https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98317
Bug ID: 98317
Summary: Vector Extensions aligned(1) not generating unaligned
loads/stores
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: danielhanchen at gmail dot com
Target Milestone: ---
The ordering of aligned(1) causes GCC to generate movaps / movups.
typedef float float128_tv1 __attribute__ ((aligned(1), vector_size(16)));
typedef float float128_tv2 __attribute__ ((vector_size(16), aligned(1)));
float128_tv1 provides MOVAPS
float128_tv2 provides MOVUPS
It seems like the ordering of the arguments changes the assembly.
https://gcc.godbolt.org/z/5qs7e7
It seems like GCC 10.2 and 9.2 all have this issue.
Unless if this was already documentated, this issue can cause massive issues if
memory is unaligned and an aligned load/store is used instead.
