[llvm] 8423a6f - Rename OptimalLayout to OptimizedStructLayout at Chris's request.
John McCall via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 9 21:14:28 PDT 2020
Author: John McCall
Date: 2020-04-10T00:14:20-04:00
New Revision: 8423a6f36386aabced2a367c0ea53487901d31ca
URL: https://github.com/llvm/llvm-project/commit/8423a6f36386aabced2a367c0ea53487901d31ca
DIFF: https://github.com/llvm/llvm-project/commit/8423a6f36386aabced2a367c0ea53487901d31ca.diff
LOG: Rename OptimalLayout to OptimizedStructLayout at Chris's request.
Added:
llvm/include/llvm/Support/OptimizedStructLayout.h
llvm/lib/Support/OptimizedStructLayout.cpp
llvm/unittests/Support/OptimizedStructLayoutTest.cpp
Modified:
llvm/lib/Support/CMakeLists.txt
llvm/lib/Transforms/Coroutines/CoroFrame.cpp
llvm/unittests/Support/CMakeLists.txt
llvm/utils/gn/secondary/llvm/lib/Support/BUILD.gn
llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
Removed:
llvm/include/llvm/Support/OptimalLayout.h
llvm/lib/Support/OptimalLayout.cpp
llvm/unittests/Support/OptimalLayoutTest.cpp
################################################################################
diff --git a/llvm/include/llvm/Support/OptimalLayout.h b/llvm/include/llvm/Support/OptimizedStructLayout.h
similarity index 74%
rename from llvm/include/llvm/Support/OptimalLayout.h
rename to llvm/include/llvm/Support/OptimizedStructLayout.h
index 870dc78791bb..773ddfeaf13a 100644
--- a/llvm/include/llvm/Support/OptimalLayout.h
+++ b/llvm/include/llvm/Support/OptimizedStructLayout.h
@@ -1,4 +1,4 @@
-//===-- OptimalLayout.h - Optimal data layout algorithm -----------*- C++ -*-=//
+//===-- OptimizedStructLayout.h - Struct layout algorithm ---------*- C++ -*-=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
@@ -8,19 +8,31 @@
///
/// This file provides an interface for laying out a sequence of fields
/// as a struct in a way that attempts to minimizes the total space
-/// requirements of the struct.
+/// requirements of the struct while still satisfying the layout
+/// requirements of the individual fields. The resulting layout may be
+/// substantially more compact than simply laying out the fields in their
+/// original order.
///
-/// The word "optimal" is a misnomer in several ways. First, minimizing
-/// space usage doesn't necessarily yield optimal performance because it
-/// may decrease locality. Second, there is no known efficient algorithm
-/// that guarantees a minimal layout for arbitrary inputs. Nonetheless,
-/// this algorithm is likely to produce much more compact layouts than
-/// would be produced by just allocating space in a buffer.
+/// Fields may be pre-assigned fixed offsets. They may also be given sizes
+/// that are not multiples of their alignments. There is no currently no
+/// way to describe that a field has interior padding that other fields may
+/// be allocated into.
+///
+/// This algorithm does not claim to be "optimal" for several reasons:
+///
+/// - First, it does not guarantee that the result is minimal in size.
+/// There is no known efficient algoorithm to achieve minimality for
+/// unrestricted inputs. Nonetheless, this algorithm
+///
+/// - Second, there are other ways that a struct layout could be optimized
+/// besides space usage, such as locality. This layout may have a mixed
+/// impact on locality: less overall memory may be used, but adjacent
+/// fields in the original array may be moved further from one another.
///
//===----------------------------------------------------------------------===//
-#ifndef LLVM_SUPPORT_OPTIMALLAYOUT_H
-#define LLVM_SUPPORT_OPTIMALLAYOUT_H
+#ifndef LLVM_SUPPORT_OPTIMIZEDSTRUCTLAYOUT_H
+#define LLVM_SUPPORT_OPTIMIZEDSTRUCTLAYOUT_H
#include "llvm/Support/Alignment.h"
#include "llvm/ADT/ArrayRef.h"
@@ -29,13 +41,13 @@
namespace llvm {
/// A field in a structure.
-struct OptimalLayoutField {
+struct OptimizedStructLayoutField {
/// A special value for Offset indicating that the field can be moved
/// anywhere.
static constexpr uint64_t FlexibleOffset = ~(uint64_t)0;
- OptimalLayoutField(const void *Id, uint64_t Size, Align Alignment,
- uint64_t FixedOffset = FlexibleOffset)
+ OptimizedStructLayoutField(const void *Id, uint64_t Size, Align Alignment,
+ uint64_t FixedOffset = FlexibleOffset)
: Offset(FixedOffset), Size(Size), Id(Id), Alignment(Alignment) {
assert(Size > 0 && "adding an empty field to the layout");
}
@@ -122,8 +134,8 @@ struct OptimalLayoutField {
/// The return value is the total size of the struct and its required
/// alignment. Note that the total size is not rounded up to a multiple
/// of the required alignment; clients which require this can do so easily.
