aco: add p_end_with_regs pseudo instruction

Used by radeonsi shader parts to pass args from one part to another.
It has variable number of operands to reserve fixed registers with
wanted value.

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24442>

src/amd/compiler/aco_insert_exec_mask.cpp

@@ -103,7 +103,8 @@ needs_exact(aco_ptr<Instruction>& instr)
        * epilog without considering the exec mask.
        */
       return instr->isEXP() || instr->opcode == aco_opcode::p_jump_to_epilog ||
-             instr->opcode == aco_opcode::p_dual_src_export_gfx11;
+             instr->opcode == aco_opcode::p_dual_src_export_gfx11 ||
+             instr->opcode == aco_opcode::p_end_with_regs;
    }
 }