https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63679
--- Comment #7 from Tejas Belagod <belagod at gcc dot gnu.org> ---
I tried this, but it still doesn't seem to fold for aarch64.
So, here is the DOM trace for aarch64:
Optimizing statement a = *.LC0;
LKUP STMT a = *.LC0 with .MEM_3(D)
LKUP STMT *.LC0 = a with .MEM_3(D)
Optimizing statement vectp_a.5_1 = &a;
LKUP STMT vectp_a.5_1 = &a
==== ASGN vectp_a.5_1 = &a
Optimizing statement vect__6.6_13 = MEM[(int *)vectp_a.5_1];
Replaced 'vectp_a.5_1' with constant '&aD.2604'
LKUP STMT vect__6.6_13 = MEM[(int *)&a] with .MEM_4
2>>> STMT vect__6.6_13 = MEM[(int *)&a] with .MEM_4
Optimizing statement vect_sum_7.7_6 = vect__6.6_13;
LKUP STMT vect_sum_7.7_6 = vect__6.6_13
==== ASGN vect_sum_7.7_6 = vect__6.6_13
Optimizing statement vectp_a.4_7 = vectp_a.5_1 + 16;
Replaced 'vectp_a.5_1' with constant '&aD.2604'
LKUP STMT vectp_a.4_7 = &a pointer_plus_expr 16
2>>> STMT vectp_a.4_7 = &a pointer_plus_expr 16
==== ASGN vectp_a.4_7 = &MEM[(void *)&a + 16B]
Optimizing statement ivtmp_8 = 1;
LKUP STMT ivtmp_8 = 1
==== ASGN ivtmp_8 = 1
Optimizing statement vect__6.6_10 = MEM[(int *)vectp_a.4_7];
Replaced 'vectp_a.4_7' with constant '&MEM[(voidD.39 *)&aD.2604 + 16B]'
Folded to: vect__6.6_10 = MEM[(int *)&a + 16B];
LKUP STMT vect__6.6_10 = MEM[(int *)&a + 16B] with .MEM_4
2>>> STMT vect__6.6_10 = MEM[(int *)&a + 16B] with .MEM_4
Optimizing statement vect_sum_7.7_17 = vect_sum_7.7_6 + vect__6.6_10;
Replaced 'vect_sum_7.7_6' with variable 'vect__6.6_13'
gimple_simplified to vect_sum_7.7_17 = vect__6.6_10 + vect__6.6_13;
Folded to: vect_sum_7.7_17 = vect__6.6_10 + vect__6.6_13;
LKUP STMT vect_sum_7.7_17 = vect__6.6_10 plus_expr vect__6.6_13
2>>> STMT vect_sum_7.7_17 = vect__6.6_10 plus_expr vect__6.6_13
...
In x86's case, by this time, the constant vectors have been propagated and
folded into a constant vector:
Optimizing statement vect_cst_.12_23 = { 0, 1, 2, 3 };
LKUP STMT vect_cst_.12_23 = { 0, 1, 2, 3 }
==== ASGN vect_cst_.12_23 = { 0, 1, 2, 3 }
Optimizing statement vect_cst_.11_32 = { 4, 5, 6, 7 };
LKUP STMT vect_cst_.11_32 = { 4, 5, 6, 7 }
==== ASGN vect_cst_.11_32 = { 4, 5, 6, 7 }
Optimizing statement vectp.14_2 = &a[0];
LKUP STMT vectp.14_2 = &a[0]
==== ASGN vectp.14_2 = &a[0]
Optimizing statement MEM[(int *)vectp.14_2] = vect_cst_.12_23;
Replaced 'vectp.14_2' with constant '&aD.1831[0]'
Replaced 'vect_cst_.12_23' with constant '{ 0, 1, 2, 3 }'
Folded to: MEM[(int *)&a] = { 0, 1, 2, 3 };
LKUP STMT MEM[(int *)&a] = { 0, 1, 2, 3 } with .MEM_3(D)
LKUP STMT { 0, 1, 2, 3 } = MEM[(int *)&a] with .MEM_3(D)
LKUP STMT { 0, 1, 2, 3 } = MEM[(int *)&a] with .MEM_25
2>>> STMT { 0, 1, 2, 3 } = MEM[(int *)&a] with .MEM_25
Optimizing statement vectp.14_21 = vectp.14_2 + 16;
Replaced 'vectp.14_2' with constant '&aD.1831[0]'
LKUP STMT vectp.14_21 = &a[0] pointer_plus_expr 16
2>>> STMT vectp.14_21 = &a[0] pointer_plus_expr 16
==== ASGN vectp.14_21 = &MEM[(void *)&a + 16B]
Optimizing statement MEM[(int *)vectp.14_21] = vect_cst_.11_32;
Replaced 'vectp.14_21' with constant '&MEM[(voidD.41 *)&aD.1831 + 16B]'
Replaced 'vect_cst_.11_32' with constant '{ 4, 5, 6, 7 }'
Folded to: MEM[(int *)&a + 16B] = { 4, 5, 6, 7 };
LKUP STMT MEM[(int *)&a + 16B] = { 4, 5, 6, 7 } with .MEM_25
LKUP STMT { 4, 5, 6, 7 } = MEM[(int *)&a + 16B] with .MEM_25
LKUP STMT { 4, 5, 6, 7 } = MEM[(int *)&a + 16B] with .MEM_19
2>>> STMT { 4, 5, 6, 7 } = MEM[(int *)&a + 16B] with .MEM_19
Optimizing statement vectp_a.5_22 = &a;
LKUP STMT vectp_a.5_22 = &a
==== ASGN vectp_a.5_22 = &a
Optimizing statement vect__13.6_20 = MEM[(int *)vectp_a.5_22];
Replaced 'vectp_a.5_22' with constant '&aD.1831'
LKUP STMT vect__13.6_20 = MEM[(int *)&a] with .MEM_19
FIND: { 0, 1, 2, 3 }
Replaced redundant expr '# VUSE <.MEM_19>
MEM[(intD.6 *)&aD.1831]' with '{ 0, 1, 2, 3 }'
==== ASGN vect__13.6_20 = { 0, 1, 2, 3 }
Optimizing statement vect_sum_14.7_13 = vect__13.6_20;
Replaced 'vect__13.6_20' with constant '{ 0, 1, 2, 3 }'
LKUP STMT vect_sum_14.7_13 = { 0, 1, 2, 3 }
==== ASGN vect_sum_14.7_13 = { 0, 1, 2, 3 }
....
While the MEM[vect_ptr + CST] gets replaced correctly by 'a', it doesn't seem
to figure out that the literal pool load 'a = *LC0' is nothing but
vect_cst_.12_23 = { 0, 1, 2, 3 }; and vect_cst_.11_32 = { 4, 5, 6, 7 };
which is the only major difference between how the const vector is initialized
in x86 and aarch64. Is DOM not able to understand 'a = *LC0'?
