https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86024
Bug ID: 86024
Summary: Missed memcpy loop distribution with elementwise copy
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: glisse at gcc dot gnu.org
Target Milestone: ---
typedef struct A { int a, b; } A;
void*f(A*restrict p){
A*q=__builtin_malloc(1024*sizeof(A));
for(int i=0;i<1024;++i){
#ifdef HELP
q[i]=p[i];
#else
q[i].a=p[i].a;
q[i].b=p[i].b;
#endif
}
return q;
}
At -O3, with HELP, we get the expected memcpy. Without it, the loop is only
vectorized.
