https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95199
Bug ID: 95199
Summary: Remove extra variable created for memory reference in
loop vectorization.
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zhoukaipeng3 at huawei dot com
Target Milestone: ---
The function vect_create_data_ref_ptr created two equal variable for two equal
memory references.
gcc version 11.0.0 20200515 (experimental) (GCC)
Target: aarch64-unknown-linux-gnu
Configured with: ../configure
Command: gcc -O2 -march=armv8.2-a+fp+sve -ftree-vectorize test.c -S
Testcase:
void
foo (double *a, double *b, double m, int inc_x, int inc_y) {
int ix = 0, iy = 0;
for (int i = 0; i < 1000; ++i)
{
a[ix] += m * b[iy];
ix += inc_x;
iy += inc_y;
}
return ;
}
Assembly code
.L5:
ld1d z3.d, p0/z, [x5, z2.d, lsl 3]
ld1d z1.d, p0/z, [x3, z4.d, lsl 3]
fmad z1.d, p1/m, z0.d, z3.d
st1d z1.d, p0, [x2, z2.d, lsl 3]
incd x1
add x5, x5, x6
add x3, x3, x4
add x2, x2, x6
whilelo p0.d, x1, x0
b.any .L5
x2 is the same as x5.
vectorizable_load and vectorizable_store called vect_create_data_ref_ptr twice
for a[ix].
Dump Log in test.c.161.vect
test.c:4:2: note: create real_type-pointer variable to type: double
vectorizing a pointer ref: *a_16(D)
test.c:4:2: note: created a_16(D)
test.c:4:2: note: add new stmt: vect__4.5_94 = .MASK_GATHER_LOAD
(vectp_a.3_91, _90, 8, { 0.0, ... }, loop_mask_93);
...
test.c:4:2: note: create real_type-pointer variable to type: double
vectorizing a pointer ref: *a_16(D)
test.c:4:2: note: created a_16(D)
test.c:4:2: note: add new stmt: .MASK_SCATTER_STORE (vectp_a.11_117, _116, 8,
vect__10.10_108, loop_mask_93);
I plan to add a hash_map to loop_vec_info for dr and the corresponding pointer
created by vect_create_data_ref_ptr. If the dr->ref has been handled, return
the corresponding pointer.
Optimized assembly code
.L3:
ld1d z2.d, p0/z, [x0, z1.d, lsl 3]
ld1d z0.d, p0/z, [x1, z4.d, lsl 3]
fmad z0.d, p1/m, z3.d, z2.d
st1d z0.d, p0, [x0, z1.d, lsl 3]
incd x2
add x0, x0, x5
add x1, x1, x4
whilelo p0.d, w2, w3
b.any .L3
ret
