https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120553
Bug ID: 120553
Summary: Improve code to select between -1 and various values
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: law at gcc dot gnu.org
Target Milestone: ---
I recently added code to improve our ability to generate -1, 1 based on the
sign bit of an input value. ie x < 0 ? -1 : 1.
That can be generalized to generate -1, 2^n for n = 0..63 when the zbs
extension is allowed. Instead of using ori to set the low bit, use bset to set
whatever bit we want like these two example for
long foo1 (long c) { return c >= 0 ? 0x4000 : -1; }
srai a0, a0, 63
bseti a0, a0, 14
