Simple push of empty list.

thun/asm-dump.txt

@@ -5,13 +5,13 @@ label(A),
 mov_imm(0, 0),
 store_word(0, 0, 0),
 mov_imm(0, 4096),
-mov_imm(1, R),
+mov_imm(1, S),
 mov_imm(2, 0),
 mov_imm(3, 0),
 store_word(2, 0, 0),
-label(F),
+label(H),
 sub_imm(1, 1, 0),
-eq_offset(G),
+eq_offset(I),
 load_word(4, 1, 0),
 lsl_imm(5, 4, 2),
 asr_imm(5, 5, 17),
@@ -24,8 +24,7 @@ eq_offset(C),
 add(6, 6, 1),
 label(C),
 load_word(3, 5, 0),
-mov(1,
-6),
+mov(1,6),
 asr_imm(6, 3, 30),
 and_imm(6, 6, 2),
 sub_imm(6, 6, 2),
@@ -36,68 +35,71 @@ and(6, 6, 3),
 do(6),
 label(D),
 sub_imm(0, 0, 4),
+sub_imm(5, 5, 0),
+eq_offset(F),
 sub(2, 5, 0),
 hi_offset(E),
 and_imm(2, 2, 32767),
 label(E),
 lsl_imm(2, 2, 15),
 ior_imm(2, 2, 4),
-label(P),
-store_word(2, 0, 0),
-do_offset(F),
-label(G),
 do_offset(G),
-label(H),
-symbol(H),
+label(F),
+mov_imm(2, 4),
+label(G),
+store_word(2, 0, 0),
+do_offset(H),
+label(I),
+do_offset(I),label(J),
+symbol(J),
 lsl_imm(6, 2, 2),
 asr_imm(6, 6, 17),
-eq_offset(I),
+eq_offset(K),
 add(6, 6, 0),
-label(I),
+label(K),
 lsl_imm(2, 2, 17),
 asr_imm(2, 2, 17),
-eq_offset(J),
+eq_offset(L),
 add(2, 2, 0),
-label(J),
+label(L),
 load_word(7, 2, 0),
 lsl_imm(8, 7, 2),
 asr_imm(8, 8, 17),
-eq_offset(K),
+eq_offset(M),
 add(8, 8, 2),
-label(K),
+label(M),
 lsl_imm(9, 7, 17),
 asr_imm(9, 9, 17),
-eq_offset(L),
+eq_offset(N),
 add(9, 9, 2),
-label(L),
+label(N),
 sub_imm(0, 0, 4),
 sub_imm(8, 8, 0),
-eq_offset(M),
+eq_offset(O),
 sub(8, 8, 0),
 and_imm(8, 8, 32767),
-label(M),
+label(O),
 sub_imm(6, 6, 0),
-eq_offset(N),
+eq_offset(P),
 sub(6, 6, 0),
 and_imm(6, 6, 32767),
-label(N),
+label(P),
 lsl_imm(8, 8, 15),
 ior(8, 8, 6),
 store_word(8, 0, 0),
 sub_imm(0, 0, 4),
 sub_imm(9, 9, 0),
-eq_offset(O),
+eq_offset(Q),
 sub(9, 9, 0),
 and_imm(9, 9, 32767),
-label(O),
+label(Q),
 mov_imm_with_shift(2, 2),
 ior(2, 2, 9),
-do_offset(P),
-label(Q),
-symbol(Q),
-lsl_imm(5, 2,
-2),
+do_offset(G),
+label(R),
+symbol(R),
+lsl_imm(5, 2, 2),
 asr_imm(5, 5, 17),
 do_offset(D),
-label(R),
-expr_cell(Q, 0)].
+label(S),
+expr_cell(R, 0)].

thun/compiler.markII.pl

@@ -62,7 +62,8 @@ Mark II
     % going into push we have the term
     label(PUSH),
     % push2(TOS, TEMP1, SP),  % stack = TERM, stack
-    incr(SP)
+    incr(SP),
+    if_zero(TermAddr, JustPushEmptyList)
 ]),[
     % SP points to the future home of the new stack cell.
     sub(TOS, TermAddr, SP), % TOS := &temp - sp
@@ -74,6 +75,10 @@ Mark II
     % Combine with the offset to the previous stack cell.
     lsl_imm(TOS, TOS, 15),  % TOS := TOS << 15
     ior_imm(TOS, TOS, 4),   % TOS := TOS | 4
+    do_offset(Done),
+    label(JustPushEmptyList),
+    mov_imm(TOS, 4),  % TOS is a pair record with 0 as the head addr
+    % and the previous word in RAM as tail addr.
 
     label(Done),
     store_word(TOS, SP, 0),   % RAM[SP] := TOS