[llvm] r253497 - [llvm-profdata] Add SaturatingAdd/SaturatingMultiply Helper Functions (2nd try)
Nathan Slingerland via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 18 12:40:44 PST 2015
Author: slingn
Date: Wed Nov 18 14:40:41 2015
New Revision: 253497
URL: http://llvm.org/viewvc/llvm-project?rev=253497&view=rev
Log:
[llvm-profdata] Add SaturatingAdd/SaturatingMultiply Helper Functions (2nd try)
Summary:
This change adds MathExtras helper functions for handling unsigned, saturating addition and multiplication. It also updates the instrumentation and sample profile merge implementations to use them.
Reviewers: dnovillo, bogner, davidxl
Subscribers: davidxl, llvm-commits
Differential Revision: http://reviews.llvm.org/D14720
Modified:
llvm/trunk/include/llvm/ProfileData/InstrProf.h
llvm/trunk/include/llvm/ProfileData/SampleProf.h
llvm/trunk/include/llvm/Support/MathExtras.h
llvm/trunk/unittests/ProfileData/InstrProfTest.cpp
llvm/trunk/unittests/Support/MathExtrasTest.cpp
Modified: llvm/trunk/include/llvm/ProfileData/InstrProf.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ProfileData/InstrProf.h?rev=253497&r1=253496&r2=253497&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ProfileData/InstrProf.h (original)
+++ llvm/trunk/include/llvm/ProfileData/InstrProf.h Wed Nov 18 14:40:41 2015
@@ -226,7 +226,7 @@ struct InstrProfValueSiteRecord {
while (I != IE && I->Value < J->Value)
++I;
if (I != IE && I->Value == J->Value) {
- I->Count += J->Count;
+ I->Count = SaturatingAdd(I->Count, J->Count);
++I;
continue;
}
Modified: llvm/trunk/include/llvm/ProfileData/SampleProf.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ProfileData/SampleProf.h?rev=253497&r1=253496&r2=253497&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ProfileData/SampleProf.h (original)
+++ llvm/trunk/include/llvm/ProfileData/SampleProf.h Wed Nov 18 14:40:41 2015
@@ -173,10 +173,7 @@ public:
/// Sample counts accumulate using saturating arithmetic, to avoid wrapping
/// around unsigned integers.
void addSamples(uint64_t S) {
- if (NumSamples <= std::numeric_limits<uint64_t>::max() - S)
- NumSamples += S;
- else
- NumSamples = std::numeric_limits<uint64_t>::max();
+ NumSamples = SaturatingAdd(NumSamples, S);
}
/// Add called function \p F with samples \p S.
@@ -185,10 +182,7 @@ public:
/// around unsigned integers.
void addCalledTarget(StringRef F, uint64_t S) {
uint64_t &TargetSamples = CallTargets[F];
- if (TargetSamples <= std::numeric_limits<uint64_t>::max() - S)
- TargetSamples += S;
- else
- TargetSamples = std::numeric_limits<uint64_t>::max();
+ TargetSamples = SaturatingAdd(TargetSamples, S);
}
/// Return true if this sample record contains function calls.
Modified: llvm/trunk/include/llvm/Support/MathExtras.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/MathExtras.h?rev=253497&r1=253496&r2=253497&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/MathExtras.h (original)
+++ llvm/trunk/include/llvm/Support/MathExtras.h Wed Nov 18 14:40:41 2015
@@ -653,6 +653,32 @@ inline int64_t SignExtend64(uint64_t X,
return int64_t(X << (64 - B)) >> (64 - B);
}
+/// \brief Add two unsigned integers, X and Y, of type T.
+/// Clamp the result to the maximum representable value of T on overflow.
+template <typename T>
+typename std::enable_if<std::is_unsigned<T>::value, T>::type
+SaturatingAdd(T X, T Y) {
+ // Hacker's Delight, p. 29
+ T Z = X + Y;
+ if (Z < X || Z < Y)
+ return std::numeric_limits<T>::max();
+ else
+ return Z;
+}
+
+/// \brief Multiply two unsigned integers, X and Y, of type T.
+/// Clamp the result to the maximum representable value of T on overflow.
