[llvm] r257532 - [Support] Add saturating multiply-add support function
Nathan Slingerland via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 12 14:34:01 PST 2016
Author: slingn
Date: Tue Jan 12 16:34:00 2016
New Revision: 257532
URL: http://llvm.org/viewvc/llvm-project?rev=257532&view=rev
Log:
[Support] Add saturating multiply-add support function
Summary: Add SaturatingMultiplyAdd convenience function template since A + (X * Y) comes up frequently when doing weighted arithmetic.
Reviewers: davidxl, silvas
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D15385
Modified:
llvm/trunk/include/llvm/ProfileData/SampleProf.h
llvm/trunk/include/llvm/Support/MathExtras.h
llvm/trunk/lib/ProfileData/InstrProf.cpp
llvm/trunk/unittests/Support/MathExtrasTest.cpp
Modified: llvm/trunk/include/llvm/ProfileData/SampleProf.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ProfileData/SampleProf.h?rev=257532&r1=257531&r2=257532&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ProfileData/SampleProf.h (original)
+++ llvm/trunk/include/llvm/ProfileData/SampleProf.h Tue Jan 12 16:34:00 2016
@@ -140,16 +140,9 @@ public:
/// around unsigned integers.
sampleprof_error addSamples(uint64_t S, uint64_t Weight = 1) {
bool Overflowed;
- if (Weight > 1) {
- S = SaturatingMultiply(S, Weight, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
- }
- NumSamples = SaturatingAdd(NumSamples, S, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
-
- return sampleprof_error::success;
+ NumSamples = SaturatingMultiplyAdd(S, Weight, NumSamples, &Overflowed);
+ return Overflowed ? sampleprof_error::counter_overflow
+ : sampleprof_error::success;
}
/// Add called function \p F with samples \p S.
@@ -161,16 +154,10 @@ public:
uint64_t Weight = 1) {
uint64_t &TargetSamples = CallTargets[F];
bool Overflowed;
- if (Weight > 1) {
- S = SaturatingMultiply(S, Weight, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
- }
- TargetSamples = SaturatingAdd(TargetSamples, S, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
-
- return sampleprof_error::success;
+ TargetSamples =
+ SaturatingMultiplyAdd(S, Weight, TargetSamples, &Overflowed);
+ return Overflowed ? sampleprof_error::counter_overflow
+ : sampleprof_error::success;
}
/// Return true if this sample record contains function calls.
@@ -215,29 +202,17 @@ public:
void dump() const;
sampleprof_error addTotalSamples(uint64_t Num, uint64_t Weight = 1) {
bool Overflowed;
- if (Weight > 1) {
- Num = SaturatingMultiply(Num, Weight, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
- }
- TotalSamples = SaturatingAdd(TotalSamples, Num, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
-
- return sampleprof_error::success;
+ TotalSamples =
+ SaturatingMultiplyAdd(Num, Weight, TotalSamples, &Overflowed);
+ return Overflowed ? sampleprof_error::counter_overflow
+ : sampleprof_error::success;
}
sampleprof_error addHeadSamples(uint64_t Num, uint64_t Weight = 1) {
bool Overflowed;
- if (Weight > 1) {
- Num = SaturatingMultiply(Num, Weight, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
- }
- TotalHeadSamples = SaturatingAdd(TotalHeadSamples, Num, &Overflowed);
- if (Overflowed)
- return sampleprof_error::counter_overflow;
-
- return sampleprof_error::success;
+ TotalHeadSamples =
+ SaturatingMultiplyAdd(Num, Weight, TotalHeadSamples, &Overflowed);
+ return Overflowed ? sampleprof_error::counter_overflow
+ : sampleprof_error::success;
}
sampleprof_error addBodySamples(uint32_t LineOffset, uint32_t Discriminator,
uint64_t Num, uint64_t Weight = 1) {
Modified: llvm/trunk/include/llvm/Support/MathExtras.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/MathExtras.h?rev=257532&r1=257531&r2=257532&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/MathExtras.h (original)
+++ llvm/trunk/include/llvm/Support/MathExtras.h Tue Jan 12 16:34:00 2016
@@ -717,6 +717,25 @@ SaturatingMultiply(T X, T Y, bool *Resul
return Z;
}
+/// \brief Multiply two unsigned integers, X and Y, and add the unsigned
+/// integer, A to the product. Clamp the result to the maximum representable
+/// value of T on overflow. ResultOverflowed indicates if the result is larger
+/// than the maximum representable value of type T.
+/// Note that this is purely a convenience function as there is no distinction
+/// where overflow occurred in a 'fused' multiply-add for unsigned numbers.
