https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90372
Bug ID: 90372
Summary: [x64][missed optimization] pushes unused r12 onto
stack on unique_ptr use
Product: gcc
Version: 9.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: marc at kdab dot com
Target Milestone: ---
In the following example: https://godbolt.org/z/jHSYue
one(), using std::unique_ptr, pushes r12 to the stack just to pop it back at
the end. r12 does not appear to be used in-between.
The similar two() function does not do this, even though the rest of the
function (except the stack unwind trampoline) is instruction-by-instruction
identical.
Expected: r12 is not pushed/popped.
