Consolidate trap variants under a single OP_TRAP

This replaces OP_TD, OP_TDI, OP_TW and OP_TWI with a single OP_TRAP,
distinguishing the cases by the input_reg_b and is_32bit fields of
the decode ROM.  This adds the twi and td cases to the decode tables.

For now we make all of the trap instructions unconditionally generate
a trap-type program interrupt if the TO field of the instruction is
all ones, and do nothing otherwise.

This reduces the number of values in insn_type_t from 65 to 62,
meaning that an insn_type_t can now be encoded in 6 bits rather
than 7.

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

decode1.vhdl

@@ -67,8 +67,8 @@ architecture behaviour of decode1 is
 		36 =>       (LDST,   OP_STORE,     RA_OR_ZERO, CONST_SI,    RS,   NONE, '0', '0', '0', '0', ZERO, '0', is4B, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- stw
 		37 =>       (LDST,   OP_STORE,     RA_OR_ZERO, CONST_SI,    RS,   NONE, '0', '0', '0', '0', ZERO, '0', is4B, '0', '0', '1', '0', '0', '0', NONE, '0', '0'), -- stwu
 		 8 =>       (ALU,    OP_ADD,       RA,         CONST_SI,    NONE, RT,   '0', '0', '1', '0', ONE,  '1', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- subfic
-		 2 =>       (ALU,    OP_TDI,       RA,         CONST_SI,    NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- tdi
+		 2 =>       (ALU,    OP_TRAP,      RA,         CONST_SI,    NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- tdi
-		--PPC_TWI 3
+		 3 =>       (ALU,    OP_TRAP,      RA,         CONST_SI,    NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', NONE, '0', '1'), -- twi
 		26 =>       (ALU,    OP_XOR,       NONE,       CONST_UI,    RS,   RA,   '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- xori
 		27 =>       (ALU,    OP_XOR,       NONE,       CONST_UI_HI, RS,   RA,   '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- xoris
 		others   => illegal_inst
@@ -317,8 +317,8 @@ architecture behaviour of decode1 is
 		2#0011001000#  =>       (ALU,    OP_ADD,       RA,         NONE,        NONE, RT,   '0', '0', '1', '0', CA,   '1', NONE, '0', '0', '0', '0', '0', '0', RC,   '0', '0'), -- subfze
 		2#1011001000#  =>       (ALU,    OP_ADD,       RA,         NONE,        NONE, RT,   '0', '0', '1', '0', CA,   '1', NONE, '0', '0', '0', '0', '0', '0', RC,   '0', '0'), -- subfzeo
 		2#1001010110#  =>       (ALU,    OP_NOP,       NONE,       NONE,        NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- sync
-		-- 2#0001000100# td
+		2#0001000100#  =>       (ALU,    OP_TRAP,      RA,         RB,          NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- td
-		2#0000000100#  =>       (ALU,    OP_TW,        RA,         RB,          NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- tw
+		2#0000000100#  =>       (ALU,    OP_TRAP,      RA,         RB,          NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', NONE, '0', '1'), -- tw
 		2#0100111100#  =>       (ALU,    OP_XOR,       NONE,       RB,          RS,   RA,   '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC,   '0', '0'), -- xor
 		others => illegal_inst
 	);

decode_types.vhdl

@@ -16,8 +16,8 @@ package decode_types is
 			 OP_POPCNT, OP_PRTY, OP_RFID,
 			 OP_RLC, OP_RLCL, OP_RLCR, OP_SC, OP_SETB,
 			 OP_SHL, OP_SHR,
-			 OP_SYNC, OP_TD, OP_TDI, OP_TW,
+			 OP_SYNC, OP_TRAP,
-			 OP_TWI, OP_XOR, OP_SIM_CONFIG
+			 OP_XOR, OP_SIM_CONFIG
 			 );
     type input_reg_a_t is (NONE, RA, RA_OR_ZERO, SPR);
     type input_reg_b_t is (NONE, RB, CONST_UI, CONST_SI, CONST_SI_HI, CONST_UI_HI, CONST_LI, CONST_BD, CONST_DS, CONST_M1, CONST_SH, CONST_SH32, SPR);

execute1.vhdl

@@ -726,9 +726,16 @@ begin
 		result := x"0000000000000000";
 		result_en := '1';
 
-	    when OP_TDI =>
+	    when OP_TRAP =>
-		-- Keep our test cases happy for now, ignore trap instructions
+                -- For now, generate a program interrupt if the TO field is all 1s
-		report "OP_TDI FIXME";
+                if insn_to(e_in.insn) = "11111" then
+                    exception := '1';
+                    ctrl_tmp.irq_nia <= std_logic_vector(to_unsigned(16#700#, 64));
+                    ctrl_tmp.srr1 <= msr_copy(ctrl.msr);
+                    -- set bit 46 to say a trap occurred
+                    ctrl_tmp.srr1(63 - 46) <= '1';
+                    report "trap";
+                end if;
 
 	    when OP_ISYNC =>
 		f_out.redirect <= '1';