+template <typename T>
+typename std::enable_if<std::is_unsigned<T>::value, T>::type
+SaturatingMultiplyAdd(T X, T Y, T A, bool *ResultOverflowed = nullptr) {
+ bool Dummy;
+ bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
+
+ T Product = SaturatingMultiply(X, Y, &Overflowed);
+ if (Overflowed)
+ return Product;
+
+ return SaturatingAdd(A, Product, &Overflowed);
+}
+
extern const float huge_valf;
} // End llvm namespace
Modified: llvm/trunk/lib/ProfileData/InstrProf.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ProfileData/InstrProf.cpp?rev=257532&r1=257531&r2=257532&view=diff
==============================================================================
--- llvm/trunk/lib/ProfileData/InstrProf.cpp (original)
+++ llvm/trunk/lib/ProfileData/InstrProf.cpp Tue Jan 12 16:34:00 2016
@@ -269,14 +269,8 @@ instrprof_error InstrProfValueSiteRecord
while (I != IE && I->Value < J->Value)
++I;
if (I != IE && I->Value == J->Value) {
- uint64_t JCount = J->Count;
bool Overflowed;
- if (Weight > 1) {
- JCount = SaturatingMultiply(JCount, Weight, &Overflowed);
- if (Overflowed)
- Result = instrprof_error::counter_overflow;
- }
- I->Count = SaturatingAdd(I->Count, JCount, &Overflowed);
+ I->Count = SaturatingMultiplyAdd(J->Count, Weight, I->Count, &Overflowed);
if (Overflowed)
Result = instrprof_error::counter_overflow;
++I;
@@ -328,13 +322,8 @@ instrprof_error InstrProfRecord::merge(I
for (size_t I = 0, E = Other.Counts.size(); I < E; ++I) {
bool Overflowed;
- uint64_t OtherCount = Other.Counts[I];
- if (Weight > 1) {
- OtherCount = SaturatingMultiply(OtherCount, Weight, &Overflowed);
- if (Overflowed)
- Result = instrprof_error::counter_overflow;
- }
- Counts[I] = SaturatingAdd(Counts[I], OtherCount, &Overflowed);
+ Counts[I] =
+ SaturatingMultiplyAdd(Other.Counts[I], Weight, Counts[I], &Overflowed);
if (Overflowed)
Result = instrprof_error::counter_overflow;
}
Modified: llvm/trunk/unittests/Support/MathExtrasTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/MathExtrasTest.cpp?rev=257532&r1=257531&r2=257532&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/MathExtrasTest.cpp (original)
+++ llvm/trunk/unittests/Support/MathExtrasTest.cpp Tue Jan 12 16:34:00 2016
@@ -304,4 +304,58 @@ TEST(MathExtras, SaturatingMultiply) {
SaturatingMultiplyTestHelper<uint64_t>();
}
+template<typename T>
+void SaturatingMultiplyAddTestHelper()
+{
+ const T Max = std::numeric_limits<T>::max();
+ bool ResultOverflowed;
+
+ // Test basic multiply-add.
+ EXPECT_EQ(T(16), SaturatingMultiplyAdd(T(2), T(3), T(10)));
+ EXPECT_EQ(T(16), SaturatingMultiplyAdd(T(2), T(3), T(10), &ResultOverflowed));
+ EXPECT_FALSE(ResultOverflowed);
+
+ // Test multiply overflows, add doesn't overflow
+ EXPECT_EQ(Max, SaturatingMultiplyAdd(Max, Max, T(0), &ResultOverflowed));
+ EXPECT_TRUE(ResultOverflowed);
+
+ // Test multiply doesn't overflow, add overflows
+ EXPECT_EQ(Max, SaturatingMultiplyAdd(T(1), T(1), Max, &ResultOverflowed));
+ EXPECT_TRUE(ResultOverflowed);
+
+ // Test multiply-add with Max as operand
+ EXPECT_EQ(Max, SaturatingMultiplyAdd(T(1), T(1), Max, &ResultOverflowed));
+ EXPECT_TRUE(ResultOverflowed);
+
+ EXPECT_EQ(Max, SaturatingMultiplyAdd(T(1), Max, T(1), &ResultOverflowed));
+ EXPECT_TRUE(ResultOverflowed);
+
+ EXPECT_EQ(Max, SaturatingMultiplyAdd(Max, Max, T(1), &ResultOverflowed));
+ EXPECT_TRUE(ResultOverflowed);
+
+ EXPECT_EQ(Max, SaturatingMultiplyAdd(Max, Max, Max, &ResultOverflowed));
+ EXPECT_TRUE(ResultOverflowed);
+
+ // Test multiply-add with 0 as operand
+ EXPECT_EQ(T(1), SaturatingMultiplyAdd(T(1), T(1), T(0), &ResultOverflowed));
+ EXPECT_FALSE(ResultOverflowed);
+
+ EXPECT_EQ(T(1), SaturatingMultiplyAdd(T(1), T(0), T(1), &ResultOverflowed));
+ EXPECT_FALSE(ResultOverflowed);
+
+ EXPECT_EQ(T(1), SaturatingMultiplyAdd(T(0), T(0), T(1), &ResultOverflowed));
+ EXPECT_FALSE(ResultOverflowed);
+
+ EXPECT_EQ(T(0), SaturatingMultiplyAdd(T(0), T(0), T(0), &ResultOverflowed));
+ EXPECT_FALSE(ResultOverflowed);
+
+}
+
+TEST(MathExtras, SaturatingMultiplyAdd) {
+ SaturatingMultiplyAddTestHelper<uint8_t>();
+ SaturatingMultiplyAddTestHelper<uint16_t>();
+ SaturatingMultiplyAddTestHelper<uint32_t>();
+ SaturatingMultiplyAddTestHelper<uint64_t>();
+}
+
}
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