack with the previously encoded call stack,
- // RadixArray[Indexes[0]] is the root frame of the common prefix.
- // RadixArray[Indexes[5 - 1]] is the last frame of the common prefix.
- std::vector<LinearCallStackId> Indexes;
-
- using CSIdPair = std::pair<CallStackId, llvm::SmallVector<FrameIdTy>>;
-
- // Encode a call stack into RadixArray. Return the starting index within
- // RadixArray.
- LinearCallStackId encodeCallStack(
- const llvm::SmallVector<FrameIdTy> *CallStack,
- const llvm::SmallVector<FrameIdTy> *Prev,
- const llvm::DenseMap<FrameIdTy, LinearFrameId> *MemProfFrameIndexes);
-
-public:
- CallStackRadixTreeBuilder() = default;
-
- // Build a radix tree array.
- void
- build(llvm::MapVector<CallStackId, llvm::SmallVector<FrameIdTy>>
- &&MemProfCallStackData,
- const llvm::DenseMap<FrameIdTy, LinearFrameId> *MemProfFrameIndexes,
- llvm::DenseMap<FrameIdTy, FrameStat> &FrameHistogram);
-
- ArrayRef<LinearFrameId> getRadixArray() const { return RadixArray; }
-
- llvm::DenseMap<CallStackId, LinearCallStackId> takeCallStackPos() {
- return std::move(CallStackPos);
- }
-};
} // namespace memprof
} // namespace llvm
diff --git a/llvm/include/llvm/ProfileData/MemProfRadixTree.h b/llvm/include/llvm/ProfileData/MemProfRadixTree.h
new file mode 100644
index 0000000000000..9abf9f7a8774b
--- /dev/null
+++ b/llvm/include/llvm/ProfileData/MemProfRadixTree.h
@@ -0,0 +1,358 @@
+//===- MemProfRadixTree.h - MemProf format support ------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// A custom Radix Tree builder for memprof data to optimize for space.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_PROFILEDATA_MEMPROFRADIXTREE_H
+#define LLVM_PROFILEDATA_MEMPROFRADIXTREE_H
+
+#include "llvm/ProfileData/MemProf.h"
+
+namespace llvm {
+namespace memprof {
+namespace detail {
+// "Dereference" the iterator from DenseMap or OnDiskChainedHashTable. We have
+// to do so in one of two different ways depending on the type of the hash
+// table.
+template <typename value_type, typename IterTy>
+value_type DerefIterator(IterTy Iter) {
+ using deref_type = llvm::remove_cvref_t<decltype(*Iter)>;
+ if constexpr (std::is_same_v<deref_type, value_type>)
+ return *Iter;
+ else
+ return Iter->second;
+}
+} // namespace detail
+
+// A function object that returns a frame for a given FrameId.
+template <typename MapTy> struct FrameIdConverter {
+ std::optional<FrameId> LastUnmappedId;
+ MapTy ⤅
+
+ FrameIdConverter() = delete;
+ FrameIdConverter(MapTy &Map) : Map(Map) {}
+
+ // Delete the copy constructor and copy assignment operator to avoid a
+ // situation where a copy of FrameIdConverter gets an error in LastUnmappedId
+ // while the original instance doesn't.
+ FrameIdConverter(const FrameIdConverter &) = delete;
+ FrameIdConverter &operator=(const FrameIdConverter &) = delete;
+
+ Frame operator()(FrameId Id) {
+ auto Iter = Map.find(Id);
+ if (Iter == Map.end()) {
+ LastUnmappedId = Id;
+ return Frame();
+ }
+ return detail::DerefIterator<Frame>(Iter);
+ }
+};
+
+// A function object that returns a call stack for a given CallStackId.