-std::pair<uint64_t, Align>
-performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields);
+std::pair<uint64_t, Align> performOptimizedStructLayout(
+ MutableArrayRef<OptimizedStructLayoutField> Fields);
} // namespace llvm
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 25e1be673300..897f183b660f 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -117,7 +117,7 @@ add_llvm_component_library(LLVMSupport
MemoryBuffer.cpp
MD5.cpp
NativeFormatting.cpp
- OptimalLayout.cpp
+ OptimizedStructLayout.cpp
Optional.cpp
Parallel.cpp
PluginLoader.cpp
diff --git a/llvm/lib/Support/OptimalLayout.cpp b/llvm/lib/Support/OptimizedStructLayout.cpp
similarity index 93%
rename from llvm/lib/Support/OptimalLayout.cpp
rename to llvm/lib/Support/OptimizedStructLayout.cpp
index 93f912bf73a3..9bbd767c5ce9 100644
--- a/llvm/lib/Support/OptimalLayout.cpp
+++ b/llvm/lib/Support/OptimizedStructLayout.cpp
@@ -1,4 +1,4 @@
-//===--- OptimalLayout.cpp - Optimal data layout algorithm ----------------===//
+//===--- OptimizedStructLayout.cpp - Optimal data layout algorithm ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
@@ -6,16 +6,18 @@
//
//===----------------------------------------------------------------------===//
//
-// This file implements the performOptimalLayout interface.
+// This file implements the performOptimizedStructLayout interface.
//
//===----------------------------------------------------------------------===//
-#include "llvm/Support/OptimalLayout.h"
+#include "llvm/Support/OptimizedStructLayout.h"
using namespace llvm;
+using Field = OptimizedStructLayoutField;
+
#ifndef NDEBUG
-static void checkValidLayout(ArrayRef<OptimalLayoutField> Fields, uint64_t Size,
+static void checkValidLayout(ArrayRef<Field> Fields, uint64_t Size,
Align MaxAlign) {
uint64_t LastEnd = 0;
Align ComputedMaxAlign;
@@ -37,7 +39,7 @@ static void checkValidLayout(ArrayRef<OptimalLayoutField> Fields, uint64_t Size,
#endif
std::pair<uint64_t, Align>
-llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
+llvm::performOptimizedStructLayout(MutableArrayRef<Field> Fields) {
#ifndef NDEBUG
// Do some simple precondition checks.
{
@@ -101,8 +103,7 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
// important if we get into the gap-filling stage below, but it
// doesn't hurt here.
array_pod_sort(FirstFlexible, E,
- [](const OptimalLayoutField *lhs,
- const OptimalLayoutField *rhs) -> int {
+ [](const Field *lhs, const Field *rhs) -> int {
// Decreasing alignment.
if (lhs->Alignment != rhs->Alignment)
return (lhs->Alignment < rhs->Alignment ? 1 : -1);
@@ -240,13 +241,13 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
/// monotonically descending in size and otherwise in the original order.
///
/// We remove the queue from the array as soon as this is empty.
- OptimalLayoutField *Head;
+ OptimizedStructLayoutField *Head;
/// The alignment requirement of the queue.
Align Alignment;
- static OptimalLayoutField *getNext(OptimalLayoutField *Cur) {
- return static_cast<OptimalLayoutField*>(Cur->Scratch);
+ static Field *getNext(Field *Cur) {
+ return static_cast<Field *>(Cur->Scratch);
}
};
SmallVector<AlignmentQueue, 8> FlexibleFieldsByAlignment;
@@ -290,9 +291,7 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
#endif
/// Helper function to remove a field from a queue.
- auto spliceFromQueue = [&](AlignmentQueue *Queue,
- OptimalLayoutField *Last,
- OptimalLayoutField *Cur) {
+ auto spliceFromQueue = [&](AlignmentQueue *Queue, Field *Last, Field *Cur) {
assert(Last ? Queue->getNext(Last) == Cur : Queue->Head == Cur);
// If we're removing Cur from a non-initial position, splice it out
@@ -319,7 +318,7 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
// Do layout into a local array. Doing this in-place on Fields is
// not really feasible.
- SmallVector<OptimalLayoutField, 16> Layout;
+ SmallVector<Field, 16> Layout;
Layout.reserve(Fields.size());
// The offset that we're currently looking to insert at (or after).
