https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118252
Bug ID: 118252
Summary: i386 should implement CASE_VECTOR_SHORTEN_MODE
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: andi-gcc at firstfloor dot org
Target Milestone: ---
Inspired by https://github.com/komrad36/CRC
When generating a jump table for switch gcc always uses .long for PIC or .quad
for non PIC. This both wastes code size and dcache foot print. The offset jump
sequence is slightly longer, but shortening the table makes more than up for
it.
First it should probably always use .long to save dcache, but if the switch
code fits into 16k or 8k it should use .word or .byte. gcc already has an
optimization pass for this as part of jump shortening. But it requires
implementing the
CASE_VECTOR_SHORTEN_MODE target macro which is used by some other targets, but
not x86.
