https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111755
Bug ID: 111755
Summary: The built-in memset function in GCC inadvertently
generates code like "vst1.8 {d8-d9}, [sp:64]", which
assumes an 8-byte alignment on the stack pointer $sp,
leading to alignment violations
Product: gcc
Version: 9.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: kuzume at axell dot co.jp
Target Milestone: ---
The built-in memset function in GCC inadvertently generates code like
"vst1.8 {d8-d9}, [sp:64]"
which assumes an 8-byte alignment on the stack pointer $sp, leading to
alignment violations.
While the issue can be temporarily circumvented using the -fno-builtin-memset
option to inhibit the use of the built-in functions, the stack pointer $sp is
4-byte aligned during C function calls. This might be a bug related to GCC's
built-in function handling.
By the way, the problem can also be resolved by generating assembly listings
without alignment specification, like "vst1.8 {d8-d9}, [sp]". Although, from an
alignment perspective, this is not the optimal performance solution.