@@ -327,9 +326,7 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
// Helper function to splice Cur out of the given queue and add it
// to the layout at the given offset.
- auto addToLayout = [&](AlignmentQueue *Queue,
- OptimalLayoutField *Last,
- OptimalLayoutField *Cur,
+ auto addToLayout = [&](AlignmentQueue *Queue, Field *Last, Field *Cur,
uint64_t Offset) -> bool {
assert(Offset == alignTo(LastEnd, Cur->Alignment));
@@ -362,8 +359,8 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
// Find the matching field. Note that this should always find
// something because of the MinSize check above.
- for (OptimalLayoutField *Cur = Queue->Head, *Last = nullptr;
- true; Last = Cur, Cur = Queue->getNext(Cur)) {
+ for (Field *Cur = Queue->Head, *Last = nullptr; true;
+ Last = Cur, Cur = Queue->getNext(Cur)) {
assert(Cur && "didn't find a match in queue despite its MinSize");
if (Cur->Size <= MaxViableSize)
return addToLayout(Queue, Last, Cur, StartOffset);
@@ -441,7 +438,7 @@ llvm::performOptimalLayout(MutableArrayRef<OptimalLayoutField> Fields) {
// Copy the layout back into place.
assert(Layout.size() == Fields.size());
memcpy(Fields.data(), Layout.data(),
- Fields.size() * sizeof(OptimalLayoutField));
+ Fields.size() * sizeof(OptimizedStructLayoutField));
#ifndef NDEBUG
// Make a final check that the layout is valid.
diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
index e166e28cbcdf..204a4697b705 100644
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -29,7 +29,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/circular_raw_ostream.h"
-#include "llvm/Support/OptimalLayout.h"
+#include "llvm/Support/OptimizedStructLayout.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
@@ -412,7 +412,7 @@ class FrameTypeBuilder {
// Everything else has a flexible offset.
} else {
- Offset = OptimalLayoutField::FlexibleOffset;
+ Offset = OptimizedStructLayoutField::FlexibleOffset;
}
Fields.push_back({FieldSize, Offset, ForSpill, Ty, 0,
@@ -445,7 +445,7 @@ void FrameTypeBuilder::finish(StructType *Ty) {
// Prepare the optimal-layout field array.
// The Id in the layout field is a pointer to our Field for it.
- SmallVector<OptimalLayoutField, 8> LayoutFields;
+ SmallVector<OptimizedStructLayoutField, 8> LayoutFields;
LayoutFields.reserve(Fields.size());
for (auto &Field : Fields) {
LayoutFields.emplace_back(&Field, Field.Size, Field.Alignment,
@@ -453,11 +453,11 @@ void FrameTypeBuilder::finish(StructType *Ty) {
}
// Perform layout.
- auto SizeAndAlign = performOptimalLayout(LayoutFields);
+ auto SizeAndAlign = performOptimizedStructLayout(LayoutFields);
StructSize = SizeAndAlign.first;
StructAlign = SizeAndAlign.second;
- auto getField = [](const OptimalLayoutField &LayoutField) -> Field & {
+ auto getField = [](const OptimizedStructLayoutField &LayoutField) -> Field & {
return *static_cast<Field *>(const_cast<void*>(LayoutField.Id));
};
diff --git a/llvm/unittests/Support/CMakeLists.txt b/llvm/unittests/Support/CMakeLists.txt
index a570a0406d72..b6ed410c0f7f 100644
--- a/llvm/unittests/Support/CMakeLists.txt
+++ b/llvm/unittests/Support/CMakeLists.txt
@@ -52,7 +52,7 @@ add_llvm_unittest(SupportTests
MemoryBufferTest.cpp
MemoryTest.cpp
NativeFormatTests.cpp
- OptimalLayoutTest.cpp
+ OptimizedStructLayoutTest.cpp
ParallelTest.cpp
Path.cpp
ProcessTest.cpp
diff --git a/llvm/unittests/Support/OptimalLayoutTest.cpp b/llvm/unittests/Support/OptimizedStructLayoutTest.cpp
similarity index 82%
rename from llvm/unittests/Support/OptimalLayoutTest.cpp
rename to llvm/unittests/Support/OptimizedStructLayoutTest.cpp
index a31fbaf3f2e6..26d5e27b14b0 100644
--- a/llvm/unittests/Support/OptimalLayoutTest.cpp
+++ b/llvm/unittests/Support/OptimizedStructLayoutTest.cpp