+template <typename MapTy> struct CallStackIdConverter {
+ std::optional<CallStackId> LastUnmappedId;
+ MapTy ⤅
+ llvm::function_ref<Frame(FrameId)> FrameIdToFrame;
+
+ CallStackIdConverter() = delete;
+ CallStackIdConverter(MapTy &Map,
+ llvm::function_ref<Frame(FrameId)> FrameIdToFrame)
+ : Map(Map), FrameIdToFrame(FrameIdToFrame) {}
+
+ // Delete the copy constructor and copy assignment operator to avoid a
+ // situation where a copy of CallStackIdConverter gets an error in
+ // LastUnmappedId while the original instance doesn't.
+ CallStackIdConverter(const CallStackIdConverter &) = delete;
+ CallStackIdConverter &operator=(const CallStackIdConverter &) = delete;
+
+ std::vector<Frame> operator()(CallStackId CSId) {
+ std::vector<Frame> Frames;
+ auto CSIter = Map.find(CSId);
+ if (CSIter == Map.end()) {
+ LastUnmappedId = CSId;
+ } else {
+ llvm::SmallVector<FrameId> CS =
+ detail::DerefIterator<llvm::SmallVector<FrameId>>(CSIter);
+ Frames.reserve(CS.size());
+ for (FrameId Id : CS)
+ Frames.push_back(FrameIdToFrame(Id));
+ }
+ return Frames;
+ }
+};
+
+// A function object that returns a Frame stored at a given index into the Frame
+// array in the profile.
+struct LinearFrameIdConverter {
+ const unsigned char *FrameBase;
+
+ LinearFrameIdConverter() = delete;
+ LinearFrameIdConverter(const unsigned char *FrameBase)
+ : FrameBase(FrameBase) {}
+
+ Frame operator()(LinearFrameId LinearId) {
+ uint64_t Offset = static_cast<uint64_t>(LinearId) * Frame::serializedSize();
+ return Frame::deserialize(FrameBase + Offset);
+ }
+};
+
+// A function object that returns a call stack stored at a given index into the
+// call stack array in the profile.
+struct LinearCallStackIdConverter {
+ const unsigned char *CallStackBase;
+ llvm::function_ref<Frame(LinearFrameId)> FrameIdToFrame;
+
+ LinearCallStackIdConverter() = delete;
+ LinearCallStackIdConverter(
+ const unsigned char *CallStackBase,
+ llvm::function_ref<Frame(LinearFrameId)> FrameIdToFrame)
+ : CallStackBase(CallStackBase), FrameIdToFrame(FrameIdToFrame) {}
+
+ std::vector<Frame> operator()(LinearCallStackId LinearCSId) {
+ std::vector<Frame> Frames;
+
+ const unsigned char *Ptr =
+ CallStackBase +
+ static_cast<uint64_t>(LinearCSId) * sizeof(LinearFrameId);
+ uint32_t NumFrames =
+ support::endian::readNext<uint32_t, llvm::endianness::little>(Ptr);
+ Frames.reserve(NumFrames);
+ for (; NumFrames; --NumFrames) {
+ LinearFrameId Elem =
+ support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
+ // Follow a pointer to the parent, if any. See comments below on
+ // CallStackRadixTreeBuilder for the description of the radix tree format.
+ if (static_cast<std::make_signed_t<LinearFrameId>>(Elem) < 0) {
+ Ptr += (-Elem) * sizeof(LinearFrameId);
+ Elem =
+ support::endian::read<LinearFrameId, llvm::endianness::little>(Ptr);
+ }
+ // We shouldn't encounter another pointer.
+ assert(static_cast<std::make_signed_t<LinearFrameId>>(Elem) >= 0);
+ Frames.push_back(FrameIdToFrame(Elem));
+ Ptr += sizeof(LinearFrameId);
+ }
+
+ return Frames;
+ }
+};
+
+// Used to extract caller-callee pairs from the call stack array. The leaf
+// frame is assumed to call a heap allocation function with GUID 0. The
+// resulting pairs are accumulated in CallerCalleePairs. Users can take it
+// with:
+//
+// auto Pairs = std::move(Extractor.CallerCalleePairs);
+struct CallerCalleePairExtractor {
+ /...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/140501
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