execute1: Ease timing on redirect_nia

This eliminates a dependency of r.f.redirect_nia on the carry out
from the main adder in the case of a conditional trap instruction.
We can set r.f.redirect_nia unconditionally, even if no interrupt
is generated.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

execute1.vhdl

@@ -619,12 +619,12 @@ begin
                         end loop;
                     else
                         -- trap instructions (tw, twi, td, tdi)
-                        if or (trapval and insn_to(e_in.insn)) = '1' then
-                            -- generate trap-type program interrupt
-                            exception := '1';
                         v.f.redirect_nia := std_logic_vector(to_unsigned(16#700#, 64));
                         -- set bit 46 to say trap occurred
                         ctrl_tmp.srr1(63 - 46) <= '1';
+                        if or (trapval and insn_to(e_in.insn)) = '1' then
+                            -- generate trap-type program interrupt
+                            exception := '1';
                             report "trap";
                         end if;
                     end if;