+template <typename T>
+typename std::enable_if<std::is_unsigned<T>::value, T>::type
+SaturatingMultiply(T X, T Y) {
+ // Hacker's Delight, p. 30
+ T Z = X * Y;
+ if (Y != 0 && Z / Y != X)
+ return std::numeric_limits<T>::max();
+ else
+ return Z;
+}
+
extern const float huge_valf;
} // End llvm namespace
Modified: llvm/trunk/unittests/ProfileData/InstrProfTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ProfileData/InstrProfTest.cpp?rev=253497&r1=253496&r2=253497&view=diff
==============================================================================
--- llvm/trunk/unittests/ProfileData/InstrProfTest.cpp (original)
+++ llvm/trunk/unittests/ProfileData/InstrProfTest.cpp Wed Nov 18 14:40:41 2015
@@ -350,6 +350,38 @@ TEST_F(InstrProfTest, get_icall_data_mer
ASSERT_EQ(2U, VD_4[2].Count);
}
+TEST_F(InstrProfTest, get_icall_data_merge1_saturation) {
+ const uint64_t Max = std::numeric_limits<uint64_t>::max();
+
+ InstrProfRecord Record1("caller", 0x1234, {1});
+ InstrProfRecord Record2("caller", 0x1234, {1});
+ InstrProfRecord Record3("callee1", 0x1235, {3, 4});
+
+ Record1.reserveSites(IPVK_IndirectCallTarget, 1);
+ InstrProfValueData VD1[] = {{(uint64_t) "callee1", 1}};
+ Record1.addValueData(IPVK_IndirectCallTarget, 0, VD1, 1, nullptr);
+
+ Record2.reserveSites(IPVK_IndirectCallTarget, 1);
+ InstrProfValueData VD2[] = {{(uint64_t) "callee1", Max}};
+ Record2.addValueData(IPVK_IndirectCallTarget, 0, VD2, 1, nullptr);
+
+ Writer.addRecord(std::move(Record1));
+ Writer.addRecord(std::move(Record2));
+ Writer.addRecord(std::move(Record3));
+
+ auto Profile = Writer.writeBuffer();
+ readProfile(std::move(Profile));
+
+ // Verify saturation of counts.
+ ErrorOr<InstrProfRecord> R = Reader->getInstrProfRecord("caller", 0x1234);
+ ASSERT_TRUE(NoError(R.getError()));
+ ASSERT_EQ(1U, R.get().getNumValueSites(IPVK_IndirectCallTarget));
+ std::unique_ptr<InstrProfValueData[]> VD =
+ R.get().getValueForSite(IPVK_IndirectCallTarget, 0);
+ ASSERT_EQ(StringRef("callee1"), StringRef((const char *)VD[0].Value, 7));
+ ASSERT_EQ(Max, VD[0].Count);
+}
+
TEST_F(InstrProfTest, get_max_function_count) {
InstrProfRecord Record1("foo", 0x1234, {1ULL << 31, 2});
InstrProfRecord Record2("bar", 0, {1ULL << 63});
Modified: llvm/trunk/unittests/Support/MathExtrasTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/MathExtrasTest.cpp?rev=253497&r1=253496&r2=253497&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/MathExtrasTest.cpp (original)
+++ llvm/trunk/unittests/Support/MathExtrasTest.cpp Wed Nov 18 14:40:41 2015
@@ -190,4 +190,40 @@ TEST(MathExtras, RoundUpToAlignment) {
EXPECT_EQ(552u, RoundUpToAlignment(321, 255, 42));
}
+template<typename T>
+void SaturatingAddTestHelper()
+{
+ const T Max = std::numeric_limits<T>::max();
+ EXPECT_EQ(T(3), SaturatingAdd(T(1), T(2)));
+ EXPECT_EQ(Max, SaturatingAdd(Max, T(1)));
+ EXPECT_EQ(Max, SaturatingAdd(T(1), Max));
+ EXPECT_EQ(Max, SaturatingAdd(Max, Max));
+}
+
+TEST(MathExtras, SaturatingAdd) {
+ SaturatingAddTestHelper<uint8_t>();
+ SaturatingAddTestHelper<uint16_t>();
+ SaturatingAddTestHelper<uint32_t>();
+ SaturatingAddTestHelper<uint64_t>();
+}
+
+template<typename T>
+void SaturatingMultiplyTestHelper()
+{
+ const T Max = std::numeric_limits<T>::max();
+ EXPECT_EQ(T(0), SaturatingMultiply(T(1), T(0)));
+ EXPECT_EQ(T(0), SaturatingMultiply(T(0), T(1)));
+ EXPECT_EQ(T(6), SaturatingMultiply(T(2), T(3)));
+ EXPECT_EQ(Max, SaturatingMultiply(Max, T(2)));
+ EXPECT_EQ(Max, SaturatingMultiply(T(2),Max));
+ EXPECT_EQ(Max, SaturatingMultiply(Max, Max));
+}
+
+TEST(MathExtras, SaturatingMultiply) {
+ SaturatingMultiplyTestHelper<uint8_t>();
+ SaturatingMultiplyTestHelper<uint16_t>();
+ SaturatingMultiplyTestHelper<uint32_t>();
+ SaturatingMultiplyTestHelper<uint64_t>();
+}
+
}
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