@@ -1,4 +1,4 @@
-//=== - llvm/unittest/Support/OptimalLayoutTest.cpp - Layout tests --------===//
+//=== - unittest/Support/OptimizedStructLayoutTest.cpp - Layout tests -----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
@@ -6,7 +6,7 @@
//
//===----------------------------------------------------------------------===//
-#include "llvm/Support/OptimalLayout.h"
+#include "llvm/Support/OptimizedStructLayout.h"
#include "gtest/gtest.h"
using namespace llvm;
@@ -33,7 +33,7 @@ class LayoutTest {
LayoutTest &flexible(uint64_t Size, uint64_t Alignment,
uint64_t ExpectedOffset) {
Fields.push_back({Size, Align(Alignment),
- OptimalLayoutField::FlexibleOffset, ExpectedOffset});
+ OptimizedStructLayoutField::FlexibleOffset, ExpectedOffset});
return *this;
}
@@ -43,12 +43,12 @@ class LayoutTest {
}
void verify(uint64_t ExpectedSize, uint64_t ExpectedAlignment) {
- SmallVector<OptimalLayoutField, 8> LayoutFields;
+ SmallVector<OptimizedStructLayoutField, 8> LayoutFields;
LayoutFields.reserve(Fields.size());
for (auto &F : Fields)
LayoutFields.emplace_back(&F, F.Size, F.Alignment, F.ForcedOffset);
- auto SizeAndAlign = performOptimalLayout(LayoutFields);
+ auto SizeAndAlign = performOptimizedStructLayout(LayoutFields);
EXPECT_EQ(SizeAndAlign.first, ExpectedSize);
EXPECT_EQ(SizeAndAlign.second, Align(ExpectedAlignment));
@@ -64,7 +64,7 @@ class LayoutTest {
}
-TEST(OptimalLayoutTest, Basic) {
+TEST(OptimizedStructLayoutTest, Basic) {
LayoutTest()
.flexible(12, 4, 8)
.flexible(8, 8, 0)
@@ -72,7 +72,7 @@ TEST(OptimalLayoutTest, Basic) {
.verify(24, 8);
}
-TEST(OptimalLayoutTest, OddSize) {
+TEST(OptimizedStructLayoutTest, OddSize) {
LayoutTest()
.flexible(8, 8, 16)
.flexible(4, 4, 12)
@@ -81,7 +81,7 @@ TEST(OptimalLayoutTest, OddSize) {
.verify(24, 8);
}
-TEST(OptimalLayoutTest, Gaps) {
+TEST(OptimizedStructLayoutTest, Gaps) {
LayoutTest()
.fixed(4, 4, 8)
.fixed(4, 4, 16)
@@ -92,7 +92,7 @@ TEST(OptimalLayoutTest, Gaps) {
.verify(24, 4);
}
-TEST(OptimalLayoutTest, Greed) {
+TEST(OptimizedStructLayoutTest, Greed) {
// The greedy algorithm doesn't find the optimal layout here, which
// would be to put the 5-byte field at the end.
LayoutTest()
@@ -104,7 +104,7 @@ TEST(OptimalLayoutTest, Greed) {
.verify(24, 4);
}
-TEST(OptimalLayoutTest, Jagged) {
+TEST(OptimizedStructLayoutTest, Jagged) {
LayoutTest()
.flexible(1, 2, 18)
.flexible(13, 8, 0)
@@ -112,7 +112,7 @@ TEST(OptimalLayoutTest, Jagged) {
.verify(19, 8);
}
-TEST(OptimalLayoutTest, GardenPath) {
+TEST(OptimizedStructLayoutTest, GardenPath) {
// The 4-byte-aligned field is our highest priority, but the less-aligned
// fields keep leaving the end offset mis-aligned.
LayoutTest()
diff --git a/llvm/utils/gn/secondary/llvm/lib/Support/BUILD.gn b/llvm/utils/gn/secondary/llvm/lib/Support/BUILD.gn
index 13ffdaedfb66..33fac467a5c9 100644
--- a/llvm/utils/gn/secondary/llvm/lib/Support/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/lib/Support/BUILD.gn
@@ -95,7 +95,7 @@ static_library("Support") {
"MathExtras.cpp",
"MemoryBuffer.cpp",
"NativeFormatting.cpp",
- "OptimalLayout.cpp",
+ "OptimizedStructLayout.cpp",
"Optional.cpp",
"Parallel.cpp",
"PluginLoader.cpp",
diff --git a/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn b/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
index c25323955b96..b58a6aba73d7 100644
--- a/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/unittests/Support/BUILD.gn
@@ -55,7 +55,7 @@ unittest("SupportTests") {
"MemoryBufferTest.cpp",
"MemoryTest.cpp",
"NativeFormatTests.cpp",
- "OptimalLayoutTest.cpp",
+ "OptimizedStructLayoutTest.cpp",
"ParallelTest.cpp",
"Path.cpp",
"ProcessTest.cpp",
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