https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114413
Bug ID: 114413
Summary: BB SLP sub-graph merging fails to CSE nodes
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
The gcc.dg/vect/bb-slp-32.c shows that while we now discover both the store
and the reduction as BB vectorization opportunities we merge the SLP
instances into the same graph because they overlap but fail to unify
nodes within them so both costing and code-generation is off duplicating
the load and the adds:
<bb 2> [local count: 1073741824]:
_36 = {a_12(D), b_15(D), b_15(D), a_12(D)};
_30 = {a_12(D), b_15(D), b_15(D), a_12(D)};
p_10 = __builtin_assume_aligned (p_9(D), 16);
vectp.4_27 = p_10;
vect__1.5_28 = MEM <vector(4) int> [(int *)vectp.4_27];
vect__2.6_29 = vect__1.5_28 + { 1, 2, 3, 4 };
vect_tem0_13.7_31 = vect__2.6_29 + _30;
vectp.11_33 = p_10;
vect__7.12_34 = MEM <vector(4) int> [(int *)vectp.11_33];
vect__8.13_35 = vect__7.12_34 + { 1, 2, 3, 4 };
vect_tem3_22.14_37 = vect__8.13_35 + _36;
_1 = *p_10;
_2 = _1 + 1;
tem0_13 = _2 + a_12(D);
_3 = MEM[(int *)p_10 + 4B];
_4 = _3 + 2;
tem1_16 = _4 + b_15(D);
sum_17 = tem0_13 + tem1_16;
_5 = MEM[(int *)p_10 + 8B];
_6 = _5 + 3;
tem2_19 = _6 + b_15(D);
sum_20 = sum_17 + tem2_19;
_7 = MEM[(int *)p_10 + 12B];
_8 = _7 + 4;
tem3_22 = _8 + a_12(D);
_38 = VIEW_CONVERT_EXPR<vector(4) unsigned int>(vect_tem3_22.14_37);
_39 = .REDUC_PLUS (_38);
_40 = (int) _39;
sum_23 = _40;
MEM <vector(4) int> [(int *)&x] = vect_tem0_13.7_31;
bar (&x);
x ={v} {CLOBBER(eos)};
but the vectorization should be profitable, we CSE this to
foo:
.LFB0:
.cfi_startproc
pushq %rbx
.cfi_def_cfa_offset 16
.cfi_offset 3, -16
movd %edx, %xmm2
movd %esi, %xmm0
movdqa %xmm2, %xmm3
punpckldq %xmm0, %xmm3
punpckldq %xmm2, %xmm0
subq $16, %rsp
.cfi_def_cfa_offset 32
movdqa .LC0(%rip), %xmm1
paddd (%rdi), %xmm1
punpcklqdq %xmm3, %xmm0
movq %rsp, %rdi
paddd %xmm0, %xmm1
movdqa %xmm1, %xmm0
movaps %xmm1, (%rsp)
psrldq $8, %xmm0
paddd %xmm1, %xmm0
movdqa %xmm0, %xmm2
psrldq $4, %xmm2
paddd %xmm2, %xmm0
movd %xmm0, %ebx
call bar
addq $16, %rsp
.cfi_def_cfa_offset 16
movl %ebx, %eax
popq %rbx
.cfi_def_cfa_offset 8
ret
in the end.
