Add test opt4 for block reg propagation

This tests the values of one basic block is propagated to another one.

Author: boriel

tests/functional/opt4_block_regs.asm

@@ -0,0 +1,46 @@
+	org 32768
+__START_PROGRAM:
+	di
+	push ix
+	push iy
+	exx
+	push hl
+	exx
+	ld hl, 0
+	add hl, sp
+	ld (__CALL_BACK__), hl
+	ei
+	ld hl, (_x)
+	ld de, 25
+	add hl, de
+	ld a, 50
+	cp (hl)
+	jp nc, __LABEL1
+	ld hl, (_x)
+	add hl, de
+	xor a
+	ld (hl), a
+__LABEL1:
+	ld bc, 0
+__END_PROGRAM:
+	di
+	ld hl, (__CALL_BACK__)
+	ld sp, hl
+	exx
+	pop hl
+	pop iy
+	pop ix
+	exx
+	ei
+	ret
+__CALL_BACK__:
+	DEFW 0
+
+ZXBASIC_USER_DATA:
+_x:
+	DEFB 00, 00
+	; Defines DATA END --> HEAP size is 0
+ZXBASIC_USER_DATA_END EQU ZXBASIC_MEM_HEAP
+	; Defines USER DATA Length in bytes
+ZXBASIC_USER_DATA_LEN EQU ZXBASIC_USER_DATA_END - ZXBASIC_USER_DATA
+	END

tests/functional/opt4_block_regs.bas

@@ -0,0 +1,12 @@
+REM checks for register propagation
+REM the cpu state of the preceding basic block(s)
+REM can be propagated to the current one for deeper
+REM optimizations
+
+DIM x As Uinteger
+#define spriteTimer (x + 25)
+
+if peek(spriteTimer)>50 then
+    poke spriteTimer,0
+end if
+