https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113261
Bug ID: 113261
Summary: missing vectorization for dot_prod chain.
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: liuhongt at gcc dot gnu.org
Blocks: 53947
Target Milestone: ---
int
foo (char* a, char* b, char* c, char* d)
{
int sum = 0;
for (int i = 0; i != 32; i++)
{
sum += (a[i] * b[i] + c[i] * d[i]);
}
return sum;
}
int
foo1 (char* a, char* b, char* c, char* d)
{
int sum = 0;
int sum1 = 0;
for (int i = 0; i != 32; i++)
{
sum += a[i] * b[i]
sum1 += c[i] * d[i];
}
return sum + sum1;
}
foo should be same as foo1, but it failed to be optimized to dot_prod_expr
since current vect_recog_dot_prod_pattern only recognize sum += a[i] * b[i];
I think it can be extend to recog dot_prod_expr chain, as long as they're only
used by the final sum reduction.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
