On 12/28/2025 7:26 PM, Andrew Pinski wrote:
This fixes up a missed optimization regression for riscv in ifcvt after
r16-6350-g9e61a171244110.
The problem is noce_emit_cmove will fail for QImode. This can show up when
dealing with shifts
and the right hand side is `(subreg:QI (reg:DI) lowpart)`. Trying first for the
subreg mode
fails so the need to try to unwrap the subreg and try for the full mode.
This fixes test_ShiftLeft_eqz in gcc.target/riscv/zicond_ifcvt_opt.c.
Bootstrapped and tested on x86_64-linux-gnu.
PR rtl-optimization/123308
gcc/ChangeLog:
* ifcvt.cc (noce_try_cond_zero_arith): If noce_emit_cmove fails
for a lowpart subreg case, then try the full reg cmove and
take the lowpart subreg afterwards.
OK. It's a different approach than we'd taken internally, but I can't
say the internal approach was any better. Let's try yours and see where
it takes us from a long term maintenance standpoint.
jeff
