[Bug target/94687] New: PPC vector fails to optimize shift (used bits)
shawn at git dot icu
gcc-bugzilla@gcc.gnu.org
Tue Apr 21 10:32:28 GMT 2020
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94687
Bug ID: 94687
Summary: PPC vector fails to optimize shift (used bits)
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: shawn at git dot icu
Target Milestone: ---
https://godbolt.org/z/ZyTG9b
#include <altivec.h>
typedef vector unsigned __int128 block;
typedef vector unsigned long long vector2_u64;
block swap_with_shift(block num) {
return num << 64 | num >> 64;
}
block swap_without_shift(block num) {
vector unsigned long long ret;
ret[0] = ((vector2_u64)num)[1];
ret[1] = ((vector2_u64)num)[0];
return (block)ret;
}
typedef unsigned __int128 u128;
u128 swap_scalar(u128 in) {
return in << 64 | in >> 64;
}
swap_with_shift:
xxpermdi 34,34,34,2
addi 9,1,-16
stxvd2x 34,0,9
ld 8,-8(1)
ld 9,-16(1)
mtvsrd 1,8
mtvsrd 0,9
xxpermdi 34,0,1,0
blr
.long 0
.byte 0,0,0,0,0,0,0,0
swap_without_shift:
xxpermdi 34,34,34,2
blr
.long 0
.byte 0,0,0,0,0,0,0,0
swap_scalar:
mr 9,3
mr 3,4
mr 4,9
blr
.long 0
.byte 0,0,0,0,0,0,0,0
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