http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49773
Summary: use of class data members prevent vectorization
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: [email protected]
ReportedBy: [email protected]
in this example below the loop in the first method does not vectorize, the
second does.
struct Foo {
float a;
float b;
void compute1(float * __restrict__ x, float const * __restrict__ y, int N)
const;
void compute2(float * __restrict__ x, float const * __restrict__ y, int N)
const;
};
void Foo::compute1(float * __restrict__ x, float const * __restrict__ y, int N)
const {
for (int i=0; i!=N; ++i)
x[i] = a + b*y[i];
}
void Foo::compute2(float * __restrict__ x, float const * __restrict__ y, int N)
const {
float la=a, lb=b;
for (int i=0; i!=N; ++i)
x[i] = la + lb*y[i];
}
test/vectClass.cpp:11: note: not vectorized: loop contains function calls or
data references that cannot be analyzed
test/vectClass.cpp:10: note: vectorized 0 loops in function.
vs
test/vectClass.cpp:17: note: Profitability threshold is 5 loop iterations.
test/vectClass.cpp:17: note: LOOP VECTORIZED.
test/vectClass.cpp:15: note: vectorized 1 loops in function.
