Yunus Shaikh 259bb69d65 feat(relinker): move rsp operands that cannot keep their encoding to stubs ...

A leaf whose rsp operand could not keep its encoding after the shift
was skipped: an 8-bit displacement that overflows, an operand at (%rsp)
without a displacement, or an indexed (%rsp,%idx,s) operand. Such an
instruction now moves to a stub, re-encoded with the moved displacement
in 8 bits when it fits and in 32 bits otherwise, followed by a jump
back.

The site covers the instruction and the sequential instructions after
it until it is 5 bytes long. It is refused when a branch lands inside
it, when it would have to cover a branch, ret or rip-relative
instruction (these are not relocated), or when it overlaps the
prologue, an exit, another operand site or an existing stub. Legacy,
REX and VEX forms are re-encoded; EVEX operands, whose 8-bit
displacement is scaled, are still refused. A leaf with no room for a
site is skipped as "rsp operand that cannot move and has no room for a
stub". Operands inside a site that could move in place are carried by
the stub instead, so the site's bytes stay as they were.

The report counts the operand stubs and the operands they carry.

2026-10-23 04:24:32 +00:00

..

codegen

feat(relinker): move rsp operands that cannot keep their encoding to stubs

2026-10-23 04:24:32 +00:00