https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110748
--- Comment #8 from Vineet Gupta <vineetg at gcc dot gnu.org> ---
(In reply to Jeffrey A. Law from comment #5)
> I'd bet it's const_0_operand not allowing CONST_DOUBLE.
Correct.
> The question is what unintended side effects we'd have if we allowed
> CONST_DOUBLE 0.0 in const_0_operand.
Exactly. I had the same concern.
I do have a hack which creates a new predicate and that seems to do the trick.
+(define_predicate "const_0hf_operand"
+ (and (match_code "const_double")
+ (match_test "op == CONST0_RTX (GET_MODE (op))")))
+
+(define_predicate "reg_or_0_operand_inc_hf"
+ (ior (match_operand 0 "reg_or_0_operand")
+ (match_operand 0 "const_0hf_operand")))
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
- if (!register_operand (dest, mode) && !reg_or_0_operand (src, mode))
+ if (!register_operand (dest, mode) && !reg_or_0_operand_inc_hf (src, mode))
{
And it seems to be generating the desired int 0 for double 0.0.
However to Kito's point, this indeed works in gcc 12 so I first need to bisect
what regressed it in 13.
