https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112579
Bug ID: 112579
Summary: bb vectorizer failed to reduction sum += inv >>
{1,2,3,4,5,6,7,8}
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: 112325
Target Milestone: ---
This is from PR112325
unsigned
foo (unsigned * restrict s, unsigned qh, unsigned * restrict qs) {
unsigned int sumi = 0;
sumi += (qh >> 0);
sumi += (qh >> 1);
sumi += (qh >> 2);
sumi += (qh >> 3);
sumi += (qh >> 4);
sumi += (qh >> 5);
sumi += (qh >> 6);
sumi += (qh >> 7);
sumi += (qh >> 8);
sumi += (qh >> 9);
sumi += (qh >> 10);
sumi += (qh >> 11);
sumi += (qh >> 12);
sumi += (qh >> 13);
sumi += (qh >> 14);
sumi += (qh >> 15);
return sumi;
}
test2.c:28:8: note: nunits = 8
test2.c:28:8: missed: Build SLP failed: unrolling required in basic block SLP
test2.c:28:8: note: Build SLP for _5 = qh_16(D) >> 5;
test2.c:28:8: note: get vectype for scalar type (group size 14): unsigned int
test2.c:28:8: note: vectype: vector(8) unsigned int
test2.c:28:8: note: nunits = 8
test2.c:28:8: missed: Build SLP failed: unrolling required in basic block SLP
test2.c:28:8: note: Build SLP for _4 = qh_16(D) >> 4;
test2.c:28:8: note: get vectype for scalar type (group size 14): unsigned int
test2.c:28:8: note: vectype: vector(8) unsigned int
test2.c:28:8: note: nunits = 8
test2.c:28:8: missed: Build SLP failed: unrolling required in basic block SLP
test2.c:28:8: note: Build SLP for _3 = qh_16(D) >> 3;
test2.c:28:8: note: get vectype for scalar type (group size 14): unsigned int
test2.c:28:8: note: vectype: vector(8) unsigned int
test2.c:28:8: note: nunits = 8
test2.c:28:8: missed: Build SLP failed: unrolling required in basic block SLP
test2.c:28:8: note: Build SLP for _1 = qh_16(D) >> 1;
test2.c:28:8: note: get vectype for scalar type (group size 14): unsigned int
test2.c:28:8: note: vectype: vector(8) unsigned int
test2.c:28:8: note: nunits = 8
test2.c:28:8: missed: Build SLP failed: unrolling required in basic block SLP
test2.c:28:8: note: SLP discovery for node 0x6415a60 failed
test2.c:28:8: note: SLP discovery failed
rewrite it as
unsigned
foo1 (unsigned * restrict s, unsigned qh, unsigned * restrict qs) {
unsigned int sumi = 0;
for (int i = 0; i != 16; i++)
sumi += qh >> i;
return sumi;
}
loop vectorizer successfully vectorize it.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112325
[Bug 112325] Missed vectorization of reduction after unrolling
